Timing RC5 decodieren nach Peter Dannegger

C-Code

#ifndef F_CPU

#define F_CPU 4000000UL

#endif

#define timer0_start TCCR0B = 0x01 //keinen teiler 80 alle 10µs

#define timer0_stopp TCCR0B = 0x00

#define timer0  TCNT0

#define timer1_start TCCR1 = 0x03 //64

#define timer1_stopp TCCR1 = 0x00

#define timer1  TCNT1

#define RC5TIME   1.778e-3    // 1.778msec

#define PULSE_MIN  (uchar)(XTAL / 512 * RC5TIME * 0.4 + 0.5)

#define PULSE_1_2  (uchar)(XTAL / 512 * RC5TIME * 0.8 + 0.5)

#define PULSE_MAX  (uchar)(XTAL / 512 * RC5TIME * 1.2 + 0.5)

//min = 889µs/26 T/aufrufinterwall

#include <avr/io.h>

#include <stdint.h>

#include <avr/interrupt.h>

#include <util/delay.h>

#include <stdbool.h>

#include <avr/interrupt.h>

#include <stdlib.h>

#define uchar unsigned char

#define uint unsigned int

#define  xRC5_IN    PINB

#define  xRC5    PB2    // IR input low active

#define  XTAL    11.0592e6

uchar  rc5_bit;        // bit value

uchar  rc5_time;        // count bit time

uint  rc5_tmp;        // shift bits in

volatile uint rc5_data;        // store result

SIGNAL (SIG_OVERFLOW0)

{

PORTB |= (1<<PB4) ; // set

  //volatile uint tmp = rc5_tmp;        // for faster access

  TCNT0 = -2;          // 2 * 256 = 512 cycle

  if( ++rc5_time > PULSE_MAX ){      // count pulse time

    if( !(rc5_data & 0x4000) && rc5_data & 0x2000 )  // only if 14 bits received

    rc5_data = rc5_data;

    rc5_data = 0;

  }

  if( (rc5_bit ^ xRC5_IN) & 1<<xRC5 ){    // change detect

    rc5_bit = ~rc5_bit;        // 0x00 -> 0xFF -> 0x00

    if( rc5_time < PULSE_MIN )      // to short

    rc5_data = 0;

    if( !rc5_data || rc5_time > PULSE_1_2 ){    // start or long pulse time

      if( !(rc5_data & 0x4000) )      // not to many bits

      rc5_data <<= 1;        // shift

      if( !(rc5_bit & 1<<xRC5) )    // inverted bit

      rc5_data |= 1;        // insert new bit

      rc5_time = 0;        // count next pulse time

    }

  }

  rc5_tmp = rc5_data;

PORTB &= ~(1<<PB4); //reset

}

int main(void)

{

  DDRB = 0b111011; //Schieberegisterports als Ausgang PB2 di

        PORTB = 0b000100; // Pull up pb2 ein

        TCCR0B = 1<<CS02;      //divide by 256

        TIMSK = 1<<TOIE0;      //enable timer interrupt

        sei();

}

  while(1)

  {

          asm("nop");

        }