wpilibc/athena/include/Ultrasonic.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 <atomic>
#include <memory>
#include <set>
#include <string>
#include <thread>

#include "Counter.h"
#include "LiveWindow/LiveWindowSendable.h"
#include "PIDSource.h"
#include "SensorBase.h"

namespace frc {

class DigitalInput;
class DigitalOutput;

/**
 * Ultrasonic rangefinder class.
 * The Ultrasonic rangefinder measures absolute distance based on the round-trip
 * time of a ping generated by the controller. These sensors use two
 * transducers, a speaker and a microphone both tuned to the ultrasonic range. A
 * common ultrasonic sensor, the Daventech SRF04 requires a short pulse to be
 * generated on a digital channel. This causes the chirp to be emitted. A second
 * line becomes high as the ping is transmitted and goes low when the echo is
 * received. The time that the line is high determines the round trip distance
 * (time of flight).
 */
class Ultrasonic : public SensorBase,
                   public PIDSource,
                   public LiveWindowSendable {
 public:
  enum DistanceUnit { kInches = 0, kMilliMeters = 1 };

  Ultrasonic(DigitalOutput* pingChannel, DigitalInput* echoChannel,
             DistanceUnit units = kInches);

  Ultrasonic(DigitalOutput& pingChannel, DigitalInput& echoChannel,
             DistanceUnit units = kInches);

  Ultrasonic(std::shared_ptr<DigitalOutput> pingChannel,
             std::shared_ptr<DigitalInput> echoChannel,
             DistanceUnit units = kInches);
  Ultrasonic(int pingChannel, int echoChannel, DistanceUnit units = kInches);
  virtual ~Ultrasonic();

  void Ping();
  bool IsRangeValid() const;
  static void SetAutomaticMode(bool enabling);
  double GetRangeInches() const;
  double GetRangeMM() const;
  bool IsEnabled() const { return m_enabled; }
  void SetEnabled(bool enable) { m_enabled = enable; }

  double PIDGet() override;
  void SetPIDSourceType(PIDSourceType pidSource) override;
  void SetDistanceUnits(DistanceUnit units);
  DistanceUnit GetDistanceUnits() const;

  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;

 private:
  void Initialize();

  static void UltrasonicChecker();

  // Time (sec) for the ping trigger pulse.
  static constexpr double kPingTime = 10 * 1e-6;
  // Priority that the ultrasonic round robin task runs.
  static const int kPriority = 64;
  // Max time (ms) between readings.
  static constexpr double kMaxUltrasonicTime = 0.1;
  static constexpr double kSpeedOfSoundInchesPerSec = 1130.0 * 12.0;

  static std::thread
      m_thread;  // thread doing the round-robin automatic sensing
  static std::set<Ultrasonic*> m_sensors;       // ultrasonic sensors
  static std::atomic<bool> m_automaticEnabled;  // automatic round robin mode

  std::shared_ptr<DigitalOutput> m_pingChannel;
  std::shared_ptr<DigitalInput> m_echoChannel;
  bool m_enabled = false;
  Counter m_counter;
  DistanceUnit m_units;

  std::shared_ptr<ITable> m_table;
};

}  // namespace frc