93 lines
1.7 KiB
C
93 lines
1.7 KiB
C
/* Name: main.c
|
|
* Author: Justin R. Cutler <justin.r.cutler@gmail.com>
|
|
* Copyright: 2012 Justin R. Cutler
|
|
* License: GPL
|
|
*/
|
|
|
|
#include <avr/interrupt.h>
|
|
#include <avr/io.h>
|
|
#include <avr/sleep.h>
|
|
|
|
|
|
/* IR modulation frequency (in Hz) */
|
|
#define IR_MODULATION 38000
|
|
|
|
/* IR receive pin (demodulated, negative logic) */
|
|
#define IR_RX PINB0
|
|
/* IR transmit pin */
|
|
#define IR_TX PINB1
|
|
|
|
/* enable modulated IR transmit (via Timer1) */
|
|
#define IR_TX_ON() do { TCCR1 |= _BV(COM1A1); } while (0)
|
|
/* disable modulated IR transmit (via Timer1) */
|
|
#define IR_TX_OFF() do { TCCR1 &= ~_BV(COM1A1); } while (0)
|
|
|
|
|
|
/* IR receiver pin change interrupt */
|
|
ISR(PCINT0_vect)
|
|
{
|
|
/* test IR_RX pin (negative logic) */
|
|
if (PINB & _BV(IR_RX))
|
|
{
|
|
IR_TX_OFF();
|
|
}
|
|
else
|
|
{
|
|
IR_TX_ON();
|
|
}
|
|
}
|
|
|
|
|
|
void setup(void)
|
|
{
|
|
/*
|
|
* IR receiver setup
|
|
*/
|
|
|
|
/* set IR_RX as input */
|
|
DDRB &= _BV(IR_RX);
|
|
/* enable interrupt on change of IR_RX */
|
|
PCMSK |= _BV(PCINT0);
|
|
GIMSK |= _BV(PCIE);
|
|
|
|
/*
|
|
* IR transmitter setup
|
|
*/
|
|
|
|
/* enable IR modulation (50% duty cycle) via Timer1 */
|
|
TCCR1 = _BV(PWM1A) | _BV(CS12);
|
|
OCR1C = (((F_CPU / 8 / IR_MODULATION)) - 1);
|
|
OCR1A = OCR1C / 2;
|
|
/* set IR_TX as output */
|
|
DDRB |= _BV(IR_TX);
|
|
/* turn IR_TX off when not enabled */
|
|
PORTB &= ~_BV(IR_TX);
|
|
|
|
/*
|
|
* Power saving
|
|
*/
|
|
|
|
/* disable unnecessary hardware */
|
|
PRR |= _BV(PRADC) | _BV(PRUSI);
|
|
/* enable idle sleep mode */
|
|
set_sleep_mode(SLEEP_MODE_IDLE);
|
|
}
|
|
|
|
|
|
int main(void)
|
|
{
|
|
/* initialize hardware */
|
|
setup();
|
|
|
|
/* enable interrupts */
|
|
sei();
|
|
|
|
for (;;)
|
|
{
|
|
/* go to sleep (all work done in PCINT0 ISR) */
|
|
sleep_mode();
|
|
}
|
|
|
|
return 0; /* never reached */
|
|
}
|