diff --git a/hal/lib/athena/DigitalInternal.cpp b/hal/lib/athena/DigitalInternal.cpp
new file mode 100644
index 0000000..01e6c16
--- /dev/null
+++ b/hal/lib/athena/DigitalInternal.cpp
@@ -0,0 +1,160 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2016-2017. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "DigitalInternal.h"
+
+#include <atomic>
+#include <mutex>
+#include <thread>
+
+#include "ConstantsInternal.h"
+#include "FRC_NetworkCommunication/LoadOut.h"
+#include "HAL/AnalogTrigger.h"
+#include "HAL/ChipObject.h"
+#include "HAL/HAL.h"
+#include "HAL/Ports.h"
+#include "HAL/cpp/priority_mutex.h"
+#include "PortsInternal.h"
+
+namespace hal {
+// Create a mutex to protect changes to the DO PWM config
+priority_recursive_mutex digitalPwmMutex;
+
+std::unique_ptr<tDIO> digitalSystem;
+std::unique_ptr<tRelay> relaySystem;
+std::unique_ptr<tPWM> pwmSystem;
+std::unique_ptr<tSPI> spiSystem;
+
+static std::atomic<bool> digitalSystemsInitialized{false};
+static priority_mutex initializeMutex;
+
+DigitalHandleResource<HAL_DigitalHandle, DigitalPort,
+                      kNumDigitalChannels + kNumPWMHeaders>
+    digitalChannelHandles;
+
+/**
+ * Initialize the digital system.
+ */
+void initializeDigital(int32_t* status) {
+  // Initial check, as if it's true initialization has finished
+  if (digitalSystemsInitialized) return;
+
+  std::lock_guard<priority_mutex> lock(initializeMutex);
+  // Second check in case another thread was waiting
+  if (digitalSystemsInitialized) return;
+
+  digitalSystem.reset(tDIO::create(status));
+
+  // Relay Setup
+  relaySystem.reset(tRelay::create(status));
+
+  // Turn off all relay outputs.
+  relaySystem->writeValue_Forward(0, status);
+  relaySystem->writeValue_Reverse(0, status);
+
+  // PWM Setup
+  pwmSystem.reset(tPWM::create(status));
+
+  // Make sure that the 9403 IONode has had a chance to initialize before
+  // continuing.
+  while (pwmSystem->readLoopTiming(status) == 0) std::this_thread::yield();
+
+  if (pwmSystem->readLoopTiming(status) != kExpectedLoopTiming) {
+    *status = LOOP_TIMING_ERROR;  // NOTE: Doesn't display the error
+  }
+
+  // Calculate the length, in ms, of one DIO loop
+  double loopTime = pwmSystem->readLoopTiming(status) /
+                    (kSystemClockTicksPerMicrosecond * 1e3);
+
+  pwmSystem->writeConfig_Period(
+      static_cast<uint16_t>(kDefaultPwmPeriod / loopTime + .5), status);
+  uint16_t minHigh = static_cast<uint16_t>(
+      (kDefaultPwmCenter - kDefaultPwmStepsDown * loopTime) / loopTime + .5);
+  pwmSystem->writeConfig_MinHigh(minHigh, status);
+  // Ensure that PWM output values are set to OFF
+  for (uint8_t pwmIndex = 0; pwmIndex < kNumPWMChannels; pwmIndex++) {
+    // Copy of SetPWM
+    if (pwmIndex < tPWM::kNumHdrRegisters) {
+      pwmSystem->writeHdr(pwmIndex, kPwmDisabled, status);
+    } else {
+      pwmSystem->writeMXP(pwmIndex - tPWM::kNumHdrRegisters, kPwmDisabled,
+                          status);
+    }
+
+    // Copy of SetPWMPeriodScale, set to 4x by default.
+    if (pwmIndex < tPWM::kNumPeriodScaleHdrElements) {
+      pwmSystem->writePeriodScaleHdr(pwmIndex, 3, status);
+    } else {
+      pwmSystem->writePeriodScaleMXP(
+          pwmIndex - tPWM::kNumPeriodScaleHdrElements, 3, status);
+    }
+  }
+
+  // SPI setup
+  spiSystem.reset(tSPI::create(status));
+
+  digitalSystemsInitialized = true;
+}
+
+/**
+ * Map SPI channel numbers from their physical number (27 to 31) to their
+ * position in the bit field.
+ */
+int32_t remapSPIChannel(int32_t channel) { return channel - 26; }
+
+/**
+ * Map DIO channel numbers from their physical number (10 to 26) to their
+ * position in the bit field.
+ */
+int32_t remapMXPChannel(int32_t channel) { return channel - 10; }
+
+int32_t remapMXPPWMChannel(int32_t channel) {
+  if (channel < 14) {
+    return channel - 10;  // first block of 4 pwms (MXP 0-3)
+  } else {
+    return channel - 6;  // block of PWMs after SPI
+  }
+}
+
+/**
+ * remap the digital source channel and set the module.
+ * If it's an analog trigger, determine the module from the high order routing
+ * channel else do normal digital input remapping based on channel number
+ * (MXP)
+ */
+bool remapDigitalSource(HAL_Handle digitalSourceHandle,
+                        HAL_AnalogTriggerType analogTriggerType,
+                        uint8_t& channel, uint8_t& module,
+                        bool& analogTrigger) {
+  if (isHandleType(digitalSourceHandle, HAL_HandleEnum::AnalogTrigger)) {
+    // If handle passed, index is not negative
+    int32_t index = getHandleIndex(digitalSourceHandle);
+    channel = (index << 2) + analogTriggerType;
+    module = channel >> 4;
+    analogTrigger = true;
+    return true;
+  } else if (isHandleType(digitalSourceHandle, HAL_HandleEnum::DIO)) {
+    int32_t index = getHandleIndex(digitalSourceHandle);
+    if (index > kNumDigitalHeaders + kNumDigitalMXPChannels) {
+      // channels 10-15, so need to add headers to remap index
+      channel = remapSPIChannel(index) + kNumDigitalHeaders;
+      module = 0;
+    } else if (index >= kNumDigitalHeaders) {
+      channel = remapMXPChannel(index);
+      module = 1;
+    } else {
+      channel = index;
+      module = 0;
+    }
+    analogTrigger = false;
+    return true;
+  } else {
+    return false;
+  }
+}
+}  // namespace hal