wpilibc/sim/include/PWM.h

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2017. 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 <memory>
#include <string>

#include "LiveWindow/LiveWindowSendable.h"
#include "SensorBase.h"
#include "simulation/SimContinuousOutput.h"
#include "tables/ITableListener.h"

namespace frc {

/**
 * Class implements the PWM generation in the FPGA.
 *
 * The values supplied as arguments for PWM outputs range from -1.0 to 1.0. They
 * are mapped to the hardware dependent values, in this case 0-255 for the FPGA.
 * Changes are immediately sent to the FPGA, and the update occurs at the next
 * FPGA cycle. There is no delay.
 *
 * As of revision 0.1.10 of the FPGA, the FPGA interprets the 0-255 values as
 * follows:
 *   - 255 = full "forward"
 *   - 254 to 129 = linear scaling from "full forward" to "center"
 *   - 128 = center value
 *   - 127 to 2 = linear scaling from "center" to "full reverse"
 *   - 1 = full "reverse"
 *   - 0 = disabled (i.e. PWM output is held low)
 */
class PWM : public SensorBase,
            public ITableListener,
            public LiveWindowSendable {
 public:
  enum PeriodMultiplier {
    kPeriodMultiplier_1X = 1,
    kPeriodMultiplier_2X = 2,
    kPeriodMultiplier_4X = 4
  };

  explicit PWM(int channel);
  virtual ~PWM();
  virtual void SetRaw(uint16_t value);
  void SetPeriodMultiplier(PeriodMultiplier mult);
  void EnableDeadbandElimination(bool eliminateDeadband);
  void SetBounds(int max, int deadbandMax, int center, int deadbandMin,
                 int min);
  void SetBounds(double max, double deadbandMax, double center,
                 double deadbandMin, double min);
  int GetChannel() const { return m_channel; }

 protected:
  /**
   * kDefaultPwmPeriod is in ms
   *
   * - 20ms periods (50 Hz) are the "safest" setting in that this works for all
   *   devices
   * - 20ms periods seem to be desirable for Vex Motors
   * - 20ms periods are the specified period for HS-322HD servos, but work
   *   reliably down to 10.0 ms; starting at about 8.5ms, the servo sometimes
   *   hums and get hot; by 5.0ms the hum is nearly continuous
   * - 10ms periods work well for Victor 884
   * - 5ms periods allows higher update rates for Luminary Micro Jaguar speed
   *   controllers. Due to the shipping firmware on the Jaguar, we can't run
   *   the update period less than 5.05 ms.
   *
   * kDefaultPwmPeriod is the 1x period (5.05 ms).  In hardware, the period
   * scaling is implemented as an output squelch to get longer periods for old
   * devices.
   */
  static const double kDefaultPwmPeriod;
  /**
   * kDefaultPwmCenter is the PWM range center in ms
   */
  static const double kDefaultPwmCenter;
  /**
   * kDefaultPWMStepsDown is the number of PWM steps below the centerpoint
   */
  static const int kDefaultPwmStepsDown;
  static const int kPwmDisabled;

  virtual void SetPosition(double pos);
  virtual double GetPosition() const;
  virtual void SetSpeed(double speed);
  virtual double GetSpeed() const;

  bool m_eliminateDeadband;
  int m_centerPwm;

  void ValueChanged(ITable* source, llvm::StringRef key,
                    std::shared_ptr<nt::Value> value, bool isNew) override;
  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;

  std::shared_ptr<ITable> m_table;

 private:
  int m_channel;
  SimContinuousOutput* impl;
};

}  // namespace frc