wpilibc/Athena/include/Encoder.h

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2016. 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 "HAL/HAL.hpp"
#include "CounterBase.h"
#include "SensorBase.h"
#include "Counter.h"
#include "PIDSource.h"
#include "LiveWindow/LiveWindowSendable.h"

#include <memory>

class DigitalSource;
class DigitalGlitchFilter;

/**
 * Class to read quad encoders.
 * Quadrature encoders are devices that count shaft rotation and can sense
 * direction. The output of
 * the QuadEncoder class is an integer that can count either up or down, and can
 * go negative for
 * reverse direction counting. When creating QuadEncoders, a direction is
 * supplied that changes the
 * sense of the output to make code more readable if the encoder is mounted such
 * that forward movement
 * generates negative values. Quadrature encoders have two digital outputs, an A
 * Channel and a B Channel
 * that are out of phase with each other to allow the FPGA to do direction
 * sensing.
 *
 * All encoders will immediately start counting - Reset() them if you need them
 * to be zeroed before use.
 */
class Encoder : public SensorBase,
                public CounterBase,
                public PIDSource,
                public LiveWindowSendable {
 public:
  enum IndexingType {
    kResetWhileHigh,
    kResetWhileLow,
    kResetOnFallingEdge,
    kResetOnRisingEdge
  };

  Encoder(uint32_t aChannel, uint32_t bChannel, bool reverseDirection = false,
          EncodingType encodingType = k4X);
  Encoder(std::shared_ptr<DigitalSource> aSource,
          std::shared_ptr<DigitalSource> bSource,
          bool reverseDirection = false, EncodingType encodingType = k4X);
  Encoder(DigitalSource *aSource, DigitalSource *bSource,
          bool reverseDirection = false, EncodingType encodingType = k4X);
  Encoder(DigitalSource &aSource, DigitalSource &bSource,
          bool reverseDirection = false, EncodingType encodingType = k4X);
  virtual ~Encoder();

  // CounterBase interface
  int32_t Get() const override;
  int32_t GetRaw() const;
  int32_t GetEncodingScale() const;
  void Reset() override;
  double GetPeriod() const override;
  void SetMaxPeriod(double maxPeriod) override;
  bool GetStopped() const override;
  bool GetDirection() const override;

  double GetDistance() const;
  double GetRate() const;
  void SetMinRate(double minRate);
  void SetDistancePerPulse(double distancePerPulse);
  void SetReverseDirection(bool reverseDirection);
  void SetSamplesToAverage(int samplesToAverage);
  int GetSamplesToAverage() const;
  double PIDGet() override;

  void SetIndexSource(uint32_t channel, IndexingType type = kResetOnRisingEdge);
  DEPRECATED("Use pass-by-reference instead.")
  void SetIndexSource(DigitalSource *source,
                      IndexingType type = kResetOnRisingEdge);
  void SetIndexSource(const DigitalSource &source,
                      IndexingType type = kResetOnRisingEdge);

  void UpdateTable() override;
  void StartLiveWindowMode() override;
  void StopLiveWindowMode() override;
  std::string GetSmartDashboardType() const override;
  void InitTable(std::shared_ptr<ITable> subTable) override;
  std::shared_ptr<ITable> GetTable() const override;

  int32_t GetFPGAIndex() const { return m_index; }

 private:
  void InitEncoder(bool _reverseDirection, EncodingType encodingType);
  double DecodingScaleFactor() const;

  std::shared_ptr<DigitalSource> m_aSource; // the A phase of the quad encoder
  std::shared_ptr<DigitalSource> m_bSource; // the B phase of the quad encoder
  void *m_encoder = nullptr;
  int32_t m_index = 0;             // The encoder's FPGA index.
  double m_distancePerPulse = 1.0; // distance of travel for each encoder tick
  std::unique_ptr<Counter> m_counter =
      nullptr;                     // Counter object for 1x and 2x encoding
  EncodingType m_encodingType;     // Encoding type
  int32_t m_encodingScale;         // 1x, 2x, or 4x, per the encodingType

  std::shared_ptr<ITable> m_table;
  friend class DigitalGlitchFilter;
};