diff --git a/src/osal/osal.h b/src/osal/osal.h
new file mode 100644
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--- /dev/null
+++ b/src/osal/osal.h
@@ -0,0 +1,111 @@
+/* 
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Ha Thach (tinyusb.org)
+ *
+ * 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:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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.
+ *
+ * This file is part of the TinyUSB stack.
+ */
+
+#ifndef _TUSB_OSAL_H_
+#define _TUSB_OSAL_H_
+
+#ifdef __cplusplus
+ extern "C" {
+#endif
+
+/** \addtogroup group_osal
+ *  @{ */
+
+#include "common/tusb_common.h"
+
+// Return immediately
+#define OSAL_TIMEOUT_NOTIMEOUT     (0)
+// Default timeout
+#define OSAL_TIMEOUT_NORMAL        (10)
+// Wait forever
+#define OSAL_TIMEOUT_WAIT_FOREVER  (UINT32_MAX)
+
+#define OSAL_TIMEOUT_CONTROL_XFER  OSAL_TIMEOUT_WAIT_FOREVER
+
+typedef void (*osal_task_func_t)( void * );
+
+#if CFG_TUSB_OS == OPT_OS_NONE
+  #include "osal_none.h"
+#elif CFG_TUSB_OS == OPT_OS_FREERTOS
+  #include "osal_freertos.h"
+#elif CFG_TUSB_OS == OPT_OS_MYNEWT
+  #include "osal_mynewt.h"
+#elif CFG_TUSB_OS == OPT_OS_PICO
+  #include "osal_pico.h"
+#elif CFG_TUSB_OS == OPT_OS_RTTHREAD
+  #include "osal_rtthread.h"
+#elif CFG_TUSB_OS == OPT_OS_CUSTOM
+  #include "tusb_os_custom.h" // implemented by application
+#else
+  #error OS is not supported yet
+#endif
+
+//--------------------------------------------------------------------+
+// OSAL Porting API
+//--------------------------------------------------------------------+
+
+#if __GNUC__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wredundant-decls"
+#endif
+//------------- Semaphore -------------//
+static inline osal_semaphore_t osal_semaphore_create(osal_semaphore_def_t* semdef);
+static inline bool osal_semaphore_post(osal_semaphore_t sem_hdl, bool in_isr);
+static inline bool osal_semaphore_wait(osal_semaphore_t sem_hdl, uint32_t msec);
+
+static inline void osal_semaphore_reset(osal_semaphore_t sem_hdl); // TODO removed
+
+//------------- Mutex -------------//
+static inline osal_mutex_t osal_mutex_create(osal_mutex_def_t* mdef);
+static inline bool osal_mutex_lock (osal_mutex_t sem_hdl, uint32_t msec);
+static inline bool osal_mutex_unlock(osal_mutex_t mutex_hdl);
+
+//------------- Queue -------------//
+static inline osal_queue_t osal_queue_create(osal_queue_def_t* qdef);
+static inline bool osal_queue_receive(osal_queue_t qhdl, void* data);
+static inline bool osal_queue_send(osal_queue_t qhdl, void const * data, bool in_isr);
+static inline bool osal_queue_empty(osal_queue_t qhdl);
+#if __GNUC__
+#pragma GCC diagnostic pop
+#endif
+
+#if 0  // TODO remove subtask related macros later
+// Sub Task
+#define OSAL_SUBTASK_BEGIN
+#define OSAL_SUBTASK_END                    return TUSB_ERROR_NONE;
+
+#define STASK_RETURN(_error)                return _error;
+#define STASK_INVOKE(_subtask, _status)     (_status) = _subtask
+#define STASK_ASSERT(_cond)                 TU_VERIFY(_cond, TUSB_ERROR_OSAL_TASK_FAILED)
+#endif
+
+#ifdef __cplusplus
+ }
+#endif
+
+/** @} */
+
+#endif /* _TUSB_OSAL_H_ */