AnalogComparator.hh

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#ifndef COSA_ANALOG_COMPARATOR_HH
#define COSA_ANALOG_COMPARATOR_HH

#include "Cosa/Event.hh"
#include "Cosa/Interrupt.hh"

class AnalogComparator : public Interrupt::Handler, public Event::Handler {
public:
  enum Mode {
    ON_TOGGLE_MODE = 0,
    ON_FALLING_MODE = _BV(ACIS1),
    ON_RISING_MODE = (_BV(ACIS1) | _BV(ACIS0)),
  } __attribute__((packed));

  AnalogComparator(Mode mode = ON_TOGGLE_MODE, bool bandgap = false) :
    m_mode(mode),
    m_pin(bandgap ? VBG : AIN1)
  {}

  AnalogComparator(Board::AnalogPin pin, Mode mode = ON_TOGGLE_MODE) :
    m_mode(mode),
    m_pin((uint8_t) (pin - Board::A0))
  {}

  virtual void enable()
  {
    synchronized {
      s_comparator = this;
      ADCSRB = (m_pin >= AIN1) ? 0 : (_BV(ACME) | m_pin);
      if (m_pin == VBG)
        ACSR = _BV(ACBG) | _BV(ACIE) | m_mode;
      else
        ACSR = _BV(ACIE) | m_mode;
    }
  }

  virtual void disable()
  {
    synchronized {
      ACSR = _BV(ACD);
      s_comparator = NULL;
    }
  }

  virtual void on_interrupt(uint16_t arg = 0);

protected:
  static AnalogComparator* s_comparator; 
  static const uint8_t AIN1 = 254;       
  static const uint8_t VBG = 255;        
  Mode m_mode;                           
  uint8_t m_pin;                         

  friend void ANALOG_COMP_vect(void);
};

#endif