IRsnd.h

//******************************************************************************
// IRremote
// Origial code by Ken Shirriff
// Modified by Paul Stoffregen <paul@pjrc.com> to support other boards and timers
// Modified by Michael Rickert <Slacker87> for more accurate IR LED timings
// Interrupt code based on NECIRrcv by Joe Knapp
//******************************************************************************

#include "IRinit.h"

//------------------------------------------------------------------------------
// Main class for sending IR
//
class IRsend
{
  public:
    IRsend () { }

    void  custom_delay_usec (unsigned long uSecs);
    void  enableIROut     (int khz) ;
    void  mark            (unsigned int usec) ;
    void  space           (unsigned int usec) ;
    void  sendRaw         (const unsigned int buf[],  unsigned int len,  unsigned int hz) ;
} ;

//+=============================================================================
void  IRsend::sendRaw (const unsigned int buf[],  unsigned int len,  unsigned int hz)
{
  // Set IR carrier frequency
  enableIROut(hz);

  for (unsigned int i = 0;  i < len;  i++) {
    if (i & 1)  space(buf[i]) ;
    else        mark (buf[i]) ;
  }

  space(0);  // Always end with the LED off
}

//+=============================================================================
// Sends an IR mark for the specified number of microseconds.
// The mark output is modulated at the PWM frequency.
//
void  IRsend::mark (unsigned int time)
{
  TIMER_ENABLE_PWM; // Enable pin 3 PWM output
  if (time > 0) custom_delay_usec(time);
}

//+=============================================================================
// Leave pin off for time (given in microseconds)
// Sends an IR space for the specified number of microseconds.
// A space is no output, so the PWM output is disabled.
//
void  IRsend::space (unsigned int time)
{
  TIMER_DISABLE_PWM; // Disable pin 3 PWM output
  if (time > 0) IRsend::custom_delay_usec(time);
}

//+=============================================================================
// Enables IR output.  The khz value controls the modulation frequency in kilohertz.
// The IR output will be on pin 3 (OC2B).
// This routine is designed for 36-40KHz; if you use it for other values, it's up to you
// to make sure it gives reasonable results.  (Watch out for overflow / underflow / rounding.)
// TIMER2 is used in phase-correct PWM mode, with OCR2A controlling the frequency and OCR2B
// controlling the duty cycle.
// There is no prescaling, so the output frequency is 16MHz / (2 * OCR2A)
// To turn the output on and off, we leave the PWM running, but connect and disconnect the output pin.
// A few hours staring at the ATmega documentation and this will all make sense.
// See my Secrets of Arduino PWM at http://arcfn.com/2009/07/secrets-of-arduino-pwm.html for details.
//
void  IRsend::enableIROut (int khz)
{
  pinMode(TIMER_PWM_PIN, OUTPUT);
  digitalWrite(TIMER_PWM_PIN, LOW); // When not sending PWM, we want it low
  TIMER_CONFIG_KHZ(khz);
}

//+=============================================================================
// Custom delay function that circumvents Arduino's delayMicroseconds limit
//
void IRsend::custom_delay_usec(unsigned long uSecs) {
  if (uSecs > 4) {
    unsigned long start = micros();
    unsigned long endMicros = start + uSecs - 4;
    if (endMicros < start) { // Check if overflow
      while ( micros() > start ) {} // wait until overflow
    }
    while ( micros() < endMicros ) {} // normal wait
  } 
}