HCSR04.hh

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#ifndef COSA_HCSR04_HH
#define COSA_HCSR04_HH

#include "Cosa/Types.h"
#include "Cosa/InputPin.hh"
#include "Cosa/OutputPin.hh"
#include "Cosa/Periodic.hh"
#include "Cosa/Watchdog.hh"

class HCSR04 : public Periodic {
public:
  HCSR04(Job::Scheduler* scheduler,
         Board::DigitalPin trigger,
         Board::DigitalPin echo) :
    Periodic(scheduler, 250),
    m_trigger(trigger),
    m_echo(echo),
    m_distance(0)
  {}

  uint16_t distance() const
  {
    return (m_distance);
  }

  bool read(uint16_t& distance);

  void schedule(uint16_t ms)
    __attribute__((always_inline))
  {
    stop();
    period(ms);
    expire_after(ms);
    start();
  }

  virtual void on_change(uint16_t distance)
  {
    UNUSED(distance);
  }

private:
  static const uint16_t TIMEOUT = 0xffffU;

  static const uint16_t COUNT_PER_DM = (555 * I_CPU) / 16;

  OutputPin m_trigger;

  InputPin m_echo;

  uint16_t m_distance;

  virtual void on_event(uint8_t type, uint16_t value);
};

#endif