diff --git a/hal/lib/athena/EncoderInternal.h b/hal/lib/athena/EncoderInternal.h
new file mode 100644
index 0000000..76ec840
--- /dev/null
+++ b/hal/lib/athena/EncoderInternal.h
@@ -0,0 +1,76 @@
+/*----------------------------------------------------------------------------*/
+/* 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#pragma once
+
+#include <stdint.h>
+
+#include "HAL/Encoder.h"
+
+namespace hal {
+class Encoder {
+ public:
+  Encoder(HAL_Handle digitalSourceHandleA,
+          HAL_AnalogTriggerType analogTriggerTypeA,
+          HAL_Handle digitalSourceHandleB,
+          HAL_AnalogTriggerType analogTriggerTypeB, bool reverseDirection,
+          HAL_EncoderEncodingType encodingType, int32_t* status);
+  ~Encoder();
+
+  // CounterBase interface
+  int32_t Get(int32_t* status) const;
+  int32_t GetRaw(int32_t* status) const;
+  int32_t GetEncodingScale(int32_t* status) const;
+  void Reset(int32_t* status);
+  double GetPeriod(int32_t* status) const;
+  void SetMaxPeriod(double maxPeriod, int32_t* status);
+  bool GetStopped(int32_t* status) const;
+  bool GetDirection(int32_t* status) const;
+
+  double GetDistance(int32_t* status) const;
+  double GetRate(int32_t* status) const;
+  void SetMinRate(double minRate, int32_t* status);
+  void SetDistancePerPulse(double distancePerPulse, int32_t* status);
+  void SetReverseDirection(bool reverseDirection, int32_t* status);
+  void SetSamplesToAverage(int32_t samplesToAverage, int32_t* status);
+  int32_t GetSamplesToAverage(int32_t* status) const;
+
+  void SetIndexSource(HAL_Handle digitalSourceHandle,
+                      HAL_AnalogTriggerType analogTriggerType,
+                      HAL_EncoderIndexingType type, int32_t* status);
+
+  int32_t GetFPGAIndex() const { return m_index; }
+
+  int32_t GetEncodingScale() const { return m_encodingScale; }
+
+  double DecodingScaleFactor() const;
+
+  double GetDistancePerPulse() const { return m_distancePerPulse; }
+
+  HAL_EncoderEncodingType GetEncodingType() const { return m_encodingType; }
+
+ private:
+  void SetupCounter(HAL_Handle digitalSourceHandleA,
+                    HAL_AnalogTriggerType analogTriggerTypeA,
+                    HAL_Handle digitalSourceHandleB,
+                    HAL_AnalogTriggerType analogTriggerTypeB,
+                    bool reverseDirection, HAL_EncoderEncodingType encodingType,
+                    int32_t* status);
+
+  HAL_FPGAEncoderHandle m_encoder = HAL_kInvalidHandle;
+
+  HAL_CounterHandle m_counter = HAL_kInvalidHandle;
+
+  int32_t m_index = 0;
+
+  double m_distancePerPulse = 1.0;
+
+  HAL_EncoderEncodingType m_encodingType;
+
+  int32_t m_encodingScale;
+};
+}  // namespace hal