133 lines
3.3 KiB
C
133 lines
3.3 KiB
C
/* Name: main.c
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* Author: Justin R. Cutler <justin.r.cutler@gmail.com>
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* Copyright: 2012 Justin R. Cutler
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* License: GPLv3
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* ATtiny25/45/85 connections:
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*
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* +-\/-+
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* Vcc 1|o |8 Vcc
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* NC 2| |7 NC
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* NC 3| |6 IR_TX
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* GND 4| |5 IR_RX
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* +----+
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*
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* The ATtiny85 (http://www.sparkfun.com/products/9378) is generally the easiest
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* to find 8-pin DIP AVR.
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*
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* IR_RX should be connected to the output pin of an IR Receiver Diode such as:
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* - TSOP85338 IR Receiver Breakout (http://www.sparkfun.com/products/8554)
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* - TSOP38238 IR Receiver Diode (http://www.sparkfun.com/products/10266)
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*
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* IR_TX should be connected to a current-limited IR LED or a high-power
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* switched LED, such as:
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* - LED Infrared 950nm (https://www.sparkfun.com/products/9349) with a 330 Ohm
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* resistor
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* - Max Power IR LED Kit (http://www.sparkfun.com/products/10732)
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*
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* The IR Control Kit Retail (http://www.sparkfun.com/products/10783) from
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* SparkFun Electronics contains everything you need to get started, other than
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* the ATtiny25/45/85.
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*/
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#include <avr/interrupt.h>
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#include <avr/io.h>
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#include <avr/sleep.h>
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/* IR modulation frequency (in Hz) */
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#define IR_MODULATION 38000
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/* IR receive pin (demodulated, negative logic) */
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#define IR_RX PINB0
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/* IR transmit pin */
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#define IR_TX PINB1
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/* enable modulated IR transmit (via Timer1) */
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#define IR_TX_ON() do { TCCR1 |= _BV(COM1A1); } while (0)
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/* disable modulated IR transmit (via Timer1) */
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#define IR_TX_OFF() do { TCCR1 &= ~_BV(COM1A1); } while (0)
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/* IR receiver pin change interrupt */
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ISR(PCINT0_vect)
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{
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/* test IR_RX pin (negative logic) */
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if (PINB & _BV(IR_RX))
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{
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IR_TX_OFF();
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}
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else
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{
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IR_TX_ON();
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}
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}
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void setup(void)
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{
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/*
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* IR receiver setup
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*/
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/* set IR_RX as input */
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DDRB &= _BV(IR_RX);
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/* enable interrupt on change of IR_RX */
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PCMSK |= _BV(PCINT0);
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GIMSK |= _BV(PCIE);
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/*
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* IR transmitter setup
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*/
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/* enable IR modulation (~33% duty cycle) via Timer1 */
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TCCR1 = _BV(PWM1A) | _BV(CS12);
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OCR1C = (((F_CPU / 8 / IR_MODULATION)) - 1);
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OCR1A = OCR1C / 3;
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/* set IR_TX as output */
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DDRB |= _BV(IR_TX);
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/* turn IR_TX off when not enabled */
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PORTB &= ~_BV(IR_TX);
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/*
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* Power saving
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*/
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/* disable unnecessary hardware */
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PRR |= _BV(PRADC) | _BV(PRUSI);
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/* enable idle sleep mode */
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set_sleep_mode(SLEEP_MODE_IDLE);
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}
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int main(void)
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{
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/* initialize hardware */
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setup();
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/* enable interrupts */
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sei();
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for (;;)
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{
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/* go to sleep (all work done in PCINT0 ISR) */
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sleep_mode();
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}
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return 0; /* never reached */
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}
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