Add unmodified Teensy files

BUILD file and modifications to sanify coming soon. These are unmodified
from Teensyduino 1.37 for change tracking purposes.

Change-Id: Id55e2eba0e03260d14ea58ae4c536ae271315164
diff --git a/motors/usb/usb_desc.c b/motors/usb/usb_desc.c
new file mode 100644
index 0000000..efb50a8
--- /dev/null
+++ b/motors/usb/usb_desc.c
@@ -0,0 +1,1488 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#if F_CPU >= 20000000
+
+#define USB_DESC_LIST_DEFINE
+#include "usb_desc.h"
+#ifdef NUM_ENDPOINTS
+#include "usb_names.h"
+#include "kinetis.h"
+#include "avr_functions.h"
+
+// USB Descriptors are binary data which the USB host reads to
+// automatically detect a USB device's capabilities.  The format
+// and meaning of every field is documented in numerous USB
+// standards.  When working with USB descriptors, despite the
+// complexity of the standards and poor writing quality in many
+// of those documents, remember descriptors are nothing more
+// than constant binary data that tells the USB host what the
+// device can do.  Computers will load drivers based on this data.
+// Those drivers then communicate on the endpoints specified by
+// the descriptors.
+
+// To configure a new combination of interfaces or make minor
+// changes to existing configuration (eg, change the name or ID
+// numbers), usually you would edit "usb_desc.h".  This file
+// is meant to be configured by the header, so generally it is
+// only edited to add completely new USB interfaces or features.
+
+
+
+// **************************************************************
+//   USB Device
+// **************************************************************
+
+#define LSB(n) ((n) & 255)
+#define MSB(n) (((n) >> 8) & 255)
+
+// USB Device Descriptor.  The USB host reads this first, to learn
+// what type of device is connected.
+static uint8_t device_descriptor[] = {
+        18,                                     // bLength
+        1,                                      // bDescriptorType
+        0x01, 0x01,                             // bcdUSB
+#ifdef DEVICE_CLASS
+        DEVICE_CLASS,                           // bDeviceClass
+#else
+	0,
+#endif
+#ifdef DEVICE_SUBCLASS
+        DEVICE_SUBCLASS,                        // bDeviceSubClass
+#else
+	0,
+#endif
+#ifdef DEVICE_PROTOCOL
+        DEVICE_PROTOCOL,                        // bDeviceProtocol
+#else
+	0,
+#endif
+        EP0_SIZE,                               // bMaxPacketSize0
+        LSB(VENDOR_ID), MSB(VENDOR_ID),         // idVendor
+        LSB(PRODUCT_ID), MSB(PRODUCT_ID),       // idProduct
+        0x00, 0x02,                             // bcdDevice
+        1,                                      // iManufacturer
+        2,                                      // iProduct
+        3,                                      // iSerialNumber
+        1                                       // bNumConfigurations
+};
+
+// These descriptors must NOT be "const", because the USB DMA
+// has trouble accessing flash memory with enough bandwidth
+// while the processor is executing from flash.
+
+
+
+// **************************************************************
+//   HID Report Descriptors
+// **************************************************************
+
+// Each HID interface needs a special report descriptor that tells
+// the meaning and format of the data.
+
+#ifdef KEYBOARD_INTERFACE
+// Keyboard Protocol 1, HID 1.11 spec, Appendix B, page 59-60
+static uint8_t keyboard_report_desc[] = {
+        0x05, 0x01,                     // Usage Page (Generic Desktop),
+        0x09, 0x06,                     // Usage (Keyboard),
+        0xA1, 0x01,                     // Collection (Application),
+        0x75, 0x01,                     //   Report Size (1),
+        0x95, 0x08,                     //   Report Count (8),
+        0x05, 0x07,                     //   Usage Page (Key Codes),
+        0x19, 0xE0,                     //   Usage Minimum (224),
+        0x29, 0xE7,                     //   Usage Maximum (231),
+        0x15, 0x00,                     //   Logical Minimum (0),
+        0x25, 0x01,                     //   Logical Maximum (1),
+        0x81, 0x02,                     //   Input (Data, Variable, Absolute), ;Modifier keys
+        0x95, 0x01,                     //   Report Count (1),
+        0x75, 0x08,                     //   Report Size (8),
+        0x81, 0x03,                     //   Input (Constant),          ;Reserved byte
+        0x95, 0x05,                     //   Report Count (5),
+        0x75, 0x01,                     //   Report Size (1),
+        0x05, 0x08,                     //   Usage Page (LEDs),
+        0x19, 0x01,                     //   Usage Minimum (1),
+        0x29, 0x05,                     //   Usage Maximum (5),
+        0x91, 0x02,                     //   Output (Data, Variable, Absolute), ;LED report
+        0x95, 0x01,                     //   Report Count (1),
+        0x75, 0x03,                     //   Report Size (3),
+        0x91, 0x03,                     //   Output (Constant),         ;LED report padding
+        0x95, 0x06,                     //   Report Count (6),
+        0x75, 0x08,                     //   Report Size (8),
+        0x15, 0x00,                     //   Logical Minimum (0),
+        0x25, 0x7F,                     //   Logical Maximum(104),
+        0x05, 0x07,                     //   Usage Page (Key Codes),
+        0x19, 0x00,                     //   Usage Minimum (0),
+        0x29, 0x7F,                     //   Usage Maximum (104),
+        0x81, 0x00,                     //   Input (Data, Array),       ;Normal keys
+        0xC0                            // End Collection
+};
+#endif
+
+#ifdef KEYMEDIA_INTERFACE
+static uint8_t keymedia_report_desc[] = {
+        0x05, 0x0C,                     // Usage Page (Consumer)
+        0x09, 0x01,                     // Usage (Consumer Controls)
+        0xA1, 0x01,                     // Collection (Application)
+        0x75, 0x0A,                     //   Report Size (10)
+        0x95, 0x04,                     //   Report Count (4)
+        0x19, 0x00,                     //   Usage Minimum (0)
+        0x2A, 0x9C, 0x02,               //   Usage Maximum (0x29C)
+        0x15, 0x00,                     //   Logical Minimum (0)
+        0x26, 0x9C, 0x02,               //   Logical Maximum (0x29C)
+        0x81, 0x00,                     //   Input (Data, Array)
+        0x05, 0x01,                     //   Usage Page (Generic Desktop)
+        0x75, 0x08,                     //   Report Size (8)
+        0x95, 0x03,                     //   Report Count (3)
+        0x19, 0x00,                     //   Usage Minimum (0)
+        0x29, 0xB7,                     //   Usage Maximum (0xB7)
+        0x15, 0x00,                     //   Logical Minimum (0)
+        0x26, 0xB7, 0x00,               //   Logical Maximum (0xB7)
+        0x81, 0x00,                     //   Input (Data, Array)
+        0xC0                            // End Collection
+};
+#endif
+
+#ifdef MOUSE_INTERFACE
+// Mouse Protocol 1, HID 1.11 spec, Appendix B, page 59-60, with wheel extension
+static uint8_t mouse_report_desc[] = {
+        0x05, 0x01,                     // Usage Page (Generic Desktop)
+        0x09, 0x02,                     // Usage (Mouse)
+        0xA1, 0x01,                     // Collection (Application)
+        0x85, 0x01,                     //   REPORT_ID (1)
+        0x05, 0x09,                     //   Usage Page (Button)
+        0x19, 0x01,                     //   Usage Minimum (Button #1)
+        0x29, 0x08,                     //   Usage Maximum (Button #8)
+        0x15, 0x00,                     //   Logical Minimum (0)
+        0x25, 0x01,                     //   Logical Maximum (1)
+        0x95, 0x08,                     //   Report Count (8)
+        0x75, 0x01,                     //   Report Size (1)
+        0x81, 0x02,                     //   Input (Data, Variable, Absolute)
+        0x05, 0x01,                     //   Usage Page (Generic Desktop)
+        0x09, 0x30,                     //   Usage (X)
+        0x09, 0x31,                     //   Usage (Y)
+        0x09, 0x38,                     //   Usage (Wheel)
+        0x15, 0x81,                     //   Logical Minimum (-127)
+        0x25, 0x7F,                     //   Logical Maximum (127)
+        0x75, 0x08,                     //   Report Size (8),
+        0x95, 0x03,                     //   Report Count (3),
+        0x81, 0x06,                     //   Input (Data, Variable, Relative)
+        0x05, 0x0C,                     //   Usage Page (Consumer)
+        0x0A, 0x38, 0x02,               //   Usage (AC Pan)
+        0x15, 0x81,                     //   Logical Minimum (-127)
+        0x25, 0x7F,                     //   Logical Maximum (127)
+        0x75, 0x08,                     //   Report Size (8),
+        0x95, 0x01,                     //   Report Count (1),
+        0x81, 0x06,                     //   Input (Data, Variable, Relative)
+        0xC0,                           // End Collection
+        0x05, 0x01,                     // Usage Page (Generic Desktop)
+        0x09, 0x02,                     // Usage (Mouse)
+        0xA1, 0x01,                     // Collection (Application)
+        0x85, 0x02,                     //   REPORT_ID (2)
+        0x05, 0x01,                     //   Usage Page (Generic Desktop)
+        0x09, 0x30,                     //   Usage (X)
+        0x09, 0x31,                     //   Usage (Y)
+        0x15, 0x00,                     //   Logical Minimum (0)
+        0x26, 0xFF, 0x7F,               //   Logical Maximum (32767)
+        0x75, 0x10,                     //   Report Size (16),
+        0x95, 0x02,                     //   Report Count (2),
+        0x81, 0x02,                     //   Input (Data, Variable, Absolute)
+        0xC0                            // End Collection
+};
+#endif
+
+#ifdef JOYSTICK_INTERFACE
+#if JOYSTICK_SIZE == 12
+static uint8_t joystick_report_desc[] = {
+        0x05, 0x01,                     // Usage Page (Generic Desktop)
+        0x09, 0x04,                     // Usage (Joystick)
+        0xA1, 0x01,                     // Collection (Application)
+        0x15, 0x00,                     //   Logical Minimum (0)
+        0x25, 0x01,                     //   Logical Maximum (1)
+        0x75, 0x01,                     //   Report Size (1)
+        0x95, 0x20,                     //   Report Count (32)
+        0x05, 0x09,                     //   Usage Page (Button)
+        0x19, 0x01,                     //   Usage Minimum (Button #1)
+        0x29, 0x20,                     //   Usage Maximum (Button #32)
+        0x81, 0x02,                     //   Input (variable,absolute)
+        0x15, 0x00,                     //   Logical Minimum (0)
+        0x25, 0x07,                     //   Logical Maximum (7)
+        0x35, 0x00,                     //   Physical Minimum (0)
+        0x46, 0x3B, 0x01,               //   Physical Maximum (315)
+        0x75, 0x04,                     //   Report Size (4)
+        0x95, 0x01,                     //   Report Count (1)
+        0x65, 0x14,                     //   Unit (20)
+        0x05, 0x01,                     //   Usage Page (Generic Desktop)
+        0x09, 0x39,                     //   Usage (Hat switch)
+        0x81, 0x42,                     //   Input (variable,absolute,null_state)
+        0x05, 0x01,                     //   Usage Page (Generic Desktop)
+        0x09, 0x01,                     //   Usage (Pointer)
+        0xA1, 0x00,                     //   Collection ()
+        0x15, 0x00,                     //     Logical Minimum (0)
+        0x26, 0xFF, 0x03,               //     Logical Maximum (1023)
+        0x75, 0x0A,                     //     Report Size (10)
+        0x95, 0x04,                     //     Report Count (4)
+        0x09, 0x30,                     //     Usage (X)
+        0x09, 0x31,                     //     Usage (Y)
+        0x09, 0x32,                     //     Usage (Z)
+        0x09, 0x35,                     //     Usage (Rz)
+        0x81, 0x02,                     //     Input (variable,absolute)
+        0xC0,                           //   End Collection
+        0x15, 0x00,                     //   Logical Minimum (0)
+        0x26, 0xFF, 0x03,               //   Logical Maximum (1023)
+        0x75, 0x0A,                     //   Report Size (10)
+        0x95, 0x02,                     //   Report Count (2)
+        0x09, 0x36,                     //   Usage (Slider)
+        0x09, 0x36,                     //   Usage (Slider)
+        0x81, 0x02,                     //   Input (variable,absolute)
+        0xC0                            // End Collection
+};
+#elif JOYSTICK_SIZE == 64
+// extreme joystick  (to use this, edit JOYSTICK_SIZE to 64 in usb_desc.h)
+//  128 buttons   16
+//    6 axes      12
+//   17 sliders   34
+//    4 pov        2
+static uint8_t joystick_report_desc[] = {
+        0x05, 0x01,                     // Usage Page (Generic Desktop)
+        0x09, 0x04,                     // Usage (Joystick)
+        0xA1, 0x01,                     // Collection (Application)
+        0x15, 0x00,                     // Logical Minimum (0)
+        0x25, 0x01,                     // Logical Maximum (1)
+        0x75, 0x01,                     // Report Size (1)
+        0x95, 0x80,                     // Report Count (128)
+        0x05, 0x09,                     // Usage Page (Button)
+        0x19, 0x01,                     // Usage Minimum (Button #1)
+        0x29, 0x80,                     // Usage Maximum (Button #128)
+        0x81, 0x02,                     // Input (variable,absolute)
+        0x05, 0x01,                     // Usage Page (Generic Desktop)
+        0x09, 0x01,                     // Usage (Pointer)
+        0xA1, 0x00,                     // Collection ()
+        0x15, 0x00,                     // Logical Minimum (0)
+        0x27, 0xFF, 0xFF, 0, 0,         // Logical Maximum (65535)
+        0x75, 0x10,                     // Report Size (16)
+        0x95, 23,                       // Report Count (23)
+        0x09, 0x30,                     // Usage (X)
+        0x09, 0x31,                     // Usage (Y)
+        0x09, 0x32,                     // Usage (Z)
+        0x09, 0x33,                     // Usage (Rx)
+        0x09, 0x34,                     // Usage (Ry)
+        0x09, 0x35,                     // Usage (Rz)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x09, 0x36,                     // Usage (Slider)
+        0x81, 0x02,                     // Input (variable,absolute)
+        0xC0,                           // End Collection
+        0x15, 0x00,                     // Logical Minimum (0)
+        0x25, 0x07,                     // Logical Maximum (7)
+        0x35, 0x00,                     // Physical Minimum (0)
+        0x46, 0x3B, 0x01,               // Physical Maximum (315)
+        0x75, 0x04,                     // Report Size (4)
+        0x95, 0x04,                     // Report Count (4)
+        0x65, 0x14,                     // Unit (20)
+        0x05, 0x01,                     // Usage Page (Generic Desktop)
+        0x09, 0x39,                     // Usage (Hat switch)
+        0x09, 0x39,                     // Usage (Hat switch)
+        0x09, 0x39,                     // Usage (Hat switch)
+        0x09, 0x39,                     // Usage (Hat switch)
+        0x81, 0x42,                     // Input (variable,absolute,null_state)
+        0xC0                            // End Collection
+};
+#endif // JOYSTICK_SIZE
+#endif // JOYSTICK_INTERFACE
+
+#ifdef MULTITOUCH_INTERFACE
+// https://forum.pjrc.com/threads/32331-USB-HID-Touchscreen-support-needed
+// https://msdn.microsoft.com/en-us/library/windows/hardware/jj151563%28v=vs.85%29.aspx
+// https://msdn.microsoft.com/en-us/library/windows/hardware/jj151565%28v=vs.85%29.aspx
+// https://msdn.microsoft.com/en-us/library/windows/hardware/ff553734%28v=vs.85%29.aspx
+// https://msdn.microsoft.com/en-us/library/windows/hardware/jj151564%28v=vs.85%29.aspx
+// download.microsoft.com/download/a/d/f/adf1347d-08dc-41a4-9084-623b1194d4b2/digitizerdrvs_touch.docx
+static uint8_t multitouch_report_desc[] = {
+        0x05, 0x0D,                     // Usage Page (Digitizer)
+        0x09, 0x04,                     // Usage (Touch Screen)
+        0xa1, 0x01,                     // Collection (Application)
+        0x09, 0x22,                     //   Usage (Finger)
+        0xA1, 0x02,                     //   Collection (Logical)
+        0x09, 0x42,                     //     Usage (Tip Switch)
+        0x15, 0x00,                     //     Logical Minimum (0)
+        0x25, 0x01,                     //     Logical Maximum (1)
+        0x75, 0x01,                     //     Report Size (1)
+        0x95, 0x01,                     //     Report Count (1)
+        0x81, 0x02,                     //     Input (variable,absolute)
+        0x09, 0x30,                     //     Usage (Pressure)
+        0x25, 0x7F,                     //     Logical Maximum (127)
+        0x75, 0x07,                     //     Report Size (7)
+        0x95, 0x01,                     //     Report Count (1)
+        0x81, 0x02,                     //     Input (variable,absolute)
+        0x09, 0x51,                     //     Usage (Contact Identifier)
+        0x26, 0xFF, 0x00,               //     Logical Maximum (255)
+        0x75, 0x08,                     //     Report Size (8)
+        0x95, 0x01,                     //     Report Count (1)
+        0x81, 0x02,                     //     Input (variable,absolute)
+        0x05, 0x01,                     //     Usage Page (Generic Desktop)
+        0x09, 0x30,                     //     Usage (X)
+        0x09, 0x31,                     //     Usage (Y)
+        0x26, 0xFF, 0x7F,               //     Logical Maximum (32767)
+        0x65, 0x00,                     //     Unit (None)  <-- probably needs real units?
+        0x75, 0x10,                     //     Report Size (16)
+        0x95, 0x02,                     //     Report Count (2)
+        0x81, 0x02,                     //     Input (variable,absolute)
+        0xC0,                           //   End Collection
+        0x05, 0x0D,                     //   Usage Page (Digitizer)
+        0x27, 0xFF, 0xFF, 0, 0,         //   Logical Maximum (65535)
+        0x75, 0x10,                     //   Report Size (16)
+        0x95, 0x01,                     //   Report Count (1)
+        0x09, 0x56,                     //   Usage (Scan Time)
+        0x81, 0x02,                     //   Input (variable,absolute)
+        0x09, 0x54,                     //   Usage (Contact Count)
+        0x25, MULTITOUCH_FINGERS,       //   Logical Maximum (10)
+        0x75, 0x08,                     //   Report Size (8)
+        0x95, 0x01,                     //   Report Count (1)
+        0x81, 0x02,                     //   Input (variable,absolute)
+        0x05, 0x0D,                     //   Usage Page (Digitizers)
+        0x09, 0x55,                     //   Usage (Contact Count Maximum)
+        0x25, MULTITOUCH_FINGERS,       //   Logical Maximum (10)
+        0x75, 0x08,                     //   Report Size (8)
+        0x95, 0x01,                     //   Report Count (1)
+        0xB1, 0x02,                     //   Feature (variable,absolute)
+        0xC0                            // End Collection
+};
+#endif
+
+#ifdef SEREMU_INTERFACE
+static uint8_t seremu_report_desc[] = {
+        0x06, 0xC9, 0xFF,               // Usage Page 0xFFC9 (vendor defined)
+        0x09, 0x04,                     // Usage 0x04
+        0xA1, 0x5C,                     // Collection 0x5C
+        0x75, 0x08,                     //   report size = 8 bits (global)
+        0x15, 0x00,                     //   logical minimum = 0 (global)
+        0x26, 0xFF, 0x00,               //   logical maximum = 255 (global)
+        0x95, SEREMU_TX_SIZE,           //   report count (global)
+        0x09, 0x75,                     //   usage (local)
+        0x81, 0x02,                     //   Input
+        0x95, SEREMU_RX_SIZE,           //   report count (global)
+        0x09, 0x76,                     //   usage (local)
+        0x91, 0x02,                     //   Output
+        0x95, 0x04,                     //   report count (global)
+        0x09, 0x76,                     //   usage (local)
+        0xB1, 0x02,                     //   Feature
+        0xC0                            // end collection
+};
+#endif
+
+#ifdef RAWHID_INTERFACE
+static uint8_t rawhid_report_desc[] = {
+        0x06, LSB(RAWHID_USAGE_PAGE), MSB(RAWHID_USAGE_PAGE),
+        0x0A, LSB(RAWHID_USAGE), MSB(RAWHID_USAGE),
+        0xA1, 0x01,                     // Collection 0x01
+        0x75, 0x08,                     //   report size = 8 bits
+        0x15, 0x00,                     //   logical minimum = 0
+        0x26, 0xFF, 0x00,               //   logical maximum = 255
+        0x95, RAWHID_TX_SIZE,           //   report count
+        0x09, 0x01,                     //   usage
+        0x81, 0x02,                     //   Input (array)
+        0x95, RAWHID_RX_SIZE,           //   report count
+        0x09, 0x02,                     //   usage
+        0x91, 0x02,                     //   Output (array)
+        0xC0                            // end collection
+};
+#endif
+
+#ifdef FLIGHTSIM_INTERFACE
+static uint8_t flightsim_report_desc[] = {
+        0x06, 0x1C, 0xFF,               // Usage page = 0xFF1C
+        0x0A, 0x39, 0xA7,               // Usage = 0xA739
+        0xA1, 0x01,                     // Collection 0x01
+        0x75, 0x08,                     //   report size = 8 bits
+        0x15, 0x00,                     //   logical minimum = 0
+        0x26, 0xFF, 0x00,               //   logical maximum = 255
+        0x95, FLIGHTSIM_TX_SIZE,        //   report count
+        0x09, 0x01,                     //   usage
+        0x81, 0x02,                     //   Input (array)
+        0x95, FLIGHTSIM_RX_SIZE,        //   report count
+        0x09, 0x02,                     //   usage
+        0x91, 0x02,                     //   Output (array)
+        0xC0                            // end collection
+};
+#endif
+
+
+// **************************************************************
+//   USB Descriptor Sizes
+// **************************************************************
+
+// pre-compute the size and position of everything in the config descriptor
+//
+#define CONFIG_HEADER_DESCRIPTOR_SIZE	9
+
+#define CDC_IAD_DESCRIPTOR_POS		CONFIG_HEADER_DESCRIPTOR_SIZE
+#ifdef  CDC_IAD_DESCRIPTOR
+#define CDC_IAD_DESCRIPTOR_SIZE		8
+#else
+#define CDC_IAD_DESCRIPTOR_SIZE		0
+#endif
+
+#define CDC_DATA_INTERFACE_DESC_POS	CDC_IAD_DESCRIPTOR_POS+CDC_IAD_DESCRIPTOR_SIZE
+#ifdef  CDC_DATA_INTERFACE
+#define CDC_DATA_INTERFACE_DESC_SIZE	9+5+5+4+5+7+9+7+7
+#else
+#define CDC_DATA_INTERFACE_DESC_SIZE	0
+#endif
+
+#define MIDI_INTERFACE_DESC_POS		CDC_DATA_INTERFACE_DESC_POS+CDC_DATA_INTERFACE_DESC_SIZE
+#ifdef  MIDI_INTERFACE
+#define MIDI_INTERFACE_DESC_SIZE	9+7+6+6+9+9+9+5+9+5
+#else
+#define MIDI_INTERFACE_DESC_SIZE	0
+#endif
+
+#define KEYBOARD_INTERFACE_DESC_POS	MIDI_INTERFACE_DESC_POS+MIDI_INTERFACE_DESC_SIZE
+#ifdef  KEYBOARD_INTERFACE
+#define KEYBOARD_INTERFACE_DESC_SIZE	9+9+7
+#define KEYBOARD_HID_DESC_OFFSET	KEYBOARD_INTERFACE_DESC_POS+9
+#else
+#define KEYBOARD_INTERFACE_DESC_SIZE	0
+#endif
+
+#define MOUSE_INTERFACE_DESC_POS	KEYBOARD_INTERFACE_DESC_POS+KEYBOARD_INTERFACE_DESC_SIZE
+#ifdef  MOUSE_INTERFACE
+#define MOUSE_INTERFACE_DESC_SIZE	9+9+7
+#define MOUSE_HID_DESC_OFFSET		MOUSE_INTERFACE_DESC_POS+9
+#else
+#define MOUSE_INTERFACE_DESC_SIZE	0
+#endif
+
+#define RAWHID_INTERFACE_DESC_POS	MOUSE_INTERFACE_DESC_POS+MOUSE_INTERFACE_DESC_SIZE
+#ifdef  RAWHID_INTERFACE
+#define RAWHID_INTERFACE_DESC_SIZE	9+9+7+7
+#define RAWHID_HID_DESC_OFFSET		RAWHID_INTERFACE_DESC_POS+9
+#else
+#define RAWHID_INTERFACE_DESC_SIZE	0
+#endif
+
+#define FLIGHTSIM_INTERFACE_DESC_POS	RAWHID_INTERFACE_DESC_POS+RAWHID_INTERFACE_DESC_SIZE
+#ifdef  FLIGHTSIM_INTERFACE
+#define FLIGHTSIM_INTERFACE_DESC_SIZE	9+9+7+7
+#define FLIGHTSIM_HID_DESC_OFFSET	FLIGHTSIM_INTERFACE_DESC_POS+9
+#else
+#define FLIGHTSIM_INTERFACE_DESC_SIZE	0
+#endif
+
+#define SEREMU_INTERFACE_DESC_POS	FLIGHTSIM_INTERFACE_DESC_POS+FLIGHTSIM_INTERFACE_DESC_SIZE
+#ifdef  SEREMU_INTERFACE
+#define SEREMU_INTERFACE_DESC_SIZE	9+9+7+7
+#define SEREMU_HID_DESC_OFFSET		SEREMU_INTERFACE_DESC_POS+9
+#else
+#define SEREMU_INTERFACE_DESC_SIZE	0
+#endif
+
+#define JOYSTICK_INTERFACE_DESC_POS	SEREMU_INTERFACE_DESC_POS+SEREMU_INTERFACE_DESC_SIZE
+#ifdef  JOYSTICK_INTERFACE
+#define JOYSTICK_INTERFACE_DESC_SIZE	9+9+7
+#define JOYSTICK_HID_DESC_OFFSET	JOYSTICK_INTERFACE_DESC_POS+9
+#else
+#define JOYSTICK_INTERFACE_DESC_SIZE	0
+#endif
+
+#define MTP_INTERFACE_DESC_POS		JOYSTICK_INTERFACE_DESC_POS+JOYSTICK_INTERFACE_DESC_SIZE
+#ifdef  MTP_INTERFACE
+#define MTP_INTERFACE_DESC_SIZE		9+7+7+7
+#else
+#define MTP_INTERFACE_DESC_SIZE	0
+#endif
+
+#define KEYMEDIA_INTERFACE_DESC_POS	MTP_INTERFACE_DESC_POS+MTP_INTERFACE_DESC_SIZE
+#ifdef  KEYMEDIA_INTERFACE
+#define KEYMEDIA_INTERFACE_DESC_SIZE	9+9+7
+#define KEYMEDIA_HID_DESC_OFFSET	KEYMEDIA_INTERFACE_DESC_POS+9
+#else
+#define KEYMEDIA_INTERFACE_DESC_SIZE	0
+#endif
+
+#define AUDIO_INTERFACE_DESC_POS	KEYMEDIA_INTERFACE_DESC_POS+KEYMEDIA_INTERFACE_DESC_SIZE
+#ifdef  AUDIO_INTERFACE
+#define AUDIO_INTERFACE_DESC_SIZE	8 + 9+10+12+9+12+10+9 + 9+9+7+11+9+7 + 9+9+7+11+9+7+9
+#else
+#define AUDIO_INTERFACE_DESC_SIZE	0
+#endif
+
+#define MULTITOUCH_INTERFACE_DESC_POS	AUDIO_INTERFACE_DESC_POS+AUDIO_INTERFACE_DESC_SIZE
+#ifdef  MULTITOUCH_INTERFACE
+#define MULTITOUCH_INTERFACE_DESC_SIZE	9+9+7
+#define MULTITOUCH_HID_DESC_OFFSET	MULTITOUCH_INTERFACE_DESC_POS+9
+#else
+#define MULTITOUCH_INTERFACE_DESC_SIZE	0
+#endif
+
+#define CONFIG_DESC_SIZE		MULTITOUCH_INTERFACE_DESC_POS+MULTITOUCH_INTERFACE_DESC_SIZE
+
+
+
+// **************************************************************
+//   USB Configuration
+// **************************************************************
+
+// USB Configuration Descriptor.  This huge descriptor tells all
+// of the devices capbilities.
+static uint8_t config_descriptor[CONFIG_DESC_SIZE] = {
+        // configuration descriptor, USB spec 9.6.3, page 264-266, Table 9-10
+        9,                                      // bLength;
+        2,                                      // bDescriptorType;
+        LSB(CONFIG_DESC_SIZE),                 // wTotalLength
+        MSB(CONFIG_DESC_SIZE),
+        NUM_INTERFACE,                          // bNumInterfaces
+        1,                                      // bConfigurationValue
+        0,                                      // iConfiguration
+        0xC0,                                   // bmAttributes
+        50,                                     // bMaxPower
+
+#ifdef CDC_IAD_DESCRIPTOR
+        // interface association descriptor, USB ECN, Table 9-Z
+        8,                                      // bLength
+        11,                                     // bDescriptorType
+        CDC_STATUS_INTERFACE,                   // bFirstInterface
+        2,                                      // bInterfaceCount
+        0x02,                                   // bFunctionClass
+        0x02,                                   // bFunctionSubClass
+        0x01,                                   // bFunctionProtocol
+        4,                                      // iFunction
+#endif
+
+#ifdef CDC_DATA_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        CDC_STATUS_INTERFACE,			// bInterfaceNumber
+        0,                                      // bAlternateSetting
+        1,                                      // bNumEndpoints
+        0x02,                                   // bInterfaceClass
+        0x02,                                   // bInterfaceSubClass
+        0x01,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // CDC Header Functional Descriptor, CDC Spec 5.2.3.1, Table 26
+        5,                                      // bFunctionLength
+        0x24,                                   // bDescriptorType
+        0x00,                                   // bDescriptorSubtype
+        0x10, 0x01,                             // bcdCDC
+        // Call Management Functional Descriptor, CDC Spec 5.2.3.2, Table 27
+        5,                                      // bFunctionLength
+        0x24,                                   // bDescriptorType
+        0x01,                                   // bDescriptorSubtype
+        0x01,                                   // bmCapabilities
+        1,                                      // bDataInterface
+        // Abstract Control Management Functional Descriptor, CDC Spec 5.2.3.3, Table 28
+        4,                                      // bFunctionLength
+        0x24,                                   // bDescriptorType
+        0x02,                                   // bDescriptorSubtype
+        0x06,                                   // bmCapabilities
+        // Union Functional Descriptor, CDC Spec 5.2.3.8, Table 33
+        5,                                      // bFunctionLength
+        0x24,                                   // bDescriptorType
+        0x06,                                   // bDescriptorSubtype
+        CDC_STATUS_INTERFACE,                   // bMasterInterface
+        CDC_DATA_INTERFACE,                     // bSlaveInterface0
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        CDC_ACM_ENDPOINT | 0x80,                // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        CDC_ACM_SIZE, 0,                        // wMaxPacketSize
+        64,                                     // bInterval
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        CDC_DATA_INTERFACE,                     // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        2,                                      // bNumEndpoints
+        0x0A,                                   // bInterfaceClass
+        0x00,                                   // bInterfaceSubClass
+        0x00,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        CDC_RX_ENDPOINT,                        // bEndpointAddress
+        0x02,                                   // bmAttributes (0x02=bulk)
+        CDC_RX_SIZE, 0,                         // wMaxPacketSize
+        0,                                      // bInterval
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        CDC_TX_ENDPOINT | 0x80,                 // bEndpointAddress
+        0x02,                                   // bmAttributes (0x02=bulk)
+        CDC_TX_SIZE, 0,                         // wMaxPacketSize
+        0,                                      // bInterval
+#endif // CDC_DATA_INTERFACE
+
+#ifdef MIDI_INTERFACE
+        // Standard MS Interface Descriptor,
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        MIDI_INTERFACE,                         // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        2,                                      // bNumEndpoints
+        0x01,                                   // bInterfaceClass (0x01 = Audio)
+        0x03,                                   // bInterfaceSubClass (0x03 = MIDI)
+        0x00,                                   // bInterfaceProtocol (unused for MIDI)
+        0,                                      // iInterface
+        // MIDI MS Interface Header, USB MIDI 6.1.2.1, page 21, Table 6-2
+        7,                                      // bLength
+        0x24,                                   // bDescriptorType = CS_INTERFACE
+        0x01,                                   // bDescriptorSubtype = MS_HEADER
+        0x00, 0x01,                             // bcdMSC = revision 01.00
+        0x41, 0x00,                             // wTotalLength
+        // MIDI IN Jack Descriptor, B.4.3, Table B-7 (embedded), page 40
+        6,                                      // bLength
+        0x24,                                   // bDescriptorType = CS_INTERFACE
+        0x02,                                   // bDescriptorSubtype = MIDI_IN_JACK
+        0x01,                                   // bJackType = EMBEDDED
+        1,                                      // bJackID, ID = 1
+        0,                                      // iJack
+        // MIDI IN Jack Descriptor, B.4.3, Table B-8 (external), page 40
+        6,                                      // bLength
+        0x24,                                   // bDescriptorType = CS_INTERFACE
+        0x02,                                   // bDescriptorSubtype = MIDI_IN_JACK
+        0x02,                                   // bJackType = EXTERNAL
+        2,                                      // bJackID, ID = 2
+        0,                                      // iJack
+        // MIDI OUT Jack Descriptor, B.4.4, Table B-9, page 41
+        9,
+        0x24,                                   // bDescriptorType = CS_INTERFACE
+        0x03,                                   // bDescriptorSubtype = MIDI_OUT_JACK
+        0x01,                                   // bJackType = EMBEDDED
+        3,                                      // bJackID, ID = 3
+        1,                                      // bNrInputPins = 1 pin
+        2,                                      // BaSourceID(1) = 2
+        1,                                      // BaSourcePin(1) = first pin
+        0,                                      // iJack
+        // MIDI OUT Jack Descriptor, B.4.4, Table B-10, page 41
+        9,
+        0x24,                                   // bDescriptorType = CS_INTERFACE
+        0x03,                                   // bDescriptorSubtype = MIDI_OUT_JACK
+        0x02,                                   // bJackType = EXTERNAL
+        4,                                      // bJackID, ID = 4
+        1,                                      // bNrInputPins = 1 pin
+        1,                                      // BaSourceID(1) = 1
+        1,                                      // BaSourcePin(1) = first pin
+        0,                                      // iJack
+        // Standard Bulk OUT Endpoint Descriptor, B.5.1, Table B-11, pae 42
+        9,                                      // bLength
+        5,                                      // bDescriptorType = ENDPOINT
+        MIDI_RX_ENDPOINT,                       // bEndpointAddress
+        0x02,                                   // bmAttributes (0x02=bulk)
+        MIDI_RX_SIZE, 0,                        // wMaxPacketSize
+        0,                                      // bInterval
+        0,                                      // bRefresh
+        0,                                      // bSynchAddress
+        // Class-specific MS Bulk OUT Endpoint Descriptor, B.5.2, Table B-12, page 42
+        5,                                      // bLength
+        0x25,                                   // bDescriptorSubtype = CS_ENDPOINT
+        0x01,                                   // bJackType = MS_GENERAL
+        1,                                      // bNumEmbMIDIJack = 1 jack
+        1,                                      // BaAssocJackID(1) = jack ID #1
+        // Standard Bulk IN Endpoint Descriptor, B.5.1, Table B-11, pae 42
+        9,                                      // bLength
+        5,                                      // bDescriptorType = ENDPOINT
+        MIDI_TX_ENDPOINT | 0x80,                // bEndpointAddress
+        0x02,                                   // bmAttributes (0x02=bulk)
+        MIDI_TX_SIZE, 0,                        // wMaxPacketSize
+        0,                                      // bInterval
+        0,                                      // bRefresh
+        0,                                      // bSynchAddress
+        // Class-specific MS Bulk IN Endpoint Descriptor, B.5.2, Table B-12, page 42
+        5,                                      // bLength
+        0x25,                                   // bDescriptorSubtype = CS_ENDPOINT
+        0x01,                                   // bJackType = MS_GENERAL
+        1,                                      // bNumEmbMIDIJack = 1 jack
+        3,                                      // BaAssocJackID(1) = jack ID #3
+#endif // MIDI_INTERFACE
+
+#ifdef KEYBOARD_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        KEYBOARD_INTERFACE,                     // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        1,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x01,                                   // bInterfaceSubClass (0x01 = Boot)
+        0x01,                                   // bInterfaceProtocol (0x01 = Keyboard)
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(keyboard_report_desc)),      // wDescriptorLength
+        MSB(sizeof(keyboard_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        KEYBOARD_ENDPOINT | 0x80,               // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        KEYBOARD_SIZE, 0,                       // wMaxPacketSize
+        KEYBOARD_INTERVAL,                      // bInterval
+#endif // KEYBOARD_INTERFACE
+
+#ifdef MOUSE_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        MOUSE_INTERFACE,                        // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        1,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x00,                                   // bInterfaceSubClass (0x01 = Boot)
+        0x00,                                   // bInterfaceProtocol (0x02 = Mouse)
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(mouse_report_desc)),         // wDescriptorLength
+        MSB(sizeof(mouse_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        MOUSE_ENDPOINT | 0x80,                  // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        MOUSE_SIZE, 0,                          // wMaxPacketSize
+        MOUSE_INTERVAL,                         // bInterval
+#endif // MOUSE_INTERFACE
+
+#ifdef RAWHID_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        RAWHID_INTERFACE,                       // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        2,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x00,                                   // bInterfaceSubClass
+        0x00,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(rawhid_report_desc)),        // wDescriptorLength
+        MSB(sizeof(rawhid_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        RAWHID_TX_ENDPOINT | 0x80,              // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        RAWHID_TX_SIZE, 0,                      // wMaxPacketSize
+        RAWHID_TX_INTERVAL,                     // bInterval
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        RAWHID_RX_ENDPOINT,                     // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        RAWHID_RX_SIZE, 0,                      // wMaxPacketSize
+        RAWHID_RX_INTERVAL,			// bInterval
+#endif // RAWHID_INTERFACE
+
+#ifdef FLIGHTSIM_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        FLIGHTSIM_INTERFACE,                    // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        2,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x00,                                   // bInterfaceSubClass
+        0x00,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(flightsim_report_desc)),     // wDescriptorLength
+        MSB(sizeof(flightsim_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        FLIGHTSIM_TX_ENDPOINT | 0x80,           // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        FLIGHTSIM_TX_SIZE, 0,                   // wMaxPacketSize
+        FLIGHTSIM_TX_INTERVAL,                  // bInterval
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        FLIGHTSIM_RX_ENDPOINT,                  // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        FLIGHTSIM_RX_SIZE, 0,                   // wMaxPacketSize
+        FLIGHTSIM_RX_INTERVAL,			// bInterval
+#endif // FLIGHTSIM_INTERFACE
+
+#ifdef SEREMU_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        SEREMU_INTERFACE,                       // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        2,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x00,                                   // bInterfaceSubClass
+        0x00,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(seremu_report_desc)),        // wDescriptorLength
+        MSB(sizeof(seremu_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        SEREMU_TX_ENDPOINT | 0x80,              // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        SEREMU_TX_SIZE, 0,                      // wMaxPacketSize
+        SEREMU_TX_INTERVAL,                     // bInterval
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        SEREMU_RX_ENDPOINT,                     // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        SEREMU_RX_SIZE, 0,                      // wMaxPacketSize
+        SEREMU_RX_INTERVAL,			// bInterval
+#endif // SEREMU_INTERFACE
+
+#ifdef JOYSTICK_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        JOYSTICK_INTERFACE,                     // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        1,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x00,                                   // bInterfaceSubClass
+        0x00,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(joystick_report_desc)),      // wDescriptorLength
+        MSB(sizeof(joystick_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        JOYSTICK_ENDPOINT | 0x80,               // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        JOYSTICK_SIZE, 0,                       // wMaxPacketSize
+        JOYSTICK_INTERVAL,                      // bInterval
+#endif // JOYSTICK_INTERFACE
+
+#ifdef MTP_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        MTP_INTERFACE,                          // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        3,                                      // bNumEndpoints
+        0x06,                                   // bInterfaceClass (0x06 = still image)
+        0x01,                                   // bInterfaceSubClass
+        0x01,                                   // bInterfaceProtocol
+        4,                                      // iInterface
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        MTP_TX_ENDPOINT | 0x80,                 // bEndpointAddress
+        0x02,                                   // bmAttributes (0x02=bulk)
+        MTP_TX_SIZE, 0,                         // wMaxPacketSize
+        0,                                      // bInterval
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        MTP_RX_ENDPOINT,                        // bEndpointAddress
+        0x02,                                   // bmAttributes (0x02=bulk)
+        MTP_RX_SIZE, 0,                         // wMaxPacketSize
+        0,                                      // bInterval
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        MTP_EVENT_ENDPOINT | 0x80,              // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        MTP_EVENT_SIZE, 0,                      // wMaxPacketSize
+        MTP_EVENT_INTERVAL,                     // bInterval
+#endif // MTP_INTERFACE
+
+#ifdef KEYMEDIA_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        KEYMEDIA_INTERFACE,                     // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        1,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x00,                                   // bInterfaceSubClass
+        0x00,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(keymedia_report_desc)),      // wDescriptorLength
+        MSB(sizeof(keymedia_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        KEYMEDIA_ENDPOINT | 0x80,               // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        KEYMEDIA_SIZE, 0,                       // wMaxPacketSize
+        KEYMEDIA_INTERVAL,                      // bInterval
+#endif // KEYMEDIA_INTERFACE
+
+#ifdef AUDIO_INTERFACE
+        // interface association descriptor, USB ECN, Table 9-Z
+        8,                                      // bLength
+        11,                                     // bDescriptorType
+        AUDIO_INTERFACE,                        // bFirstInterface
+        3,                                      // bInterfaceCount
+        0x01,                                   // bFunctionClass
+        0x01,                                   // bFunctionSubClass
+        0x00,                                   // bFunctionProtocol
+        0,                                      // iFunction
+	// Standard AudioControl (AC) Interface Descriptor
+	// USB DCD for Audio Devices 1.0, Table 4-1, page 36
+	9,					// bLength
+	4,					// bDescriptorType, 4 = INTERFACE
+	AUDIO_INTERFACE,			// bInterfaceNumber
+	0,					// bAlternateSetting
+	0,					// bNumEndpoints
+	1,					// bInterfaceClass, 1 = AUDIO
+	1,					// bInterfaceSubclass, 1 = AUDIO_CONTROL
+	0,					// bInterfaceProtocol
+	0,					// iInterface
+	// Class-specific AC Interface Header Descriptor
+	// USB DCD for Audio Devices 1.0, Table 4-2, page 37-38
+	10,					// bLength
+	0x24,					// bDescriptorType, 0x24 = CS_INTERFACE
+	0x01,					// bDescriptorSubtype, 1 = HEADER
+	0x00, 0x01,				// bcdADC (version 1.0)
+	LSB(62), MSB(62),			// wTotalLength
+	2,					// bInCollection
+	AUDIO_INTERFACE+1,			// baInterfaceNr(1) - Transmit to PC
+	AUDIO_INTERFACE+2,			// baInterfaceNr(2) - Receive from PC
+	// Input Terminal Descriptor
+	// USB DCD for Audio Devices 1.0, Table 4-3, page 39
+	12,					// bLength
+	0x24,					// bDescriptorType, 0x24 = CS_INTERFACE
+	0x02,					// bDescriptorSubType, 2 = INPUT_TERMINAL
+	1,					// bTerminalID
+	//0x01, 0x02,				// wTerminalType, 0x0201 = MICROPHONE
+	//0x03, 0x06,				// wTerminalType, 0x0603 = Line Connector
+	0x02, 0x06,				// wTerminalType, 0x0602 = Digital Audio
+	0,					// bAssocTerminal, 0 = unidirectional
+	2,					// bNrChannels
+	0x03, 0x00,				// wChannelConfig, 0x0003 = Left & Right Front
+	0,					// iChannelNames
+	0, 					// iTerminal
+	// Output Terminal Descriptor
+	// USB DCD for Audio Devices 1.0, Table 4-4, page 40
+	9,					// bLength
+	0x24,					// bDescriptorType, 0x24 = CS_INTERFACE
+	3,					// bDescriptorSubtype, 3 = OUTPUT_TERMINAL
+	2,					// bTerminalID
+	0x01, 0x01,				// wTerminalType, 0x0101 = USB_STREAMING
+	0,					// bAssocTerminal, 0 = unidirectional
+	1,					// bCSourceID, connected to input terminal, ID=1
+	0,					// iTerminal
+	// Input Terminal Descriptor
+	// USB DCD for Audio Devices 1.0, Table 4-3, page 39
+	12,					// bLength
+	0x24,					// bDescriptorType, 0x24 = CS_INTERFACE
+	2,					// bDescriptorSubType, 2 = INPUT_TERMINAL
+	3,					// bTerminalID
+	0x01, 0x01,				// wTerminalType, 0x0101 = USB_STREAMING
+	0,					// bAssocTerminal, 0 = unidirectional
+	2,					// bNrChannels
+	0x03, 0x00,				// wChannelConfig, 0x0003 = Left & Right Front
+	0,					// iChannelNames
+	0, 					// iTerminal
+	// Volume feature descriptor
+	10,					// bLength
+	0x24, 				// bDescriptorType = CS_INTERFACE
+	0x06, 				// bDescriptorSubType = FEATURE_UNIT
+	0x31, 				// bUnitID
+	0x03, 				// bSourceID (Input Terminal)
+	0x01, 				// bControlSize (each channel is 1 byte, 3 channels)
+	0x01, 				// bmaControls(0) Master: Mute
+	0x02, 				// bmaControls(1) Left: Volume
+	0x02, 				// bmaControls(2) Right: Volume
+	0x00,				// iFeature
+	// Output Terminal Descriptor
+	// USB DCD for Audio Devices 1.0, Table 4-4, page 40
+	9,					// bLength
+	0x24,					// bDescriptorType, 0x24 = CS_INTERFACE
+	3,					// bDescriptorSubtype, 3 = OUTPUT_TERMINAL
+	4,					// bTerminalID
+	//0x02, 0x03,				// wTerminalType, 0x0302 = Headphones
+	0x02, 0x06,				// wTerminalType, 0x0602 = Digital Audio
+	0,					// bAssocTerminal, 0 = unidirectional
+	0x31,				// bCSourceID, connected to feature, ID=31
+	0,					// iTerminal
+	// Standard AS Interface Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.5.1, Table 4-18, page 59
+	// Alternate 0: default setting, disabled zero bandwidth
+	9,					// bLenght
+	4,					// bDescriptorType = INTERFACE
+	AUDIO_INTERFACE+1,			// bInterfaceNumber
+	0,					// bAlternateSetting
+	0,					// bNumEndpoints
+	1,					// bInterfaceClass, 1 = AUDIO
+	2,					// bInterfaceSubclass, 2 = AUDIO_STREAMING
+	0,					// bInterfaceProtocol
+	0,					// iInterface
+	// Alternate 1: streaming data
+	9,					// bLenght
+	4,					// bDescriptorType = INTERFACE
+	AUDIO_INTERFACE+1,			// bInterfaceNumber
+	1,					// bAlternateSetting
+	1,					// bNumEndpoints
+	1,					// bInterfaceClass, 1 = AUDIO
+	2,					// bInterfaceSubclass, 2 = AUDIO_STREAMING
+	0,					// bInterfaceProtocol
+	0,					// iInterface
+	// Class-Specific AS Interface Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.5.2, Table 4-19, page 60
+	7, 					// bLength
+	0x24,					// bDescriptorType = CS_INTERFACE
+	1,					// bDescriptorSubtype, 1 = AS_GENERAL
+	2,					// bTerminalLink: Terminal ID = 2
+	3,					// bDelay (approx 3ms delay, audio lib updates)
+	0x01, 0x00,				// wFormatTag, 0x0001 = PCM
+	// Type I Format Descriptor
+	// USB DCD for Audio Data Formats 1.0, Section 2.2.5, Table 2-1, page 10
+	11,					// bLength
+	0x24,					// bDescriptorType = CS_INTERFACE
+	2,					// bDescriptorSubtype = FORMAT_TYPE
+	1,					// bFormatType = FORMAT_TYPE_I
+	2,					// bNrChannels = 2
+	2,					// bSubFrameSize = 2 byte
+	16,					// bBitResolution = 16 bits
+	1,					// bSamFreqType = 1 frequency
+	LSB(44100), MSB(44100), 0,		// tSamFreq
+	// Standard AS Isochronous Audio Data Endpoint Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.6.1.1, Table 4-20, page 61-62
+	9, 					// bLength
+	5, 					// bDescriptorType, 5 = ENDPOINT_DESCRIPTOR
+	AUDIO_TX_ENDPOINT | 0x80,		// bEndpointAddress
+	0x09, 					// bmAttributes = isochronous, adaptive
+	LSB(AUDIO_TX_SIZE), MSB(AUDIO_TX_SIZE),	// wMaxPacketSize
+	1,			 		// bInterval, 1 = every frame
+	0,					// bRefresh
+	0,					// bSynchAddress
+	// Class-Specific AS Isochronous Audio Data Endpoint Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.6.1.2, Table 4-21, page 62-63
+	7,  					// bLength
+	0x25,  					// bDescriptorType, 0x25 = CS_ENDPOINT
+	1,  					// bDescriptorSubtype, 1 = EP_GENERAL
+	0x00,  					// bmAttributes
+	0,  					// bLockDelayUnits, 1 = ms
+	0x00, 0x00,  				// wLockDelay
+	// Standard AS Interface Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.5.1, Table 4-18, page 59
+	// Alternate 0: default setting, disabled zero bandwidth
+	9,					// bLenght
+	4,					// bDescriptorType = INTERFACE
+	AUDIO_INTERFACE+2,			// bInterfaceNumber
+	0,					// bAlternateSetting
+	0,					// bNumEndpoints
+	1,					// bInterfaceClass, 1 = AUDIO
+	2,					// bInterfaceSubclass, 2 = AUDIO_STREAMING
+	0,					// bInterfaceProtocol
+	0,					// iInterface
+	// Alternate 1: streaming data
+	9,					// bLenght
+	4,					// bDescriptorType = INTERFACE
+	AUDIO_INTERFACE+2,			// bInterfaceNumber
+	1,					// bAlternateSetting
+	2,					// bNumEndpoints
+	1,					// bInterfaceClass, 1 = AUDIO
+	2,					// bInterfaceSubclass, 2 = AUDIO_STREAMING
+	0,					// bInterfaceProtocol
+	0,					// iInterface
+	// Class-Specific AS Interface Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.5.2, Table 4-19, page 60
+	7, 					// bLength
+	0x24,					// bDescriptorType = CS_INTERFACE
+	1,					// bDescriptorSubtype, 1 = AS_GENERAL
+	3,					// bTerminalLink: Terminal ID = 3
+	3,					// bDelay (approx 3ms delay, audio lib updates)
+	0x01, 0x00,				// wFormatTag, 0x0001 = PCM
+	// Type I Format Descriptor
+	// USB DCD for Audio Data Formats 1.0, Section 2.2.5, Table 2-1, page 10
+	11,					// bLength
+	0x24,					// bDescriptorType = CS_INTERFACE
+	2,					// bDescriptorSubtype = FORMAT_TYPE
+	1,					// bFormatType = FORMAT_TYPE_I
+	2,					// bNrChannels = 2
+	2,					// bSubFrameSize = 2 byte
+	16,					// bBitResolution = 16 bits
+	1,					// bSamFreqType = 1 frequency
+	LSB(44100), MSB(44100), 0,		// tSamFreq
+	// Standard AS Isochronous Audio Data Endpoint Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.6.1.1, Table 4-20, page 61-62
+	9, 					// bLength
+	5, 					// bDescriptorType, 5 = ENDPOINT_DESCRIPTOR
+	AUDIO_RX_ENDPOINT,			// bEndpointAddress
+	0x05, 					// bmAttributes = isochronous, asynchronous
+	LSB(AUDIO_RX_SIZE), MSB(AUDIO_RX_SIZE),	// wMaxPacketSize
+	1,			 		// bInterval, 1 = every frame
+	0,					// bRefresh
+	AUDIO_SYNC_ENDPOINT | 0x80,		// bSynchAddress
+	// Class-Specific AS Isochronous Audio Data Endpoint Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.6.1.2, Table 4-21, page 62-63
+	7,  					// bLength
+	0x25,  					// bDescriptorType, 0x25 = CS_ENDPOINT
+	1,  					// bDescriptorSubtype, 1 = EP_GENERAL
+	0x00,  					// bmAttributes
+	0,  					// bLockDelayUnits, 1 = ms
+	0x00, 0x00,  				// wLockDelay
+	// Standard AS Isochronous Audio Synch Endpoint Descriptor
+	// USB DCD for Audio Devices 1.0, Section 4.6.2.1, Table 4-22, page 63-64
+	9, 					// bLength
+	5, 					// bDescriptorType, 5 = ENDPOINT_DESCRIPTOR
+	AUDIO_SYNC_ENDPOINT | 0x80,		// bEndpointAddress
+	0x11, 					// bmAttributes = isochronous, feedback
+	3, 0,					// wMaxPacketSize, 3 bytes
+	1,			 		// bInterval, 1 = every frame
+	5,					// bRefresh, 5 = 32ms
+	0,					// bSynchAddress
+#endif
+
+#ifdef MULTITOUCH_INTERFACE
+        // interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
+        9,                                      // bLength
+        4,                                      // bDescriptorType
+        MULTITOUCH_INTERFACE,                   // bInterfaceNumber
+        0,                                      // bAlternateSetting
+        1,                                      // bNumEndpoints
+        0x03,                                   // bInterfaceClass (0x03 = HID)
+        0x00,                                   // bInterfaceSubClass
+        0x00,                                   // bInterfaceProtocol
+        0,                                      // iInterface
+        // HID interface descriptor, HID 1.11 spec, section 6.2.1
+        9,                                      // bLength
+        0x21,                                   // bDescriptorType
+        0x11, 0x01,                             // bcdHID
+        0,                                      // bCountryCode
+        1,                                      // bNumDescriptors
+        0x22,                                   // bDescriptorType
+        LSB(sizeof(multitouch_report_desc)),    // wDescriptorLength
+        MSB(sizeof(multitouch_report_desc)),
+        // endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
+        7,                                      // bLength
+        5,                                      // bDescriptorType
+        MULTITOUCH_ENDPOINT | 0x80,             // bEndpointAddress
+        0x03,                                   // bmAttributes (0x03=intr)
+        MULTITOUCH_SIZE, 0,                     // wMaxPacketSize
+        1,                                      // bInterval
+#endif // KEYMEDIA_INTERFACE
+};
+
+
+// **************************************************************
+//   String Descriptors
+// **************************************************************
+
+// The descriptors above can provide human readable strings,
+// referenced by index numbers.  These descriptors are the
+// actual string data
+
+/* defined in usb_names.h
+struct usb_string_descriptor_struct {
+        uint8_t bLength;
+        uint8_t bDescriptorType;
+        uint16_t wString[];
+};
+*/
+
+extern struct usb_string_descriptor_struct usb_string_manufacturer_name
+        __attribute__ ((weak, alias("usb_string_manufacturer_name_default")));
+extern struct usb_string_descriptor_struct usb_string_product_name
+        __attribute__ ((weak, alias("usb_string_product_name_default")));
+extern struct usb_string_descriptor_struct usb_string_serial_number
+        __attribute__ ((weak, alias("usb_string_serial_number_default")));
+
+struct usb_string_descriptor_struct string0 = {
+        4,
+        3,
+        {0x0409}
+};
+
+struct usb_string_descriptor_struct usb_string_manufacturer_name_default = {
+        2 + MANUFACTURER_NAME_LEN * 2,
+        3,
+        MANUFACTURER_NAME
+};
+struct usb_string_descriptor_struct usb_string_product_name_default = {
+	2 + PRODUCT_NAME_LEN * 2,
+        3,
+        PRODUCT_NAME
+};
+struct usb_string_descriptor_struct usb_string_serial_number_default = {
+        12,
+        3,
+        {0,0,0,0,0,0,0,0,0,0}
+};
+#ifdef MTP_INTERFACE
+struct usb_string_descriptor_struct usb_string_mtp = {
+	2 + 3 * 2,
+	3,
+	{'M','T','P'}
+};
+#endif
+
+void usb_init_serialnumber(void)
+{
+	char buf[11];
+	uint32_t i, num;
+
+	__disable_irq();
+#if defined(HAS_KINETIS_FLASH_FTFA) || defined(HAS_KINETIS_FLASH_FTFL)
+	FTFL_FSTAT = FTFL_FSTAT_RDCOLERR | FTFL_FSTAT_ACCERR | FTFL_FSTAT_FPVIOL;
+	FTFL_FCCOB0 = 0x41;
+	FTFL_FCCOB1 = 15;
+	FTFL_FSTAT = FTFL_FSTAT_CCIF;
+	while (!(FTFL_FSTAT & FTFL_FSTAT_CCIF)) ; // wait
+	num = *(uint32_t *)&FTFL_FCCOB7;
+#elif defined(HAS_KINETIS_FLASH_FTFE)
+	kinetis_hsrun_disable();
+	FTFL_FSTAT = FTFL_FSTAT_RDCOLERR | FTFL_FSTAT_ACCERR | FTFL_FSTAT_FPVIOL;
+	*(uint32_t *)&FTFL_FCCOB3 = 0x41070000;
+	FTFL_FSTAT = FTFL_FSTAT_CCIF;
+	while (!(FTFL_FSTAT & FTFL_FSTAT_CCIF)) ; // wait
+	num = *(uint32_t *)&FTFL_FCCOBB;
+	kinetis_hsrun_enable();
+#endif
+	__enable_irq();
+	// add extra zero to work around OS-X CDC-ACM driver bug
+	if (num < 10000000) num = num * 10;
+	ultoa(num, buf, 10);
+	for (i=0; i<10; i++) {
+		char c = buf[i];
+		if (!c) break;
+		usb_string_serial_number_default.wString[i] = c;
+	}
+	usb_string_serial_number_default.bLength = i * 2 + 2;
+}
+
+
+// **************************************************************
+//   Descriptors List
+// **************************************************************
+
+// This table provides access to all the descriptor data above.
+
+const usb_descriptor_list_t usb_descriptor_list[] = {
+	//wValue, wIndex, address,          length
+	{0x0100, 0x0000, device_descriptor, sizeof(device_descriptor)},
+	{0x0200, 0x0000, config_descriptor, sizeof(config_descriptor)},
+#ifdef SEREMU_INTERFACE
+	{0x2200, SEREMU_INTERFACE, seremu_report_desc, sizeof(seremu_report_desc)},
+	{0x2100, SEREMU_INTERFACE, config_descriptor+SEREMU_HID_DESC_OFFSET, 9},
+#endif
+#ifdef KEYBOARD_INTERFACE
+        {0x2200, KEYBOARD_INTERFACE, keyboard_report_desc, sizeof(keyboard_report_desc)},
+        {0x2100, KEYBOARD_INTERFACE, config_descriptor+KEYBOARD_HID_DESC_OFFSET, 9},
+#endif
+#ifdef MOUSE_INTERFACE
+        {0x2200, MOUSE_INTERFACE, mouse_report_desc, sizeof(mouse_report_desc)},
+        {0x2100, MOUSE_INTERFACE, config_descriptor+MOUSE_HID_DESC_OFFSET, 9},
+#endif
+#ifdef JOYSTICK_INTERFACE
+        {0x2200, JOYSTICK_INTERFACE, joystick_report_desc, sizeof(joystick_report_desc)},
+        {0x2100, JOYSTICK_INTERFACE, config_descriptor+JOYSTICK_HID_DESC_OFFSET, 9},
+#endif
+#ifdef RAWHID_INTERFACE
+	{0x2200, RAWHID_INTERFACE, rawhid_report_desc, sizeof(rawhid_report_desc)},
+	{0x2100, RAWHID_INTERFACE, config_descriptor+RAWHID_HID_DESC_OFFSET, 9},
+#endif
+#ifdef FLIGHTSIM_INTERFACE
+	{0x2200, FLIGHTSIM_INTERFACE, flightsim_report_desc, sizeof(flightsim_report_desc)},
+	{0x2100, FLIGHTSIM_INTERFACE, config_descriptor+FLIGHTSIM_HID_DESC_OFFSET, 9},
+#endif
+#ifdef KEYMEDIA_INTERFACE
+        {0x2200, KEYMEDIA_INTERFACE, keymedia_report_desc, sizeof(keymedia_report_desc)},
+        {0x2100, KEYMEDIA_INTERFACE, config_descriptor+KEYMEDIA_HID_DESC_OFFSET, 9},
+#endif
+#ifdef MULTITOUCH_INTERFACE
+        {0x2200, MULTITOUCH_INTERFACE, multitouch_report_desc, sizeof(multitouch_report_desc)},
+        {0x2100, MULTITOUCH_INTERFACE, config_descriptor+MULTITOUCH_HID_DESC_OFFSET, 9},
+#endif
+#ifdef MTP_INTERFACE
+	{0x0304, 0x0409, (const uint8_t *)&usb_string_mtp, 0},
+#endif
+        {0x0300, 0x0000, (const uint8_t *)&string0, 0},
+        {0x0301, 0x0409, (const uint8_t *)&usb_string_manufacturer_name, 0},
+        {0x0302, 0x0409, (const uint8_t *)&usb_string_product_name, 0},
+        {0x0303, 0x0409, (const uint8_t *)&usb_string_serial_number, 0},
+	{0, 0, NULL, 0}
+};
+
+
+// **************************************************************
+//   Endpoint Configuration
+// **************************************************************
+
+#if 0
+// 0x00 = not used
+// 0x19 = Recieve only
+// 0x15 = Transmit only
+// 0x1D = Transmit & Recieve
+//
+const uint8_t usb_endpoint_config_table[NUM_ENDPOINTS] =
+{
+	0x00, 0x15, 0x19, 0x15, 0x00, 0x00, 0x00, 0x00,
+	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+};
+#endif
+
+
+const uint8_t usb_endpoint_config_table[NUM_ENDPOINTS] =
+{
+#if (defined(ENDPOINT1_CONFIG) && NUM_ENDPOINTS >= 1)
+	ENDPOINT1_CONFIG,
+#elif (NUM_ENDPOINTS >= 1)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT2_CONFIG) && NUM_ENDPOINTS >= 2)
+	ENDPOINT2_CONFIG,
+#elif (NUM_ENDPOINTS >= 2)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT3_CONFIG) && NUM_ENDPOINTS >= 3)
+	ENDPOINT3_CONFIG,
+#elif (NUM_ENDPOINTS >= 3)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT4_CONFIG) && NUM_ENDPOINTS >= 4)
+	ENDPOINT4_CONFIG,
+#elif (NUM_ENDPOINTS >= 4)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT5_CONFIG) && NUM_ENDPOINTS >= 5)
+	ENDPOINT5_CONFIG,
+#elif (NUM_ENDPOINTS >= 5)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT6_CONFIG) && NUM_ENDPOINTS >= 6)
+	ENDPOINT6_CONFIG,
+#elif (NUM_ENDPOINTS >= 6)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT7_CONFIG) && NUM_ENDPOINTS >= 7)
+	ENDPOINT7_CONFIG,
+#elif (NUM_ENDPOINTS >= 7)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT8_CONFIG) && NUM_ENDPOINTS >= 8)
+	ENDPOINT8_CONFIG,
+#elif (NUM_ENDPOINTS >= 8)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT9_CONFIG) && NUM_ENDPOINTS >= 9)
+	ENDPOINT9_CONFIG,
+#elif (NUM_ENDPOINTS >= 9)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT10_CONFIG) && NUM_ENDPOINTS >= 10)
+	ENDPOINT10_CONFIG,
+#elif (NUM_ENDPOINTS >= 10)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT11_CONFIG) && NUM_ENDPOINTS >= 11)
+	ENDPOINT11_CONFIG,
+#elif (NUM_ENDPOINTS >= 11)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT12_CONFIG) && NUM_ENDPOINTS >= 12)
+	ENDPOINT12_CONFIG,
+#elif (NUM_ENDPOINTS >= 12)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT13_CONFIG) && NUM_ENDPOINTS >= 13)
+	ENDPOINT13_CONFIG,
+#elif (NUM_ENDPOINTS >= 13)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT14_CONFIG) && NUM_ENDPOINTS >= 14)
+	ENDPOINT14_CONFIG,
+#elif (NUM_ENDPOINTS >= 14)
+	ENDPOINT_UNUSED,
+#endif
+#if (defined(ENDPOINT15_CONFIG) && NUM_ENDPOINTS >= 15)
+	ENDPOINT15_CONFIG,
+#elif (NUM_ENDPOINTS >= 15)
+	ENDPOINT_UNUSED,
+#endif
+};
+
+
+#endif // NUM_ENDPOINTS
+#endif // F_CPU >= 20 MHz
diff --git a/motors/usb/usb_desc.h b/motors/usb/usb_desc.h
new file mode 100644
index 0000000..b59640d
--- /dev/null
+++ b/motors/usb/usb_desc.h
@@ -0,0 +1,711 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef _usb_desc_h_
+#define _usb_desc_h_
+
+// This header is NOT meant to be included when compiling
+// user sketches in Arduino.  The low-level functions
+// provided by usb_dev.c are meant to be called only by
+// code which provides higher-level interfaces to the user.
+
+#include <stdint.h>
+#include <stddef.h>
+
+#define ENDPOINT_UNUSED			0x00
+#define ENDPOINT_TRANSIMIT_ONLY		0x15
+#define ENDPOINT_RECEIVE_ONLY		0x19
+#define ENDPOINT_TRANSMIT_AND_RECEIVE	0x1D
+#define ENDPOINT_RECEIVE_ISOCHRONOUS	0x18
+#define ENDPOINT_TRANSMIT_ISOCHRONOUS	0x14
+
+/*
+Each group of #define lines below corresponds to one of the
+settings in the Tools > USB Type menu.  This file defines what
+type of USB device is actually created for each of those menu
+options.
+
+Each "interface" is a set of functionality your PC or Mac will
+use and treat as if it is a unique device.  Within each interface,
+the "endpoints" are the actual communication channels.  Most
+interfaces use 1, 2 or 3 endpoints.  By editing only this file,
+you can customize the USB Types to be any collection of interfaces.
+
+To modify a USB Type, delete the XYZ_INTERFACE lines for any
+interfaces you wish to remove, and copy them from another USB Type
+for any you want to add.
+
+Give each interface a unique number, and edit NUM_INTERFACE to
+reflect the total number of interfaces.
+
+Next, assign unique endpoint numbers to all the endpoints across
+all the interfaces your device has.  You can reuse an endpoint
+number for transmit and receive, but the same endpoint number must
+not be used twice to transmit, or twice to receive.
+
+Most endpoints also require their maximum size, and some also
+need an interval specification (the number of milliseconds the
+PC will check for data from that endpoint).  For existing
+interfaces, usually these other settings should not be changed.
+
+Edit NUM_ENDPOINTS to be at least the largest endpoint number used.
+
+Edit NUM_USB_BUFFERS to control how much memory the USB stack will
+allocate.  At least 2 should be used for each endpoint.  More
+memory will allow higher throughput for user programs that have
+high latency (eg, spending time doing things other than interacting
+with the USB).
+
+Edit the ENDPOINT*_CONFIG lines so each endpoint is configured
+the proper way (transmit, receive, or both).
+
+If you are using existing interfaces (making your own device with
+a different set of interfaces) the code in all other files should
+automatically adapt to the new endpoints you specify here.
+
+If you need to create a new type of interface, you'll need to write
+the code which sends and receives packets, and presents an API to
+the user.  Usually, a pair of files are added for the actual code,
+and code is also added in usb_dev.c for any control transfers,
+interrupt-level code, or other very low-level stuff not possible
+from the packet send/receive functons.  Code also is added in
+usb_inst.c to create an instance of your C++ object.
+
+You may edit the Vendor and Product ID numbers, and strings.  If
+the numbers are changed, Teensyduino may not be able to automatically
+find and reboot your board when you click the Upload button in
+the Arduino IDE.  You will need to press the Program button on
+Teensy to initiate programming.
+
+Some operating systems, especially Windows, may cache USB device
+info.  Changes to the device name may not update on the same
+computer unless the vendor or product ID numbers change, or the
+"bcdDevice" revision code is increased.
+
+If these instructions are missing steps or could be improved, please
+let me know?  http://forum.pjrc.com/forums/4-Suggestions-amp-Bug-Reports
+*/
+
+
+#if defined(USB_SERIAL)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0483
+  #define DEVICE_CLASS		2	// 2 = Communication Class
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'U','S','B',' ','S','e','r','i','a','l'}
+  #define PRODUCT_NAME_LEN	10
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS		4
+  #define NUM_USB_BUFFERS	12
+  #define NUM_INTERFACE		2
+  #define CDC_STATUS_INTERFACE	0
+  #define CDC_DATA_INTERFACE	1
+  #define CDC_ACM_ENDPOINT	2
+  #define CDC_RX_ENDPOINT       3
+  #define CDC_TX_ENDPOINT       4
+  #define CDC_ACM_SIZE          16
+  #define CDC_RX_SIZE           64
+  #define CDC_TX_SIZE           64
+  #define ENDPOINT2_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+#elif defined(USB_KEYBOARDONLY)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x04D0
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'K','e','y','b','o','a','r','d'}
+  #define PRODUCT_NAME_LEN	8
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         4
+  #define NUM_USB_BUFFERS	14
+  #define NUM_INTERFACE		3
+  #define SEREMU_INTERFACE      1	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define KEYBOARD_INTERFACE    0	// Keyboard
+  #define KEYBOARD_ENDPOINT     3
+  #define KEYBOARD_SIZE         8
+  #define KEYBOARD_INTERVAL     1
+  #define KEYMEDIA_INTERFACE    2	// Keyboard Media Keys
+  #define KEYMEDIA_ENDPOINT     4
+  #define KEYMEDIA_SIZE         8
+  #define KEYMEDIA_INTERVAL     4
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT6_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+#elif defined(USB_HID)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0482
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'K','e','y','b','o','a','r','d','/','M','o','u','s','e','/','J','o','y','s','t','i','c','k'}
+  #define PRODUCT_NAME_LEN	23
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         6
+  #define NUM_USB_BUFFERS	24
+  #define NUM_INTERFACE		5
+  #define SEREMU_INTERFACE      2	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define KEYBOARD_INTERFACE    0	// Keyboard
+  #define KEYBOARD_ENDPOINT     3
+  #define KEYBOARD_SIZE         8
+  #define KEYBOARD_INTERVAL     1
+  #define KEYMEDIA_INTERFACE    4	// Keyboard Media Keys
+  #define KEYMEDIA_ENDPOINT     6
+  #define KEYMEDIA_SIZE         8
+  #define KEYMEDIA_INTERVAL     4
+  #define MOUSE_INTERFACE       1	// Mouse
+  #define MOUSE_ENDPOINT        5
+  #define MOUSE_SIZE            8
+  #define MOUSE_INTERVAL        1
+  #define JOYSTICK_INTERFACE    3	// Joystick
+  #define JOYSTICK_ENDPOINT     4
+  #define JOYSTICK_SIZE         12	//  12 = normal, 64 = extreme joystick
+  #define JOYSTICK_INTERVAL     2
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT6_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+#elif defined(USB_SERIAL_HID)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0487
+  #define DEVICE_CLASS		0xEF
+  #define DEVICE_SUBCLASS	0x02
+  #define DEVICE_PROTOCOL	0x01
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'S','e','r','i','a','l','/','K','e','y','b','o','a','r','d','/','M','o','u','s','e','/','J','o','y','s','t','i','c','k'}
+  #define PRODUCT_NAME_LEN	30
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS		7
+  #define NUM_USB_BUFFERS	30
+  #define NUM_INTERFACE		6
+  #define CDC_IAD_DESCRIPTOR	1
+  #define CDC_STATUS_INTERFACE	0
+  #define CDC_DATA_INTERFACE	1	// Serial
+  #define CDC_ACM_ENDPOINT	2
+  #define CDC_RX_ENDPOINT       3
+  #define CDC_TX_ENDPOINT       4
+  #define CDC_ACM_SIZE          16
+  #define CDC_RX_SIZE           64
+  #define CDC_TX_SIZE           64
+  #define KEYBOARD_INTERFACE    2	// Keyboard
+  #define KEYBOARD_ENDPOINT     1
+  #define KEYBOARD_SIZE         8
+  #define KEYBOARD_INTERVAL     1
+  #define KEYMEDIA_INTERFACE    5	// Keyboard Media Keys
+  #define KEYMEDIA_ENDPOINT     7
+  #define KEYMEDIA_SIZE         8
+  #define KEYMEDIA_INTERVAL     4
+  #define MOUSE_INTERFACE       3	// Mouse
+  #define MOUSE_ENDPOINT        5
+  #define MOUSE_SIZE            8
+  #define MOUSE_INTERVAL        2
+  #define JOYSTICK_INTERFACE    4	// Joystick
+  #define JOYSTICK_ENDPOINT     6
+  #define JOYSTICK_SIZE         12	//  12 = normal, 64 = extreme joystick
+  #define JOYSTICK_INTERVAL     1
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT6_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT7_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+#elif defined(USB_TOUCHSCREEN)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x04D3
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'K','e','y','b','o','a','r','d','/','T','o','u','c','h','s','c','r','e','e','n'}
+  #define PRODUCT_NAME_LEN	20
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         5
+  #define NUM_USB_BUFFERS	15
+  #define NUM_INTERFACE		4
+  #define SEREMU_INTERFACE      1	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define KEYBOARD_INTERFACE    0	// Keyboard
+  #define KEYBOARD_ENDPOINT     3
+  #define KEYBOARD_SIZE         8
+  #define KEYBOARD_INTERVAL     1
+  #define KEYMEDIA_INTERFACE    2	// Keyboard Media Keys
+  #define KEYMEDIA_ENDPOINT     4
+  #define KEYMEDIA_SIZE         8
+  #define KEYMEDIA_INTERVAL     4
+  #define MULTITOUCH_INTERFACE  3	// Touchscreen
+  #define MULTITOUCH_ENDPOINT   5
+  #define MULTITOUCH_SIZE       9
+  #define MULTITOUCH_FINGERS    10
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+#elif defined(USB_HID_TOUCHSCREEN)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x04D4
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'K','e','y','b','o','a','r','d','/','M','o','u','s','e','/','T','o','u','c','h','s','c','r','e','e','n'}
+  #define PRODUCT_NAME_LEN	26
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         6
+  #define NUM_USB_BUFFERS	20
+  #define NUM_INTERFACE		5
+  #define SEREMU_INTERFACE      2	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define KEYBOARD_INTERFACE    0	// Keyboard
+  #define KEYBOARD_ENDPOINT     3
+  #define KEYBOARD_SIZE         8
+  #define KEYBOARD_INTERVAL     1
+  #define KEYMEDIA_INTERFACE    3	// Keyboard Media Keys
+  #define KEYMEDIA_ENDPOINT     4
+  #define KEYMEDIA_SIZE         8
+  #define KEYMEDIA_INTERVAL     4
+  #define MOUSE_INTERFACE       1	// Mouse
+  #define MOUSE_ENDPOINT        6
+  #define MOUSE_SIZE            8
+  #define MOUSE_INTERVAL        2
+  #define MULTITOUCH_INTERFACE  4	// Touchscreen
+  #define MULTITOUCH_ENDPOINT   5
+  #define MULTITOUCH_SIZE       9
+  #define MULTITOUCH_FINGERS    10
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT6_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+#elif defined(USB_MIDI)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0485
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y',' ','M','I','D','I'}
+  #define PRODUCT_NAME_LEN	11
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         4
+  #define NUM_USB_BUFFERS	16
+  #define NUM_INTERFACE		2
+  #define SEREMU_INTERFACE      1	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define MIDI_INTERFACE        0	// MIDI
+  #define MIDI_TX_ENDPOINT      3
+  #define MIDI_TX_SIZE          64
+  #define MIDI_RX_ENDPOINT      4
+  #define MIDI_RX_SIZE          64
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_ONLY
+
+#elif defined(USB_MIDI_SERIAL)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0489
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y',' ','M','I','D','I'}
+  #define PRODUCT_NAME_LEN	11
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         5
+  #define NUM_USB_BUFFERS	30
+  #define NUM_INTERFACE		3
+  #define CDC_IAD_DESCRIPTOR	1
+  #define CDC_STATUS_INTERFACE	0
+  #define CDC_DATA_INTERFACE	1	// Serial
+  #define CDC_ACM_ENDPOINT	1
+  #define CDC_RX_ENDPOINT       2
+  #define CDC_TX_ENDPOINT       3
+  #define CDC_ACM_SIZE          16
+  #define CDC_RX_SIZE           64
+  #define CDC_TX_SIZE           64
+  #define MIDI_INTERFACE        2	// MIDI
+  #define MIDI_TX_ENDPOINT      4
+  #define MIDI_TX_SIZE          64
+  #define MIDI_RX_ENDPOINT      5
+  #define MIDI_RX_SIZE          64
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_RECEIVE_ONLY
+
+#elif defined(USB_RAWHID)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0486
+  #define RAWHID_USAGE_PAGE	0xFFAB  // recommended: 0xFF00 to 0xFFFF
+  #define RAWHID_USAGE		0x0200  // recommended: 0x0100 to 0xFFFF
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y','d','u','i','n','o',' ','R','a','w','H','I','D'}
+  #define PRODUCT_NAME_LEN	18
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         4
+  #define NUM_USB_BUFFERS	12
+  #define NUM_INTERFACE		2
+  #define RAWHID_INTERFACE      0	// RawHID
+  #define RAWHID_TX_ENDPOINT    3
+  #define RAWHID_TX_SIZE        64
+  #define RAWHID_TX_INTERVAL    1
+  #define RAWHID_RX_ENDPOINT    4
+  #define RAWHID_RX_SIZE        64
+  #define RAWHID_RX_INTERVAL    1
+  #define SEREMU_INTERFACE      1	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_ONLY
+
+#elif defined(USB_FLIGHTSIM)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0488
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y',' ','F','l','i','g','h','t',' ','S','i','m',' ','C','o','n','t','r','o','l','s'}
+  #define PRODUCT_NAME_LEN	26
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         4
+  #define NUM_USB_BUFFERS	20
+  #define NUM_INTERFACE		2
+  #define FLIGHTSIM_INTERFACE	0	// Flight Sim Control
+  #define FLIGHTSIM_TX_ENDPOINT	3
+  #define FLIGHTSIM_TX_SIZE	64
+  #define FLIGHTSIM_TX_INTERVAL	1
+  #define FLIGHTSIM_RX_ENDPOINT	4
+  #define FLIGHTSIM_RX_SIZE	64
+  #define FLIGHTSIM_RX_INTERVAL	1
+  #define SEREMU_INTERFACE      1	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_ONLY
+
+#elif defined(USB_FLIGHTSIM_JOYSTICK)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x04D9
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y',' ','F','l','i','g','h','t',' ','S','i','m',' ','C','o','n','t','r','o','l','s'}
+  #define PRODUCT_NAME_LEN	26
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         5
+  #define NUM_USB_BUFFERS	20
+  #define NUM_INTERFACE		3
+  #define FLIGHTSIM_INTERFACE	0	// Flight Sim Control
+  #define FLIGHTSIM_TX_ENDPOINT	3
+  #define FLIGHTSIM_TX_SIZE	64
+  #define FLIGHTSIM_TX_INTERVAL	1
+  #define FLIGHTSIM_RX_ENDPOINT	4
+  #define FLIGHTSIM_RX_SIZE	64
+  #define FLIGHTSIM_RX_INTERVAL	1
+  #define SEREMU_INTERFACE      1	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define JOYSTICK_INTERFACE    2	// Joystick
+  #define JOYSTICK_ENDPOINT     5
+  #define JOYSTICK_SIZE         12	//  12 = normal, 64 = extreme joystick
+  #define JOYSTICK_INTERVAL     1
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+
+#elif defined(USB_MTPDISK)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x04D1
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y',' ','M','T','P',' ','D','i','s','k'}
+  #define PRODUCT_NAME_LEN	15
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         4
+  #define NUM_USB_BUFFERS	20
+  #define NUM_INTERFACE		2
+  #define MTP_INTERFACE		0	// MTP Disk
+  #define MTP_TX_ENDPOINT	3
+  #define MTP_TX_SIZE		64
+  #define MTP_RX_ENDPOINT	3
+  #define MTP_RX_SIZE		64
+  #define MTP_EVENT_ENDPOINT	4
+  #define MTP_EVENT_SIZE	16
+  #define MTP_EVENT_INTERVAL	10
+  #define SEREMU_INTERFACE      1	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSMIT_AND_RECEIVE
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_ONLY
+
+#elif defined(USB_AUDIO)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x04D2
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y',' ','A','u','d','i','o'}
+  #define PRODUCT_NAME_LEN	12
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         5
+  #define NUM_USB_BUFFERS	16
+  #define NUM_INTERFACE		4
+  #define SEREMU_INTERFACE      0	// Serial emulation
+  #define SEREMU_TX_ENDPOINT    1
+  #define SEREMU_TX_SIZE        64
+  #define SEREMU_TX_INTERVAL    1
+  #define SEREMU_RX_ENDPOINT    2
+  #define SEREMU_RX_SIZE        32
+  #define SEREMU_RX_INTERVAL    2
+  #define AUDIO_INTERFACE	1	// Audio (uses 3 consecutive interfaces)
+  #define AUDIO_TX_ENDPOINT     3
+  #define AUDIO_TX_SIZE         180
+  #define AUDIO_RX_ENDPOINT     4
+  #define AUDIO_RX_SIZE         180
+  #define AUDIO_SYNC_ENDPOINT	5
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSMIT_ISOCHRONOUS
+  #define ENDPOINT4_CONFIG	ENDPOINT_RECEIVE_ISOCHRONOUS
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSMIT_ISOCHRONOUS
+
+#elif defined(USB_MIDI_AUDIO_SERIAL)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x048A
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'T','e','e','n','s','y',' ','M','I','D','I','/','A','u','d','i','o'}
+  #define PRODUCT_NAME_LEN	17
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         8
+  #define NUM_USB_BUFFERS	30
+  #define NUM_INTERFACE		6
+  #define CDC_IAD_DESCRIPTOR	1
+  #define CDC_STATUS_INTERFACE	0
+  #define CDC_DATA_INTERFACE	1	// Serial
+  #define CDC_ACM_ENDPOINT	1
+  #define CDC_RX_ENDPOINT       2
+  #define CDC_TX_ENDPOINT       3
+  #define CDC_ACM_SIZE          16
+  #define CDC_RX_SIZE           64
+  #define CDC_TX_SIZE           64
+  #define MIDI_INTERFACE        2	// MIDI
+  #define MIDI_TX_ENDPOINT      4
+  #define MIDI_TX_SIZE          64
+  #define MIDI_RX_ENDPOINT      5
+  #define MIDI_RX_SIZE          64
+  #define AUDIO_INTERFACE	3	// Audio (uses 3 consecutive interfaces)
+  #define AUDIO_TX_ENDPOINT     6
+  #define AUDIO_TX_SIZE         180
+  #define AUDIO_RX_ENDPOINT     7
+  #define AUDIO_RX_SIZE         180
+  #define AUDIO_SYNC_ENDPOINT	8
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_RECEIVE_ONLY
+  #define ENDPOINT6_CONFIG	ENDPOINT_TRANSMIT_ISOCHRONOUS
+  #define ENDPOINT7_CONFIG	ENDPOINT_RECEIVE_ISOCHRONOUS
+  #define ENDPOINT8_CONFIG	ENDPOINT_TRANSMIT_ISOCHRONOUS
+
+#elif defined(USB_EVERYTHING)
+  #define VENDOR_ID		0x16C0
+  #define PRODUCT_ID		0x0476
+  #define RAWHID_USAGE_PAGE	0xFFAB  // recommended: 0xFF00 to 0xFFFF
+  #define RAWHID_USAGE		0x0200  // recommended: 0x0100 to 0xFFFF
+  #define DEVICE_CLASS		0xEF
+  #define DEVICE_SUBCLASS	0x02
+  #define DEVICE_PROTOCOL	0x01
+  #define MANUFACTURER_NAME	{'T','e','e','n','s','y','d','u','i','n','o'}
+  #define MANUFACTURER_NAME_LEN	11
+  #define PRODUCT_NAME		{'A','l','l',' ','T','h','e',' ','T','h','i','n','g','s'}
+  #define PRODUCT_NAME_LEN	14
+  #define EP0_SIZE		64
+  #define NUM_ENDPOINTS         15
+  #define NUM_USB_BUFFERS	31
+  #define NUM_INTERFACE		13
+  #define CDC_IAD_DESCRIPTOR	1
+  #define CDC_STATUS_INTERFACE	0
+  #define CDC_DATA_INTERFACE	1	// Serial
+  #define CDC_ACM_ENDPOINT	1
+  #define CDC_RX_ENDPOINT       2
+  #define CDC_TX_ENDPOINT       2
+  #define CDC_ACM_SIZE          16
+  #define CDC_RX_SIZE           64
+  #define CDC_TX_SIZE           64
+  #define MIDI_INTERFACE        2	// MIDI
+  #define MIDI_TX_ENDPOINT      3
+  #define MIDI_TX_SIZE          64
+  #define MIDI_RX_ENDPOINT      3
+  #define MIDI_RX_SIZE          64
+  #define KEYBOARD_INTERFACE    3	// Keyboard
+  #define KEYBOARD_ENDPOINT     4
+  #define KEYBOARD_SIZE         8
+  #define KEYBOARD_INTERVAL     1
+  #define MOUSE_INTERFACE       4	// Mouse
+  #define MOUSE_ENDPOINT        5
+  #define MOUSE_SIZE            8
+  #define MOUSE_INTERVAL        2
+  #define RAWHID_INTERFACE      5	// RawHID
+  #define RAWHID_TX_ENDPOINT    6
+  #define RAWHID_TX_SIZE        64
+  #define RAWHID_TX_INTERVAL    1
+  #define RAWHID_RX_ENDPOINT    6
+  #define RAWHID_RX_SIZE        64
+  #define RAWHID_RX_INTERVAL    1
+  #define FLIGHTSIM_INTERFACE	6	// Flight Sim Control
+  #define FLIGHTSIM_TX_ENDPOINT	9
+  #define FLIGHTSIM_TX_SIZE	64
+  #define FLIGHTSIM_TX_INTERVAL	1
+  #define FLIGHTSIM_RX_ENDPOINT	9
+  #define FLIGHTSIM_RX_SIZE	64
+  #define FLIGHTSIM_RX_INTERVAL	1
+  #define JOYSTICK_INTERFACE    7	// Joystick
+  #define JOYSTICK_ENDPOINT     10
+  #define JOYSTICK_SIZE         12	//  12 = normal, 64 = extreme joystick
+  #define JOYSTICK_INTERVAL     1
+/*
+  #define MTP_INTERFACE		8	// MTP Disk
+  #define MTP_TX_ENDPOINT	11
+  #define MTP_TX_SIZE		64
+  #define MTP_RX_ENDPOINT	3
+  #define MTP_RX_SIZE		64
+  #define MTP_EVENT_ENDPOINT	11
+  #define MTP_EVENT_SIZE	16
+  #define MTP_EVENT_INTERVAL	10
+*/
+  #define KEYMEDIA_INTERFACE    8	// Keyboard Media Keys
+  #define KEYMEDIA_ENDPOINT     12
+  #define KEYMEDIA_SIZE         8
+  #define KEYMEDIA_INTERVAL     4
+  #define AUDIO_INTERFACE	9	// Audio (uses 3 consecutive interfaces)
+  #define AUDIO_TX_ENDPOINT     13
+  #define AUDIO_TX_SIZE         180
+  #define AUDIO_RX_ENDPOINT     13
+  #define AUDIO_RX_SIZE         180
+  #define AUDIO_SYNC_ENDPOINT	14
+  #define MULTITOUCH_INTERFACE  12	// Touchscreen
+  #define MULTITOUCH_ENDPOINT   15
+  #define MULTITOUCH_SIZE       9
+  #define MULTITOUCH_FINGERS    10
+  #define ENDPOINT1_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT2_CONFIG	ENDPOINT_TRANSMIT_AND_RECEIVE
+  #define ENDPOINT3_CONFIG	ENDPOINT_TRANSMIT_AND_RECEIVE
+  #define ENDPOINT4_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT5_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT6_CONFIG	ENDPOINT_TRANSMIT_AND_RECEIVE
+  #define ENDPOINT7_CONFIG	ENDPOINT_TRANSMIT_AND_RECEIVE
+  #define ENDPOINT8_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT9_CONFIG	ENDPOINT_TRANSMIT_AND_RECEIVE
+  #define ENDPOINT10_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT11_CONFIG	ENDPOINT_TRANSMIT_AND_RECEIVE
+  #define ENDPOINT12_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+  #define ENDPOINT13_CONFIG	(ENDPOINT_RECEIVE_ISOCHRONOUS|ENDPOINT_TRANSMIT_ISOCHRONOUS)
+  #define ENDPOINT14_CONFIG	ENDPOINT_TRANSMIT_ISOCHRONOUS
+  #define ENDPOINT15_CONFIG	ENDPOINT_TRANSIMIT_ONLY
+
+#endif
+
+#ifdef USB_DESC_LIST_DEFINE
+#if defined(NUM_ENDPOINTS) && NUM_ENDPOINTS > 0
+// NUM_ENDPOINTS = number of non-zero endpoints (0 to 15)
+extern const uint8_t usb_endpoint_config_table[NUM_ENDPOINTS];
+
+typedef struct {
+	uint16_t	wValue;
+	uint16_t	wIndex;
+	const uint8_t	*addr;
+	uint16_t	length;
+} usb_descriptor_list_t;
+
+extern const usb_descriptor_list_t usb_descriptor_list[];
+#endif // NUM_ENDPOINTS
+#endif // USB_DESC_LIST_DEFINE
+
+#endif
diff --git a/motors/usb/usb_dev.c b/motors/usb/usb_dev.c
new file mode 100644
index 0000000..d57ca5d
--- /dev/null
+++ b/motors/usb/usb_dev.c
@@ -0,0 +1,1164 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Trying to understand this rather complex code?
+ *
+ * Kevin Cuzner wrote a simpler version, and a great blog article:
+ *   http://kevincuzner.com/2014/12/12/teensy-3-1-bare-metal-writing-a-usb-driver/
+ *   https://github.com/kcuzner/teensy-oscilloscope/blob/master/scope-teensy/src/usb.c
+ *
+ * Andy Payne wrote another relatively simple USB example for Freescale Kinetis
+ *   https://github.com/payne92/bare-metal-arm
+ */
+
+#include "usb_dev.h"
+#if F_CPU >= 20000000 && defined(NUM_ENDPOINTS)
+
+#include "kinetis.h"
+//#include "HardwareSerial.h"
+#include "usb_mem.h"
+#include <string.h> // for memset
+
+// buffer descriptor table
+
+typedef struct {
+	uint32_t desc;
+	void * addr;
+} bdt_t;
+
+__attribute__ ((section(".usbdescriptortable"), used))
+static bdt_t table[(NUM_ENDPOINTS+1)*4];
+
+static usb_packet_t *rx_first[NUM_ENDPOINTS];
+static usb_packet_t *rx_last[NUM_ENDPOINTS];
+static usb_packet_t *tx_first[NUM_ENDPOINTS];
+static usb_packet_t *tx_last[NUM_ENDPOINTS];
+uint16_t usb_rx_byte_count_data[NUM_ENDPOINTS];
+
+static uint8_t tx_state[NUM_ENDPOINTS];
+#define TX_STATE_BOTH_FREE_EVEN_FIRST	0
+#define TX_STATE_BOTH_FREE_ODD_FIRST	1
+#define TX_STATE_EVEN_FREE		2
+#define TX_STATE_ODD_FREE		3
+#define TX_STATE_NONE_FREE_EVEN_FIRST	4
+#define TX_STATE_NONE_FREE_ODD_FIRST	5
+
+#define BDT_OWN		0x80
+#define BDT_DATA1	0x40
+#define BDT_DATA0	0x00
+#define BDT_DTS		0x08
+#define BDT_STALL	0x04
+#define BDT_PID(n)	(((n) >> 2) & 15)
+
+#define BDT_DESC(count, data)	(BDT_OWN | BDT_DTS \
+				| ((data) ? BDT_DATA1 : BDT_DATA0) \
+				| ((count) << 16))
+
+#define TX   1
+#define RX   0
+#define ODD  1
+#define EVEN 0
+#define DATA0 0
+#define DATA1 1
+#define index(endpoint, tx, odd) (((endpoint) << 2) | ((tx) << 1) | (odd))
+#define stat2bufferdescriptor(stat) (table + ((stat) >> 2))
+
+
+static union {
+ struct {
+  union {
+   struct {
+	uint8_t bmRequestType;
+	uint8_t bRequest;
+   };
+	uint16_t wRequestAndType;
+  };
+	uint16_t wValue;
+	uint16_t wIndex;
+	uint16_t wLength;
+ };
+ struct {
+	uint32_t word1;
+	uint32_t word2;
+ };
+} setup;
+
+
+#define GET_STATUS		0
+#define CLEAR_FEATURE		1
+#define SET_FEATURE		3
+#define SET_ADDRESS		5
+#define GET_DESCRIPTOR		6
+#define SET_DESCRIPTOR		7
+#define GET_CONFIGURATION	8
+#define SET_CONFIGURATION	9
+#define GET_INTERFACE		10
+#define SET_INTERFACE		11
+#define SYNCH_FRAME		12
+
+// SETUP always uses a DATA0 PID for the data field of the SETUP transaction.
+// transactions in the data phase start with DATA1 and toggle (figure 8-12, USB1.1)
+// Status stage uses a DATA1 PID.
+
+static uint8_t ep0_rx0_buf[EP0_SIZE] __attribute__ ((aligned (4)));
+static uint8_t ep0_rx1_buf[EP0_SIZE] __attribute__ ((aligned (4)));
+static const uint8_t *ep0_tx_ptr = NULL;
+static uint16_t ep0_tx_len;
+static uint8_t ep0_tx_bdt_bank = 0;
+static uint8_t ep0_tx_data_toggle = 0;
+uint8_t usb_rx_memory_needed = 0;
+
+volatile uint8_t usb_configuration = 0;
+volatile uint8_t usb_reboot_timer = 0;
+
+
+static void endpoint0_stall(void)
+{
+	USB0_ENDPT0 = USB_ENDPT_EPSTALL | USB_ENDPT_EPRXEN | USB_ENDPT_EPTXEN | USB_ENDPT_EPHSHK;
+}
+
+
+static void endpoint0_transmit(const void *data, uint32_t len)
+{
+#if 0
+	serial_print("tx0:");
+	serial_phex32((uint32_t)data);
+	serial_print(",");
+	serial_phex16(len);
+	serial_print(ep0_tx_bdt_bank ? ", odd" : ", even");
+	serial_print(ep0_tx_data_toggle ? ", d1\n" : ", d0\n");
+#endif
+	table[index(0, TX, ep0_tx_bdt_bank)].addr = (void *)data;
+	table[index(0, TX, ep0_tx_bdt_bank)].desc = BDT_DESC(len, ep0_tx_data_toggle);
+	ep0_tx_data_toggle ^= 1;
+	ep0_tx_bdt_bank ^= 1;
+}
+
+static uint8_t reply_buffer[8];
+
+static void usb_setup(void)
+{
+	const uint8_t *data = NULL;
+	uint32_t datalen = 0;
+	const usb_descriptor_list_t *list;
+	uint32_t size;
+	volatile uint8_t *reg;
+	uint8_t epconf;
+	const uint8_t *cfg;
+	int i;
+
+	switch (setup.wRequestAndType) {
+	  case 0x0500: // SET_ADDRESS
+		break;
+	  case 0x0900: // SET_CONFIGURATION
+		//serial_print("configure\n");
+		usb_configuration = setup.wValue;
+		reg = &USB0_ENDPT1;
+		cfg = usb_endpoint_config_table;
+		// clear all BDT entries, free any allocated memory...
+		for (i=4; i < (NUM_ENDPOINTS+1)*4; i++) {
+			if (table[i].desc & BDT_OWN) {
+				usb_free((usb_packet_t *)((uint8_t *)(table[i].addr) - 8));
+			}
+		}
+		// free all queued packets
+		for (i=0; i < NUM_ENDPOINTS; i++) {
+			usb_packet_t *p, *n;
+			p = rx_first[i];
+			while (p) {
+				n = p->next;
+				usb_free(p);
+				p = n;
+			}
+			rx_first[i] = NULL;
+			rx_last[i] = NULL;
+			p = tx_first[i];
+			while (p) {
+				n = p->next;
+				usb_free(p);
+				p = n;
+			}
+			tx_first[i] = NULL;
+			tx_last[i] = NULL;
+			usb_rx_byte_count_data[i] = 0;
+			switch (tx_state[i]) {
+			  case TX_STATE_EVEN_FREE:
+			  case TX_STATE_NONE_FREE_EVEN_FIRST:
+				tx_state[i] = TX_STATE_BOTH_FREE_EVEN_FIRST;
+				break;
+			  case TX_STATE_ODD_FREE:
+			  case TX_STATE_NONE_FREE_ODD_FIRST:
+				tx_state[i] = TX_STATE_BOTH_FREE_ODD_FIRST;
+				break;
+			  default:
+				break;
+			}
+		}
+		usb_rx_memory_needed = 0;
+		for (i=1; i <= NUM_ENDPOINTS; i++) {
+			epconf = *cfg++;
+			*reg = epconf;
+			reg += 4;
+#ifdef AUDIO_INTERFACE
+			if (i == AUDIO_RX_ENDPOINT) {
+				table[index(i, RX, EVEN)].addr = usb_audio_receive_buffer;
+				table[index(i, RX, EVEN)].desc = (AUDIO_RX_SIZE<<16) | BDT_OWN;
+				table[index(i, RX, ODD)].addr = usb_audio_receive_buffer;
+				table[index(i, RX, ODD)].desc = (AUDIO_RX_SIZE<<16) | BDT_OWN;
+			} else
+#endif
+			if (epconf & USB_ENDPT_EPRXEN) {
+				usb_packet_t *p;
+				p = usb_malloc();
+				if (p) {
+					table[index(i, RX, EVEN)].addr = p->buf;
+					table[index(i, RX, EVEN)].desc = BDT_DESC(64, 0);
+				} else {
+					table[index(i, RX, EVEN)].desc = 0;
+					usb_rx_memory_needed++;
+				}
+				p = usb_malloc();
+				if (p) {
+					table[index(i, RX, ODD)].addr = p->buf;
+					table[index(i, RX, ODD)].desc = BDT_DESC(64, 1);
+				} else {
+					table[index(i, RX, ODD)].desc = 0;
+					usb_rx_memory_needed++;
+				}
+			}
+			table[index(i, TX, EVEN)].desc = 0;
+			table[index(i, TX, ODD)].desc = 0;
+#ifdef AUDIO_INTERFACE
+			if (i == AUDIO_SYNC_ENDPOINT) {
+				table[index(i, TX, EVEN)].addr = &usb_audio_sync_feedback;
+				table[index(i, TX, EVEN)].desc = (3<<16) | BDT_OWN;
+			}
+#endif
+		}
+		break;
+	  case 0x0880: // GET_CONFIGURATION
+		reply_buffer[0] = usb_configuration;
+		datalen = 1;
+		data = reply_buffer;
+		break;
+	  case 0x0080: // GET_STATUS (device)
+		reply_buffer[0] = 0;
+		reply_buffer[1] = 0;
+		datalen = 2;
+		data = reply_buffer;
+		break;
+	  case 0x0082: // GET_STATUS (endpoint)
+		i = setup.wIndex & 0x7F;
+		if (i > NUM_ENDPOINTS) {
+			// TODO: do we need to handle IN vs OUT here?
+			endpoint0_stall();
+			return;
+		}
+		reply_buffer[0] = 0;
+		reply_buffer[1] = 0;
+		if (*(uint8_t *)(&USB0_ENDPT0 + i * 4) & 0x02) reply_buffer[0] = 1;
+		data = reply_buffer;
+		datalen = 2;
+		break;
+	  case 0x0102: // CLEAR_FEATURE (endpoint)
+		i = setup.wIndex & 0x7F;
+		if (i > NUM_ENDPOINTS || setup.wValue != 0) {
+			// TODO: do we need to handle IN vs OUT here?
+			endpoint0_stall();
+			return;
+		}
+		(*(uint8_t *)(&USB0_ENDPT0 + i * 4)) &= ~0x02;
+		// TODO: do we need to clear the data toggle here?
+		break;
+	  case 0x0302: // SET_FEATURE (endpoint)
+		i = setup.wIndex & 0x7F;
+		if (i > NUM_ENDPOINTS || setup.wValue != 0) {
+			// TODO: do we need to handle IN vs OUT here?
+			endpoint0_stall();
+			return;
+		}
+		(*(uint8_t *)(&USB0_ENDPT0 + i * 4)) |= 0x02;
+		// TODO: do we need to clear the data toggle here?
+		break;
+	  case 0x0680: // GET_DESCRIPTOR
+	  case 0x0681:
+		//serial_print("desc:");
+		//serial_phex16(setup.wValue);
+		//serial_print("\n");
+		for (list = usb_descriptor_list; 1; list++) {
+			if (list->addr == NULL) break;
+			//if (setup.wValue == list->wValue &&
+			//(setup.wIndex == list->wIndex) || ((setup.wValue >> 8) == 3)) {
+			if (setup.wValue == list->wValue && setup.wIndex == list->wIndex) {
+				data = list->addr;
+				if ((setup.wValue >> 8) == 3) {
+					// for string descriptors, use the descriptor's
+					// length field, allowing runtime configured
+					// length.
+					datalen = *(list->addr);
+				} else {
+					datalen = list->length;
+				}
+#if 0
+				serial_print("Desc found, ");
+				serial_phex32((uint32_t)data);
+				serial_print(",");
+				serial_phex16(datalen);
+				serial_print(",");
+				serial_phex(data[0]);
+				serial_phex(data[1]);
+				serial_phex(data[2]);
+				serial_phex(data[3]);
+				serial_phex(data[4]);
+				serial_phex(data[5]);
+				serial_print("\n");
+#endif
+				goto send;
+			}
+		}
+		//serial_print("desc: not found\n");
+		endpoint0_stall();
+		return;
+#if defined(CDC_STATUS_INTERFACE)
+	  case 0x2221: // CDC_SET_CONTROL_LINE_STATE
+		usb_cdc_line_rtsdtr_millis = systick_millis_count;
+		usb_cdc_line_rtsdtr = setup.wValue;
+		//serial_print("set control line state\n");
+		break;
+	  case 0x2321: // CDC_SEND_BREAK
+		break;
+	  case 0x2021: // CDC_SET_LINE_CODING
+		//serial_print("set coding, waiting...\n");
+		return;
+#endif
+
+#if defined(MTP_INTERFACE)
+	case 0x64A1: // Cancel Request (PTP spec, 5.2.1, page 8)
+		// TODO: required by PTP spec
+		endpoint0_stall();
+		return;
+	case 0x66A1: // Device Reset (PTP spec, 5.2.3, page 10)
+		// TODO: required by PTP spec
+		endpoint0_stall();
+		return;
+	case 0x67A1: // Get Device Statis (PTP spec, 5.2.4, page 10)
+		// For now, always respond with status ok.
+		reply_buffer[0] = 0x4;
+		reply_buffer[1] = 0;
+		reply_buffer[2] = 0x01;
+		reply_buffer[3] = 0x20;
+		data = reply_buffer;
+		datalen = 4;
+		break;
+#endif
+
+// TODO: this does not work... why?
+#if defined(SEREMU_INTERFACE) || defined(KEYBOARD_INTERFACE)
+	  case 0x0921: // HID SET_REPORT
+		//serial_print(":)\n");
+		return;
+	  case 0x0A21: // HID SET_IDLE
+		break;
+	  // case 0xC940:
+#endif
+
+#if defined(AUDIO_INTERFACE)
+	  case 0x0B01: // SET_INTERFACE (alternate setting)
+		if (setup.wIndex == AUDIO_INTERFACE+1) {
+			usb_audio_transmit_setting = setup.wValue;
+			if (usb_audio_transmit_setting > 0) {
+				bdt_t *b = &table[index(AUDIO_TX_ENDPOINT, TX, EVEN)];
+				uint8_t state = tx_state[AUDIO_TX_ENDPOINT-1];
+				if (state) b++;
+				if (!(b->desc & BDT_OWN)) {
+					memset(usb_audio_transmit_buffer, 0, 176);
+					b->addr = usb_audio_transmit_buffer;
+					b->desc = (176 << 16) | BDT_OWN;
+					tx_state[AUDIO_TX_ENDPOINT-1] = state ^ 1;
+				}
+			}
+		} else if (setup.wIndex == AUDIO_INTERFACE+2) {
+			usb_audio_receive_setting = setup.wValue;
+		} else {
+			endpoint0_stall();
+			return;
+		}
+		break;
+	  case 0x0A81: // GET_INTERFACE (alternate setting)
+		datalen = 1;
+		data = reply_buffer;
+		if (setup.wIndex == AUDIO_INTERFACE+1) {
+			reply_buffer[0] = usb_audio_transmit_setting;
+		} else if (setup.wIndex == AUDIO_INTERFACE+2) {
+			reply_buffer[0] = usb_audio_receive_setting;
+		} else {
+			endpoint0_stall();
+			return;
+		}
+		break;
+	  case 0x0121: // SET FEATURE
+	  case 0x0221:
+	  case 0x0321:
+	  case 0x0421:
+	  	// handle these on the next packet. See usb_audio_set_feature()
+		return;
+	  case 0x81A1: // GET FEATURE
+	  case 0x82A1:
+	  case 0x83A1:
+	  case 0x84A1:
+	  	if (usb_audio_get_feature(&setup, reply_buffer, &datalen)) {
+	  		data = reply_buffer;
+	  	}
+	  	else {
+	  		endpoint0_stall();
+	  		return;
+	  	}
+		break;
+
+	  case 0x81A2: // GET_CUR (wValue=0, wIndex=interface, wLength=len)
+		if (setup.wLength >= 3) {
+			reply_buffer[0] = 44100 & 255;
+			reply_buffer[1] = 44100 >> 8;
+			reply_buffer[2] = 0;
+			datalen = 3;
+			data = reply_buffer;
+		} else {
+			endpoint0_stall();
+			return;
+		}
+		break;
+#endif
+
+#if defined(MULTITOUCH_INTERFACE)
+	  case 0x01A1:
+		if (setup.wValue == 0x0300 && setup.wIndex == MULTITOUCH_INTERFACE) {
+			reply_buffer[0] = MULTITOUCH_FINGERS;
+			data = reply_buffer;
+			datalen = 1;
+		} else {
+			endpoint0_stall();
+			return;
+		}
+		break;
+#endif
+	  default:
+		endpoint0_stall();
+		return;
+	}
+	send:
+	//serial_print("setup send ");
+	//serial_phex32(data);
+	//serial_print(",");
+	//serial_phex16(datalen);
+	//serial_print("\n");
+
+	if (datalen > setup.wLength) datalen = setup.wLength;
+	size = datalen;
+	if (size > EP0_SIZE) size = EP0_SIZE;
+	endpoint0_transmit(data, size);
+	data += size;
+	datalen -= size;
+	if (datalen == 0 && size < EP0_SIZE) return;
+
+	size = datalen;
+	if (size > EP0_SIZE) size = EP0_SIZE;
+	endpoint0_transmit(data, size);
+	data += size;
+	datalen -= size;
+	if (datalen == 0 && size < EP0_SIZE) return;
+
+	ep0_tx_ptr = data;
+	ep0_tx_len = datalen;
+}
+
+
+
+//A bulk endpoint's toggle sequence is initialized to DATA0 when the endpoint
+//experiences any configuration event (configuration events are explained in
+//Sections 9.1.1.5 and 9.4.5).
+
+//Configuring a device or changing an alternate setting causes all of the status
+//and configuration values associated with endpoints in the affected interfaces
+//to be set to their default values. This includes setting the data toggle of
+//any endpoint using data toggles to the value DATA0.
+
+//For endpoints using data toggle, regardless of whether an endpoint has the
+//Halt feature set, a ClearFeature(ENDPOINT_HALT) request always results in the
+//data toggle being reinitialized to DATA0.
+
+
+
+// #define stat2bufferdescriptor(stat) (table + ((stat) >> 2))
+
+static void usb_control(uint32_t stat)
+{
+	bdt_t *b;
+	uint32_t pid, size;
+	uint8_t *buf;
+	const uint8_t *data;
+
+	b = stat2bufferdescriptor(stat);
+	pid = BDT_PID(b->desc);
+	//count = b->desc >> 16;
+	buf = b->addr;
+	//serial_print("pid:");
+	//serial_phex(pid);
+	//serial_print(", count:");
+	//serial_phex(count);
+	//serial_print("\n");
+
+	switch (pid) {
+	case 0x0D: // Setup received from host
+		//serial_print("PID=Setup\n");
+		//if (count != 8) ; // panic?
+		// grab the 8 byte setup info
+		setup.word1 = *(uint32_t *)(buf);
+		setup.word2 = *(uint32_t *)(buf + 4);
+
+		// give the buffer back
+		b->desc = BDT_DESC(EP0_SIZE, DATA1);
+		//table[index(0, RX, EVEN)].desc = BDT_DESC(EP0_SIZE, 1);
+		//table[index(0, RX, ODD)].desc = BDT_DESC(EP0_SIZE, 1);
+
+		// clear any leftover pending IN transactions
+		ep0_tx_ptr = NULL;
+		if (ep0_tx_data_toggle) {
+		}
+		//if (table[index(0, TX, EVEN)].desc & 0x80) {
+			//serial_print("leftover tx even\n");
+		//}
+		//if (table[index(0, TX, ODD)].desc & 0x80) {
+			//serial_print("leftover tx odd\n");
+		//}
+		table[index(0, TX, EVEN)].desc = 0;
+		table[index(0, TX, ODD)].desc = 0;
+		// first IN after Setup is always DATA1
+		ep0_tx_data_toggle = 1;
+
+#if 0
+		serial_print("bmRequestType:");
+		serial_phex(setup.bmRequestType);
+		serial_print(", bRequest:");
+		serial_phex(setup.bRequest);
+		serial_print(", wValue:");
+		serial_phex16(setup.wValue);
+		serial_print(", wIndex:");
+		serial_phex16(setup.wIndex);
+		serial_print(", len:");
+		serial_phex16(setup.wLength);
+		serial_print("\n");
+#endif
+		// actually "do" the setup request
+		usb_setup();
+		// unfreeze the USB, now that we're ready
+		USB0_CTL = USB_CTL_USBENSOFEN; // clear TXSUSPENDTOKENBUSY bit
+		break;
+	case 0x01:  // OUT transaction received from host
+	case 0x02:
+		//serial_print("PID=OUT\n");
+#ifdef CDC_STATUS_INTERFACE
+		if (setup.wRequestAndType == 0x2021 /*CDC_SET_LINE_CODING*/) {
+			int i;
+			uint8_t *dst = (uint8_t *)usb_cdc_line_coding;
+			//serial_print("set line coding ");
+			for (i=0; i<7; i++) {
+				//serial_phex(*buf);
+				*dst++ = *buf++;
+			}
+			//serial_phex32(usb_cdc_line_coding[0]);
+			//serial_print("\n");
+			if (usb_cdc_line_coding[0] == 134) usb_reboot_timer = 15;
+			endpoint0_transmit(NULL, 0);
+		}
+#endif
+#ifdef KEYBOARD_INTERFACE
+		if (setup.word1 == 0x02000921 && setup.word2 == ((1<<16)|KEYBOARD_INTERFACE)) {
+			keyboard_leds = buf[0];
+			endpoint0_transmit(NULL, 0);
+		}
+#endif
+#ifdef SEREMU_INTERFACE
+		if (setup.word1 == 0x03000921 && setup.word2 == ((4<<16)|SEREMU_INTERFACE)
+		  && buf[0] == 0xA9 && buf[1] == 0x45 && buf[2] == 0xC2 && buf[3] == 0x6B) {
+			usb_reboot_timer = 5;
+			endpoint0_transmit(NULL, 0);
+		}
+#endif
+#ifdef AUDIO_INTERFACE
+		if (usb_audio_set_feature(&setup, buf)) {
+			endpoint0_transmit(NULL, 0);
+		}
+#endif
+		// give the buffer back
+		b->desc = BDT_DESC(EP0_SIZE, DATA1);
+		break;
+
+	case 0x09: // IN transaction completed to host
+		//serial_print("PID=IN:");
+		//serial_phex(stat);
+		//serial_print("\n");
+
+		// send remaining data, if any...
+		data = ep0_tx_ptr;
+		if (data) {
+			size = ep0_tx_len;
+			if (size > EP0_SIZE) size = EP0_SIZE;
+			endpoint0_transmit(data, size);
+			data += size;
+			ep0_tx_len -= size;
+			ep0_tx_ptr = (ep0_tx_len > 0 || size == EP0_SIZE) ? data : NULL;
+		}
+
+		if (setup.bRequest == 5 && setup.bmRequestType == 0) {
+			setup.bRequest = 0;
+			//serial_print("set address: ");
+			//serial_phex16(setup.wValue);
+			//serial_print("\n");
+			USB0_ADDR = setup.wValue;
+		}
+
+		break;
+	//default:
+		//serial_print("PID=unknown:");
+		//serial_phex(pid);
+		//serial_print("\n");
+	}
+	USB0_CTL = USB_CTL_USBENSOFEN; // clear TXSUSPENDTOKENBUSY bit
+}
+
+
+
+
+
+
+usb_packet_t *usb_rx(uint32_t endpoint)
+{
+	usb_packet_t *ret;
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return NULL;
+	__disable_irq();
+	ret = rx_first[endpoint];
+	if (ret) {
+		rx_first[endpoint] = ret->next;
+		usb_rx_byte_count_data[endpoint] -= ret->len;
+	}
+	__enable_irq();
+	//serial_print("rx, epidx=");
+	//serial_phex(endpoint);
+	//serial_print(", packet=");
+	//serial_phex32(ret);
+	//serial_print("\n");
+	return ret;
+}
+
+static uint32_t usb_queue_byte_count(const usb_packet_t *p)
+{
+	uint32_t count=0;
+
+	__disable_irq();
+	for ( ; p; p = p->next) {
+		count += p->len;
+	}
+	__enable_irq();
+	return count;
+}
+
+// TODO: make this an inline function...
+/*
+uint32_t usb_rx_byte_count(uint32_t endpoint)
+{
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return 0;
+	return usb_rx_byte_count_data[endpoint];
+	//return usb_queue_byte_count(rx_first[endpoint]);
+}
+*/
+
+uint32_t usb_tx_byte_count(uint32_t endpoint)
+{
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return 0;
+	return usb_queue_byte_count(tx_first[endpoint]);
+}
+
+uint32_t usb_tx_packet_count(uint32_t endpoint)
+{
+	const usb_packet_t *p;
+	uint32_t count=0;
+
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return 0;
+	__disable_irq();
+	for (p = tx_first[endpoint]; p; p = p->next) count++;
+	__enable_irq();
+	return count;
+}
+
+
+// Called from usb_free, but only when usb_rx_memory_needed > 0, indicating
+// receive endpoints are starving for memory.  The intention is to give
+// endpoints needing receive memory priority over the user's code, which is
+// likely calling usb_malloc to obtain memory for transmitting.  When the
+// user is creating data very quickly, their consumption could starve reception
+// without this prioritization.  The packet buffer (input) is assigned to the
+// first endpoint needing memory.
+//
+void usb_rx_memory(usb_packet_t *packet)
+{
+	unsigned int i;
+	const uint8_t *cfg;
+
+	cfg = usb_endpoint_config_table;
+	//serial_print("rx_mem:");
+	__disable_irq();
+	for (i=1; i <= NUM_ENDPOINTS; i++) {
+#ifdef AUDIO_INTERFACE
+		if (i == AUDIO_RX_ENDPOINT) continue;
+#endif
+		if (*cfg++ & USB_ENDPT_EPRXEN) {
+			if (table[index(i, RX, EVEN)].desc == 0) {
+				table[index(i, RX, EVEN)].addr = packet->buf;
+				table[index(i, RX, EVEN)].desc = BDT_DESC(64, 0);
+				usb_rx_memory_needed--;
+				__enable_irq();
+				//serial_phex(i);
+				//serial_print(",even\n");
+				return;
+			}
+			if (table[index(i, RX, ODD)].desc == 0) {
+				table[index(i, RX, ODD)].addr = packet->buf;
+				table[index(i, RX, ODD)].desc = BDT_DESC(64, 1);
+				usb_rx_memory_needed--;
+				__enable_irq();
+				//serial_phex(i);
+				//serial_print(",odd\n");
+				return;
+			}
+		}
+	}
+	__enable_irq();
+	// we should never reach this point.  If we get here, it means
+	// usb_rx_memory_needed was set greater than zero, but no memory
+	// was actually needed.
+	usb_rx_memory_needed = 0;
+	usb_free(packet);
+	return;
+}
+
+//#define index(endpoint, tx, odd) (((endpoint) << 2) | ((tx) << 1) | (odd))
+//#define stat2bufferdescriptor(stat) (table + ((stat) >> 2))
+
+void usb_tx(uint32_t endpoint, usb_packet_t *packet)
+{
+	bdt_t *b = &table[index(endpoint, TX, EVEN)];
+	uint8_t next;
+
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return;
+	__disable_irq();
+	//serial_print("txstate=");
+	//serial_phex(tx_state[endpoint]);
+	//serial_print("\n");
+	switch (tx_state[endpoint]) {
+	  case TX_STATE_BOTH_FREE_EVEN_FIRST:
+		next = TX_STATE_ODD_FREE;
+		break;
+	  case TX_STATE_BOTH_FREE_ODD_FIRST:
+		b++;
+		next = TX_STATE_EVEN_FREE;
+		break;
+	  case TX_STATE_EVEN_FREE:
+		next = TX_STATE_NONE_FREE_ODD_FIRST;
+		break;
+	  case TX_STATE_ODD_FREE:
+		b++;
+		next = TX_STATE_NONE_FREE_EVEN_FIRST;
+		break;
+	  default:
+		if (tx_first[endpoint] == NULL) {
+			tx_first[endpoint] = packet;
+		} else {
+			tx_last[endpoint]->next = packet;
+		}
+		tx_last[endpoint] = packet;
+		__enable_irq();
+		return;
+	}
+	tx_state[endpoint] = next;
+	b->addr = packet->buf;
+	b->desc = BDT_DESC(packet->len, ((uint32_t)b & 8) ? DATA1 : DATA0);
+	__enable_irq();
+}
+
+void usb_tx_isochronous(uint32_t endpoint, void *data, uint32_t len)
+{
+	bdt_t *b = &table[index(endpoint, TX, EVEN)];
+	uint8_t next, state;
+
+	endpoint--;
+	if (endpoint >= NUM_ENDPOINTS) return;
+	__disable_irq();
+	state = tx_state[endpoint];
+	if (state == 0) {
+		next = 1;
+	} else {
+		b++;
+		next = 0;
+	}
+	tx_state[endpoint] = next;
+	b->addr = data;
+	b->desc = (len << 16) | BDT_OWN;
+	__enable_irq();
+}
+
+
+
+
+void _reboot_Teensyduino_(void)
+{
+	// TODO: initialize R0 with a code....
+	__asm__ volatile("bkpt");
+}
+
+
+
+void usb_isr(void)
+{
+	uint8_t status, stat, t;
+
+	//serial_print("isr");
+	//status = USB0_ISTAT;
+	//serial_phex(status);
+	//serial_print("\n");
+	restart:
+	status = USB0_ISTAT;
+
+	if ((status & USB_ISTAT_SOFTOK /* 04 */ )) {
+		if (usb_configuration) {
+			t = usb_reboot_timer;
+			if (t) {
+				usb_reboot_timer = --t;
+				if (!t) _reboot_Teensyduino_();
+			}
+#ifdef CDC_DATA_INTERFACE
+			t = usb_cdc_transmit_flush_timer;
+			if (t) {
+				usb_cdc_transmit_flush_timer = --t;
+				if (t == 0) usb_serial_flush_callback();
+			}
+#endif
+#ifdef SEREMU_INTERFACE
+			t = usb_seremu_transmit_flush_timer;
+			if (t) {
+				usb_seremu_transmit_flush_timer = --t;
+				if (t == 0) usb_seremu_flush_callback();
+			}
+#endif
+#ifdef MIDI_INTERFACE
+                        usb_midi_flush_output();
+#endif
+#ifdef FLIGHTSIM_INTERFACE
+			usb_flightsim_flush_callback();
+#endif
+#ifdef MULTITOUCH_INTERFACE
+			usb_touchscreen_update_callback();
+#endif
+		}
+		USB0_ISTAT = USB_ISTAT_SOFTOK;
+	}
+
+	if ((status & USB_ISTAT_TOKDNE /* 08 */ )) {
+		uint8_t endpoint;
+		stat = USB0_STAT;
+		//serial_print("token: ep=");
+		//serial_phex(stat >> 4);
+		//serial_print(stat & 0x08 ? ",tx" : ",rx");
+		//serial_print(stat & 0x04 ? ",odd\n" : ",even\n");
+		endpoint = stat >> 4;
+		if (endpoint == 0) {
+			usb_control(stat);
+		} else {
+			bdt_t *b = stat2bufferdescriptor(stat);
+			usb_packet_t *packet = (usb_packet_t *)((uint8_t *)(b->addr) - 8);
+#if 0
+			serial_print("ep:");
+			serial_phex(endpoint);
+			serial_print(", pid:");
+			serial_phex(BDT_PID(b->desc));
+			serial_print(((uint32_t)b & 8) ? ", odd" : ", even");
+			serial_print(", count:");
+			serial_phex(b->desc >> 16);
+			serial_print("\n");
+#endif
+			endpoint--;	// endpoint is index to zero-based arrays
+
+#ifdef AUDIO_INTERFACE
+			if ((endpoint == AUDIO_TX_ENDPOINT-1) && (stat & 0x08)) {
+				unsigned int len;
+				len = usb_audio_transmit_callback();
+				if (len > 0) {
+					b = (bdt_t *)((uint32_t)b ^ 8);
+					b->addr = usb_audio_transmit_buffer;
+					b->desc = (len << 16) | BDT_OWN;
+					tx_state[endpoint] ^= 1;
+				}
+			} else if ((endpoint == AUDIO_RX_ENDPOINT-1) && !(stat & 0x08)) {
+				usb_audio_receive_callback(b->desc >> 16);
+				b->addr = usb_audio_receive_buffer;
+				b->desc = (AUDIO_RX_SIZE << 16) | BDT_OWN;
+			} else if ((endpoint == AUDIO_SYNC_ENDPOINT-1) && (stat & 0x08)) {
+				b = (bdt_t *)((uint32_t)b ^ 8);
+				b->addr = &usb_audio_sync_feedback;
+				b->desc = (3 << 16) | BDT_OWN;
+				tx_state[endpoint] ^= 1;
+			} else
+#endif
+			if (stat & 0x08) { // transmit
+				usb_free(packet);
+				packet = tx_first[endpoint];
+				if (packet) {
+					//serial_print("tx packet\n");
+					tx_first[endpoint] = packet->next;
+					b->addr = packet->buf;
+					switch (tx_state[endpoint]) {
+					  case TX_STATE_BOTH_FREE_EVEN_FIRST:
+						tx_state[endpoint] = TX_STATE_ODD_FREE;
+						break;
+					  case TX_STATE_BOTH_FREE_ODD_FIRST:
+						tx_state[endpoint] = TX_STATE_EVEN_FREE;
+						break;
+					  case TX_STATE_EVEN_FREE:
+						tx_state[endpoint] = TX_STATE_NONE_FREE_ODD_FIRST;
+						break;
+					  case TX_STATE_ODD_FREE:
+						tx_state[endpoint] = TX_STATE_NONE_FREE_EVEN_FIRST;
+						break;
+					  default:
+						break;
+					}
+					b->desc = BDT_DESC(packet->len,
+						((uint32_t)b & 8) ? DATA1 : DATA0);
+				} else {
+					//serial_print("tx no packet\n");
+					switch (tx_state[endpoint]) {
+					  case TX_STATE_BOTH_FREE_EVEN_FIRST:
+					  case TX_STATE_BOTH_FREE_ODD_FIRST:
+						break;
+					  case TX_STATE_EVEN_FREE:
+						tx_state[endpoint] = TX_STATE_BOTH_FREE_EVEN_FIRST;
+						break;
+					  case TX_STATE_ODD_FREE:
+						tx_state[endpoint] = TX_STATE_BOTH_FREE_ODD_FIRST;
+						break;
+					  default:
+						tx_state[endpoint] = ((uint32_t)b & 8) ?
+						  TX_STATE_ODD_FREE : TX_STATE_EVEN_FREE;
+						break;
+					}
+				}
+			} else { // receive
+				packet->len = b->desc >> 16;
+				if (packet->len > 0) {
+					packet->index = 0;
+					packet->next = NULL;
+					if (rx_first[endpoint] == NULL) {
+						//serial_print("rx 1st, epidx=");
+						//serial_phex(endpoint);
+						//serial_print(", packet=");
+						//serial_phex32((uint32_t)packet);
+						//serial_print("\n");
+						rx_first[endpoint] = packet;
+					} else {
+						//serial_print("rx Nth, epidx=");
+						//serial_phex(endpoint);
+						//serial_print(", packet=");
+						//serial_phex32((uint32_t)packet);
+						//serial_print("\n");
+						rx_last[endpoint]->next = packet;
+					}
+					rx_last[endpoint] = packet;
+					usb_rx_byte_count_data[endpoint] += packet->len;
+					// TODO: implement a per-endpoint maximum # of allocated
+					// packets, so a flood of incoming data on 1 endpoint
+					// doesn't starve the others if the user isn't reading
+					// it regularly
+					packet = usb_malloc();
+					if (packet) {
+						b->addr = packet->buf;
+						b->desc = BDT_DESC(64,
+							((uint32_t)b & 8) ? DATA1 : DATA0);
+					} else {
+						//serial_print("starving ");
+						//serial_phex(endpoint + 1);
+						b->desc = 0;
+						usb_rx_memory_needed++;
+					}
+				} else {
+					b->desc = BDT_DESC(64, ((uint32_t)b & 8) ? DATA1 : DATA0);
+				}
+			}
+
+		}
+		USB0_ISTAT = USB_ISTAT_TOKDNE;
+		goto restart;
+	}
+
+
+
+	if (status & USB_ISTAT_USBRST /* 01 */ ) {
+		//serial_print("reset\n");
+
+		// initialize BDT toggle bits
+		USB0_CTL = USB_CTL_ODDRST;
+		ep0_tx_bdt_bank = 0;
+
+		// set up buffers to receive Setup and OUT packets
+		table[index(0, RX, EVEN)].desc = BDT_DESC(EP0_SIZE, 0);
+		table[index(0, RX, EVEN)].addr = ep0_rx0_buf;
+		table[index(0, RX, ODD)].desc = BDT_DESC(EP0_SIZE, 0);
+		table[index(0, RX, ODD)].addr = ep0_rx1_buf;
+		table[index(0, TX, EVEN)].desc = 0;
+		table[index(0, TX, ODD)].desc = 0;
+
+		// activate endpoint 0
+		USB0_ENDPT0 = USB_ENDPT_EPRXEN | USB_ENDPT_EPTXEN | USB_ENDPT_EPHSHK;
+
+		// clear all ending interrupts
+		USB0_ERRSTAT = 0xFF;
+		USB0_ISTAT = 0xFF;
+
+		// set the address to zero during enumeration
+		USB0_ADDR = 0;
+
+		// enable other interrupts
+		USB0_ERREN = 0xFF;
+		USB0_INTEN = USB_INTEN_TOKDNEEN |
+			USB_INTEN_SOFTOKEN |
+			USB_INTEN_STALLEN |
+			USB_INTEN_ERROREN |
+			USB_INTEN_USBRSTEN |
+			USB_INTEN_SLEEPEN;
+
+		// is this necessary?
+		USB0_CTL = USB_CTL_USBENSOFEN;
+		return;
+	}
+
+
+	if ((status & USB_ISTAT_STALL /* 80 */ )) {
+		//serial_print("stall:\n");
+		USB0_ENDPT0 = USB_ENDPT_EPRXEN | USB_ENDPT_EPTXEN | USB_ENDPT_EPHSHK;
+		USB0_ISTAT = USB_ISTAT_STALL;
+	}
+	if ((status & USB_ISTAT_ERROR /* 02 */ )) {
+		uint8_t err = USB0_ERRSTAT;
+		USB0_ERRSTAT = err;
+		//serial_print("err:");
+		//serial_phex(err);
+		//serial_print("\n");
+		USB0_ISTAT = USB_ISTAT_ERROR;
+	}
+
+	if ((status & USB_ISTAT_SLEEP /* 10 */ )) {
+		//serial_print("sleep\n");
+		USB0_ISTAT = USB_ISTAT_SLEEP;
+	}
+
+}
+
+
+
+void usb_init(void)
+{
+	int i;
+
+	//serial_begin(BAUD2DIV(115200));
+	//serial_print("usb_init\n");
+
+	usb_init_serialnumber();
+
+	for (i=0; i <= NUM_ENDPOINTS*4; i++) {
+		table[i].desc = 0;
+		table[i].addr = 0;
+	}
+
+	// this basically follows the flowchart in the Kinetis
+	// Quick Reference User Guide, Rev. 1, 03/2012, page 141
+
+	// assume 48 MHz clock already running
+	// SIM - enable clock
+	SIM_SCGC4 |= SIM_SCGC4_USBOTG;
+#ifdef HAS_KINETIS_MPU
+	MPU_RGDAAC0 |= 0x03000000;
+#endif
+#if F_CPU == 180000000 || F_CPU == 216000000
+	// if using IRC48M, turn on the USB clock recovery hardware
+	USB0_CLK_RECOVER_IRC_EN = USB_CLK_RECOVER_IRC_EN_IRC_EN | USB_CLK_RECOVER_IRC_EN_REG_EN;
+	USB0_CLK_RECOVER_CTRL = USB_CLK_RECOVER_CTRL_CLOCK_RECOVER_EN |
+		USB_CLK_RECOVER_CTRL_RESTART_IFRTRIM_EN;
+#endif
+	// reset USB module
+	//USB0_USBTRC0 = USB_USBTRC_USBRESET;
+	//while ((USB0_USBTRC0 & USB_USBTRC_USBRESET) != 0) ; // wait for reset to end
+
+	// set desc table base addr
+	USB0_BDTPAGE1 = ((uint32_t)table) >> 8;
+	USB0_BDTPAGE2 = ((uint32_t)table) >> 16;
+	USB0_BDTPAGE3 = ((uint32_t)table) >> 24;
+
+	// clear all ISR flags
+	USB0_ISTAT = 0xFF;
+	USB0_ERRSTAT = 0xFF;
+	USB0_OTGISTAT = 0xFF;
+
+	//USB0_USBTRC0 |= 0x40; // undocumented bit
+
+	// enable USB
+	USB0_CTL = USB_CTL_USBENSOFEN;
+	USB0_USBCTRL = 0;
+
+	// enable reset interrupt
+	USB0_INTEN = USB_INTEN_USBRSTEN;
+
+	// enable interrupt in NVIC...
+	NVIC_SET_PRIORITY(IRQ_USBOTG, 112);
+	NVIC_ENABLE_IRQ(IRQ_USBOTG);
+
+	// enable d+ pullup
+	USB0_CONTROL = USB_CONTROL_DPPULLUPNONOTG;
+}
+
+
+#else // F_CPU < 20 MHz && defined(NUM_ENDPOINTS)
+
+void usb_init(void)
+{
+}
+
+#endif // F_CPU >= 20 MHz && defined(NUM_ENDPOINTS)
diff --git a/motors/usb/usb_dev.h b/motors/usb/usb_dev.h
new file mode 100644
index 0000000..1233d7f
--- /dev/null
+++ b/motors/usb/usb_dev.h
@@ -0,0 +1,137 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef _usb_dev_h_
+#define _usb_dev_h_
+
+#define USB_DESC_LIST_DEFINE
+#include "usb_desc.h"
+
+#if F_CPU >= 20000000 && !defined(USB_DISABLED)
+
+// This header is NOT meant to be included when compiling
+// user sketches in Arduino.  The low-level functions
+// provided by usb_dev.c are meant to be called only by
+// code which provides higher-level interfaces to the user.
+
+#include "usb_mem.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void usb_init(void);
+void usb_init_serialnumber(void);
+void usb_isr(void);
+usb_packet_t *usb_rx(uint32_t endpoint);
+uint32_t usb_tx_byte_count(uint32_t endpoint);
+uint32_t usb_tx_packet_count(uint32_t endpoint);
+void usb_tx(uint32_t endpoint, usb_packet_t *packet);
+void usb_tx_isochronous(uint32_t endpoint, void *data, uint32_t len);
+
+extern volatile uint8_t usb_configuration;
+
+extern uint16_t usb_rx_byte_count_data[NUM_ENDPOINTS];
+static inline uint32_t usb_rx_byte_count(uint32_t endpoint) __attribute__((always_inline));
+static inline uint32_t usb_rx_byte_count(uint32_t endpoint)
+{
+        endpoint--;
+        if (endpoint >= NUM_ENDPOINTS) return 0;
+        return usb_rx_byte_count_data[endpoint];
+}
+
+#ifdef CDC_DATA_INTERFACE
+extern uint32_t usb_cdc_line_coding[2];
+extern volatile uint32_t usb_cdc_line_rtsdtr_millis;
+extern volatile uint32_t systick_millis_count;
+extern volatile uint8_t usb_cdc_line_rtsdtr;
+extern volatile uint8_t usb_cdc_transmit_flush_timer;
+extern void usb_serial_flush_callback(void);
+#endif
+
+#ifdef SEREMU_INTERFACE
+extern volatile uint8_t usb_seremu_transmit_flush_timer;
+extern void usb_seremu_flush_callback(void);
+#endif
+
+#ifdef KEYBOARD_INTERFACE
+extern uint8_t keyboard_modifier_keys;
+extern uint8_t keyboard_keys[6];
+extern uint8_t keyboard_protocol;
+extern uint8_t keyboard_idle_config;
+extern uint8_t keyboard_idle_count;
+extern volatile uint8_t keyboard_leds;
+#endif
+
+#ifdef MIDI_INTERFACE
+extern void usb_midi_flush_output(void);
+#endif
+
+#ifdef FLIGHTSIM_INTERFACE
+extern void usb_flightsim_flush_callback(void);
+#endif
+
+#ifdef AUDIO_INTERFACE
+extern uint16_t usb_audio_receive_buffer[];
+extern uint16_t usb_audio_transmit_buffer[];
+extern uint32_t usb_audio_sync_feedback;
+extern uint8_t usb_audio_receive_setting;
+extern uint8_t usb_audio_transmit_setting;
+extern void usb_audio_receive_callback(unsigned int len);
+extern unsigned int usb_audio_transmit_callback(void);
+extern int usb_audio_get_feature(void *stp, uint8_t *data, uint32_t *datalen);
+extern int usb_audio_set_feature(void *stp, uint8_t *buf);
+#endif
+
+#ifdef MULTITOUCH_INTERFACE
+extern void usb_touchscreen_update_callback(void);
+#endif
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#else // F_CPU < 20000000
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void usb_init(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif // F_CPU
+
+#endif
diff --git a/motors/usb/usb_mem.c b/motors/usb/usb_mem.c
new file mode 100644
index 0000000..41b4596
--- /dev/null
+++ b/motors/usb/usb_mem.c
@@ -0,0 +1,109 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "usb_dev.h"
+#if F_CPU >= 20000000 && defined(NUM_ENDPOINTS)
+
+#include "kinetis.h"
+//#include "HardwareSerial.h"
+#include "usb_mem.h"
+
+__attribute__ ((section(".usbbuffers"), used))
+unsigned char usb_buffer_memory[NUM_USB_BUFFERS * sizeof(usb_packet_t)];
+
+static uint32_t usb_buffer_available = 0xFFFFFFFF;
+
+// use bitmask and CLZ instruction to implement fast free list
+// http://www.archivum.info/gnu.gcc.help/2006-08/00148/Re-GCC-Inline-Assembly.html
+// http://gcc.gnu.org/ml/gcc/2012-06/msg00015.html
+// __builtin_clz()
+
+usb_packet_t * usb_malloc(void)
+{
+	unsigned int n, avail;
+	uint8_t *p;
+
+	__disable_irq();
+	avail = usb_buffer_available;
+	n = __builtin_clz(avail); // clz = count leading zeros
+	if (n >= NUM_USB_BUFFERS) {
+		__enable_irq();
+		return NULL;
+	}
+	//serial_print("malloc:");
+	//serial_phex(n);
+	//serial_print("\n");
+
+	usb_buffer_available = avail & ~(0x80000000 >> n);
+	__enable_irq();
+	p = usb_buffer_memory + (n * sizeof(usb_packet_t));
+	//serial_print("malloc:");
+	//serial_phex32((int)p);
+	//serial_print("\n");
+	*(uint32_t *)p = 0;
+	*(uint32_t *)(p + 4) = 0;
+	return (usb_packet_t *)p;
+}
+
+// for the receive endpoints to request memory
+extern uint8_t usb_rx_memory_needed;
+extern void usb_rx_memory(usb_packet_t *packet);
+
+void usb_free(usb_packet_t *p)
+{
+	unsigned int n, mask;
+
+	//serial_print("free:");
+	n = ((uint8_t *)p - usb_buffer_memory) / sizeof(usb_packet_t);
+	if (n >= NUM_USB_BUFFERS) return;
+	//serial_phex(n);
+	//serial_print("\n");
+
+	// if any endpoints are starving for memory to receive
+	// packets, give this memory to them immediately!
+	if (usb_rx_memory_needed && usb_configuration) {
+		//serial_print("give to rx:");
+		//serial_phex32((int)p);
+		//serial_print("\n");
+		usb_rx_memory(p);
+		return;
+	}
+
+	mask = (0x80000000 >> n);
+	__disable_irq();
+	usb_buffer_available |= mask;
+	__enable_irq();
+
+	//serial_print("free:");
+	//serial_phex32((int)p);
+	//serial_print("\n");
+}
+
+#endif // F_CPU >= 20 MHz && defined(NUM_ENDPOINTS)
diff --git a/motors/usb/usb_mem.h b/motors/usb/usb_mem.h
new file mode 100644
index 0000000..8064488
--- /dev/null
+++ b/motors/usb/usb_mem.h
@@ -0,0 +1,55 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef _usb_mem_h_
+#define _usb_mem_h_
+
+#include <stdint.h>
+
+typedef struct usb_packet_struct {
+	uint16_t len;
+	uint16_t index;
+	struct usb_packet_struct *next;
+	uint8_t buf[64];
+} usb_packet_t;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+usb_packet_t * usb_malloc(void);
+void usb_free(usb_packet_t *p);
+
+#ifdef __cplusplus
+}
+#endif
+
+
+#endif
diff --git a/motors/usb/usb_names.h b/motors/usb/usb_names.h
new file mode 100644
index 0000000..1cd5fda
--- /dev/null
+++ b/motors/usb/usb_names.h
@@ -0,0 +1,57 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef _usb_names_h_
+#define _usb_names_h_
+
+// These definitions are intended to allow users to override the default
+// USB manufacturer, product and serial number strings.
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct usb_string_descriptor_struct {
+	uint8_t bLength;
+	uint8_t bDescriptorType;
+	uint16_t wString[];
+};
+
+extern struct usb_string_descriptor_struct usb_string_manufacturer_name;
+extern struct usb_string_descriptor_struct usb_string_product_name;
+extern struct usb_string_descriptor_struct usb_string_serial_number;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/motors/usb/usb_serial.c b/motors/usb/usb_serial.c
new file mode 100644
index 0000000..a312176
--- /dev/null
+++ b/motors/usb/usb_serial.c
@@ -0,0 +1,305 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "usb_dev.h"
+#include "usb_serial.h"
+#include "core_pins.h" // for yield()
+//#include "HardwareSerial.h"
+#include <string.h> // for memcpy()
+
+// defined by usb_dev.h -> usb_desc.h
+#if defined(CDC_STATUS_INTERFACE) && defined(CDC_DATA_INTERFACE)
+#if F_CPU >= 20000000
+
+uint32_t usb_cdc_line_coding[2];
+volatile uint32_t usb_cdc_line_rtsdtr_millis;
+volatile uint8_t usb_cdc_line_rtsdtr=0;
+volatile uint8_t usb_cdc_transmit_flush_timer=0;
+
+static usb_packet_t *rx_packet=NULL;
+static usb_packet_t *tx_packet=NULL;
+static volatile uint8_t tx_noautoflush=0;
+
+#define TRANSMIT_FLUSH_TIMEOUT	5   /* in milliseconds */
+
+// get the next character, or -1 if nothing received
+int usb_serial_getchar(void)
+{
+	unsigned int i;
+	int c;
+
+	if (!rx_packet) {
+		if (!usb_configuration) return -1;
+		rx_packet = usb_rx(CDC_RX_ENDPOINT);
+		if (!rx_packet) return -1;
+	}
+	i = rx_packet->index;
+	c = rx_packet->buf[i++];
+	if (i >= rx_packet->len) {
+		usb_free(rx_packet);
+		rx_packet = NULL;
+	} else {
+		rx_packet->index = i;
+	}
+	return c;
+}
+
+// peek at the next character, or -1 if nothing received
+int usb_serial_peekchar(void)
+{
+	if (!rx_packet) {
+		if (!usb_configuration) return -1;
+		rx_packet = usb_rx(CDC_RX_ENDPOINT);
+		if (!rx_packet) return -1;
+	}
+	if (!rx_packet) return -1;
+	return rx_packet->buf[rx_packet->index];
+}
+
+// number of bytes available in the receive buffer
+int usb_serial_available(void)
+{
+	int count;
+	count = usb_rx_byte_count(CDC_RX_ENDPOINT);
+	if (rx_packet) count += rx_packet->len - rx_packet->index;
+	return count;
+}
+
+// read a block of bytes to a buffer
+int usb_serial_read(void *buffer, uint32_t size)
+{
+	uint8_t *p = (uint8_t *)buffer;
+	uint32_t qty, count=0;
+
+	while (size) {
+		if (!usb_configuration) break;
+		if (!rx_packet) {
+			rx:
+			rx_packet = usb_rx(CDC_RX_ENDPOINT);
+			if (!rx_packet) break;
+			if (rx_packet->len == 0) {
+				usb_free(rx_packet);
+				goto rx;
+			}
+		}
+		qty = rx_packet->len - rx_packet->index;
+		if (qty > size) qty = size;
+		memcpy(p, rx_packet->buf + rx_packet->index, qty);
+		p += qty;
+		count += qty;
+		size -= qty;
+		rx_packet->index += qty;
+		if (rx_packet->index >= rx_packet->len) {
+			usb_free(rx_packet);
+			rx_packet = NULL;
+		}
+	}
+	return count;
+}
+
+// discard any buffered input
+void usb_serial_flush_input(void)
+{
+	usb_packet_t *rx;
+
+	if (!usb_configuration) return;
+	if (rx_packet) {
+		usb_free(rx_packet);
+		rx_packet = NULL;
+	}
+	while (1) {
+		rx = usb_rx(CDC_RX_ENDPOINT);
+		if (!rx) break;
+		usb_free(rx);
+	}
+}
+
+// Maximum number of transmit packets to queue so we don't starve other endpoints for memory
+#define TX_PACKET_LIMIT 8
+
+// When the PC isn't listening, how long do we wait before discarding data?  If this is
+// too short, we risk losing data during the stalls that are common with ordinary desktop
+// software.  If it's too long, we stall the user's program when no software is running.
+#define TX_TIMEOUT_MSEC 70
+
+#if F_CPU == 240000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 1600)
+#elif F_CPU == 216000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 1440)
+#elif F_CPU == 192000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 1280)
+#elif F_CPU == 180000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 1200)
+#elif F_CPU == 168000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 1100)
+#elif F_CPU == 144000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 932)
+#elif F_CPU == 120000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 764)
+#elif F_CPU == 96000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 596)
+#elif F_CPU == 72000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 512)
+#elif F_CPU == 48000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 428)
+#elif F_CPU == 24000000
+  #define TX_TIMEOUT (TX_TIMEOUT_MSEC * 262)
+#endif
+
+// When we've suffered the transmit timeout, don't wait again until the computer
+// begins accepting data.  If no software is running to receive, we'll just discard
+// data as rapidly as Serial.print() can generate it, until there's something to
+// actually receive it.
+static uint8_t transmit_previous_timeout=0;
+
+
+// transmit a character.  0 returned on success, -1 on error
+int usb_serial_putchar(uint8_t c)
+{
+	return usb_serial_write(&c, 1);
+}
+
+
+int usb_serial_write(const void *buffer, uint32_t size)
+{
+	uint32_t ret = size;
+	uint32_t len;
+	uint32_t wait_count;
+	const uint8_t *src = (const uint8_t *)buffer;
+	uint8_t *dest;
+
+	tx_noautoflush = 1;
+	while (size > 0) {
+		if (!tx_packet) {
+			wait_count = 0;
+			while (1) {
+				if (!usb_configuration) {
+					tx_noautoflush = 0;
+					return -1;
+				}
+				if (usb_tx_packet_count(CDC_TX_ENDPOINT) < TX_PACKET_LIMIT) {
+					tx_noautoflush = 1;
+					tx_packet = usb_malloc();
+					if (tx_packet) break;
+					tx_noautoflush = 0;
+				}
+				if (++wait_count > TX_TIMEOUT || transmit_previous_timeout) {
+					transmit_previous_timeout = 1;
+					return -1;
+				}
+				yield();
+			}
+		}
+		transmit_previous_timeout = 0;
+		len = CDC_TX_SIZE - tx_packet->index;
+		if (len > size) len = size;
+		dest = tx_packet->buf + tx_packet->index;
+		tx_packet->index += len;
+		size -= len;
+		while (len-- > 0) *dest++ = *src++;
+		if (tx_packet->index >= CDC_TX_SIZE) {
+			tx_packet->len = CDC_TX_SIZE;
+			usb_tx(CDC_TX_ENDPOINT, tx_packet);
+			tx_packet = NULL;
+		}
+		usb_cdc_transmit_flush_timer = TRANSMIT_FLUSH_TIMEOUT;
+	}
+	tx_noautoflush = 0;
+	return ret;
+}
+
+int usb_serial_write_buffer_free(void)
+{
+	uint32_t len;
+
+	tx_noautoflush = 1;
+	if (!tx_packet) {
+		if (!usb_configuration ||
+		  usb_tx_packet_count(CDC_TX_ENDPOINT) >= TX_PACKET_LIMIT ||
+		  (tx_packet = usb_malloc()) == NULL) {
+			tx_noautoflush = 0;
+			return 0;
+		}
+	}
+	len = CDC_TX_SIZE - tx_packet->index;
+	// TODO: Perhaps we need "usb_cdc_transmit_flush_timer = TRANSMIT_FLUSH_TIMEOUT"
+	// added here, so the SOF interrupt can't take away the available buffer
+	// space we just promised the user could write without blocking?
+	// But does this come with other performance downsides?  Could it lead to
+	// buffer data never actually transmitting in some usage cases?  More
+	// investigation is needed.
+	// https://github.com/PaulStoffregen/cores/issues/10#issuecomment-61514955
+	tx_noautoflush = 0;
+	return len;
+}
+
+void usb_serial_flush_output(void)
+{
+	if (!usb_configuration) return;
+	tx_noautoflush = 1;
+	if (tx_packet) {
+		usb_cdc_transmit_flush_timer = 0;
+		tx_packet->len = tx_packet->index;
+		usb_tx(CDC_TX_ENDPOINT, tx_packet);
+		tx_packet = NULL;
+	} else {
+		usb_packet_t *tx = usb_malloc();
+		if (tx) {
+			usb_cdc_transmit_flush_timer = 0;
+			usb_tx(CDC_TX_ENDPOINT, tx);
+		} else {
+			usb_cdc_transmit_flush_timer = 1;
+		}
+	}
+	tx_noautoflush = 0;
+}
+
+void usb_serial_flush_callback(void)
+{
+	if (tx_noautoflush) return;
+	if (tx_packet) {
+		tx_packet->len = tx_packet->index;
+		usb_tx(CDC_TX_ENDPOINT, tx_packet);
+		tx_packet = NULL;
+	} else {
+		usb_packet_t *tx = usb_malloc();
+		if (tx) {
+			usb_tx(CDC_TX_ENDPOINT, tx);
+		} else {
+			usb_cdc_transmit_flush_timer = 1;
+		}
+	}
+}
+
+
+
+
+#endif // F_CPU
+#endif // CDC_STATUS_INTERFACE && CDC_DATA_INTERFACE
diff --git a/motors/usb/usb_serial.h b/motors/usb/usb_serial.h
new file mode 100644
index 0000000..8367f05
--- /dev/null
+++ b/motors/usb/usb_serial.h
@@ -0,0 +1,172 @@
+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2017 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef USBserial_h_
+#define USBserial_h_
+
+#include "usb_desc.h"
+
+#if (defined(CDC_STATUS_INTERFACE) && defined(CDC_DATA_INTERFACE)) || defined(USB_DISABLED)
+
+#include <inttypes.h>
+
+#if F_CPU >= 20000000 && !defined(USB_DISABLED)
+
+// C language implementation
+#ifdef __cplusplus
+extern "C" {
+#endif
+int usb_serial_getchar(void);
+int usb_serial_peekchar(void);
+int usb_serial_available(void);
+int usb_serial_read(void *buffer, uint32_t size);
+void usb_serial_flush_input(void);
+int usb_serial_putchar(uint8_t c);
+int usb_serial_write(const void *buffer, uint32_t size);
+int usb_serial_write_buffer_free(void);
+void usb_serial_flush_output(void);
+extern uint32_t usb_cdc_line_coding[2];
+extern volatile uint32_t usb_cdc_line_rtsdtr_millis;
+extern volatile uint32_t systick_millis_count;
+extern volatile uint8_t usb_cdc_line_rtsdtr;
+extern volatile uint8_t usb_cdc_transmit_flush_timer;
+extern volatile uint8_t usb_configuration;
+#ifdef __cplusplus
+}
+#endif
+
+#define USB_SERIAL_DTR  0x01
+#define USB_SERIAL_RTS  0x02
+
+// C++ interface
+#ifdef __cplusplus
+#include "Stream.h"
+class usb_serial_class : public Stream
+{
+public:
+	constexpr usb_serial_class() {}
+        void begin(long) {
+		uint32_t millis_begin = systick_millis_count;
+		while (!(*this)) {
+			// wait up to 2.5 seconds for Arduino Serial Monitor
+			// Yes, this is a long time, but some Windows systems open
+			// the port very slowly.  This wait allows programs for
+			// Arduino Uno to "just work" (without forcing a reboot when
+			// the port is opened), and when no PC is connected the user's
+			// sketch still gets to run normally after this wait time.
+			if ((uint32_t)(systick_millis_count - millis_begin) > 2500) break;
+		}
+	}
+        void end() { /* TODO: flush output and shut down USB port */ };
+        virtual int available() { return usb_serial_available(); }
+        virtual int read() { return usb_serial_getchar(); }
+        virtual int peek() { return usb_serial_peekchar(); }
+        virtual void flush() { usb_serial_flush_output(); }  // TODO: actually wait for data to leave USB...
+        virtual void clear(void) { usb_serial_flush_input(); }
+        virtual size_t write(uint8_t c) { return usb_serial_putchar(c); }
+        virtual size_t write(const uint8_t *buffer, size_t size) { return usb_serial_write(buffer, size); }
+	size_t write(unsigned long n) { return write((uint8_t)n); }
+	size_t write(long n) { return write((uint8_t)n); }
+	size_t write(unsigned int n) { return write((uint8_t)n); }
+	size_t write(int n) { return write((uint8_t)n); }
+	virtual int availableForWrite() { return usb_serial_write_buffer_free(); }
+	using Print::write;
+        void send_now(void) { usb_serial_flush_output(); }
+        uint32_t baud(void) { return usb_cdc_line_coding[0]; }
+        uint8_t stopbits(void) { uint8_t b = usb_cdc_line_coding[1]; if (!b) b = 1; return b; }
+        uint8_t paritytype(void) { return usb_cdc_line_coding[1] >> 8; } // 0=none, 1=odd, 2=even
+        uint8_t numbits(void) { return usb_cdc_line_coding[1] >> 16; }
+        uint8_t dtr(void) { return (usb_cdc_line_rtsdtr & USB_SERIAL_DTR) ? 1 : 0; }
+        uint8_t rts(void) { return (usb_cdc_line_rtsdtr & USB_SERIAL_RTS) ? 1 : 0; }
+        operator bool() { return usb_configuration &&
+		(usb_cdc_line_rtsdtr & (USB_SERIAL_DTR | USB_SERIAL_RTS)) &&
+		((uint32_t)(systick_millis_count - usb_cdc_line_rtsdtr_millis) >= 25);
+	}
+	size_t readBytes(char *buffer, size_t length) {
+		size_t count=0;
+		unsigned long startMillis = millis();
+		do {
+			count += usb_serial_read(buffer + count, length - count);
+			if (count >= length) return count;
+		} while(millis() - startMillis < _timeout);
+		setReadError();
+		return count;
+	}
+
+};
+extern usb_serial_class Serial;
+extern void serialEvent(void);
+#endif // __cplusplus
+
+
+#else  // F_CPU < 20000000
+
+// Allow Arduino programs using Serial to compile, but Serial will do nothing.
+#ifdef __cplusplus
+#include "Stream.h"
+class usb_serial_class : public Stream
+{
+public:
+	constexpr usb_serial_class() {}
+        void begin(long) { };
+        void end() { };
+        virtual int available() { return 0; }
+        virtual int read() { return -1; }
+        virtual int peek() { return -1; }
+        virtual void flush() { }
+        virtual void clear() { }
+        virtual size_t write(uint8_t c) { return 1; }
+        virtual size_t write(const uint8_t *buffer, size_t size) { return size; }
+	size_t write(unsigned long n) { return 1; }
+	size_t write(long n) { return 1; }
+	size_t write(unsigned int n) { return 1; }
+	size_t write(int n) { return 1; }
+	int availableForWrite() { return 0; }
+	using Print::write;
+        void send_now(void) { }
+        uint32_t baud(void) { return 0; }
+        uint8_t stopbits(void) { return 1; }
+        uint8_t paritytype(void) { return 0; }
+        uint8_t numbits(void) { return 8; }
+        uint8_t dtr(void) { return 1; }
+        uint8_t rts(void) { return 1; }
+        operator bool() { return true; }
+};
+
+extern usb_serial_class Serial;
+extern void serialEvent(void);
+#endif // __cplusplus
+
+
+#endif // F_CPU
+
+#endif // CDC_STATUS_INTERFACE && CDC_DATA_INTERFACE
+
+#endif // USBserial_h_