\o/ working decoder for nec infrared control code.

[moodlight.git] / ircontrol.c

/* $Id: ircontrol.c,v 1.2 2010/06/27 22:20:39 simimeie Exp $
 * Functions for the infrared receiver
 *
 * The infrared receiver is connected to PB0 / PCINT0.
 */

#include <avr/io.h>
#include <avr/interrupt.h>
#include "ircontrol.h"
#include "timers.h"
#include "console.h"

/* NOTE1: Note that the signal we get from the sensor is inverted. If we
 * read a zero, it means there was infrared on, if we read a one, infrared
 * is off.
 * NOTE2: Only NEC is implemented here right now, because MY remote uses
 * that protocol. However, there may be references to RC5 because I had
 * already thought about that and just left them for possible future use. */

/* For RC5, one bit length is 1778 us, when it toggles we see half
 * of it, i.e. 889 us.
 * that equals around 7100 cpu cycles at 8 MHz. */
#define RC5HALFLENINCYCLES ((CPUFREQ * 889UL) / 1000000UL)

/* For NEC, we start with a 9000 us pulse, then 4500 us silence.
 * Then the bits follow:
 * a 0 is a 560 us pulse followed by 1690 us of silence.
 * a 1 is a 560 us pulse followed by  560 us of silence.
 * These values equal the following cpu cycle counts:
 *  9000 us = 72000 cc, 4500 us = 36000 cc, 560 us = 4480, 1690 us = 13520 cc
 */
#define NECSTARTLEN1 ((CPUFREQ *   9UL) / 1000UL)
#define NECSTARTLEN2 ((CPUFREQ *  45UL) / 10000UL)
#define NECPULSELEN  ((CPUFREQ *  56UL) / 100000UL)
#define NECONELEN    ((CPUFREQ * 112UL) / 100000UL)
#define NECZEROLEN   ((CPUFREQ * 225UL) / 100000UL)

/* the NEC code contains 4 bytes, sent with LSB first:
 * 0+1 are either the "extended address" or "address and inverted address".
 * 2 is the command code
 * 3 is the inverted command code
 */

static struct timestamp last0irqts;
static struct timestamp last1irqts;
static uint8_t lastpin = 0;
static uint8_t codebytes[4];
static uint8_t curcodebit = 0xff;

/* some example codes
root@moodlight# !NSB! 11111111 00001000 11011111 00100000  (r)
root@moodlight# !NSB! 11111111 00001000 01011111 10100000  (g)
root@moodlight# !NSB! 11111111 00001000 10011111 01100000  (b)
root@moodlight# !NSB! 11111111 00001000 00011111 11100000  (w)
*/

ISR(PCINT0_vect) {
  uint8_t v;
  struct timestamp curirqts;
  uint32_t ts1diff; /* distance from last 1 */
  uint32_t ts0diff; /* distance from last 0 */
  
  v = PINB & _BV(PB0);
  if (v == lastpin) {  /* No change visible - spurious interrupt */
    return;
  }
  curirqts = gettimestamp_noirq();
  ts1diff = ((uint32_t)curirqts.ticks << 16) + curirqts.partticks;
  ts0diff = ts1diff;
  ts1diff -= ((uint32_t)last1irqts.ticks << 16) + last1irqts.partticks;
  ts0diff -= ((uint32_t)last0irqts.ticks << 16) + last0irqts.partticks;
  if (v) { /* Infrared just went away! */
    if ((ts1diff >= (( 8 * NECSTARTLEN1) / 10))
     && (ts1diff <= ((12 * NECSTARTLEN1) / 10))) {
        /* NEC start bit */
        /* console_printpgm_P(PSTR("!NSB!")); */
        curcodebit = 0xfe; /* Wait for second part of start sequence */
    } else {
      if (curcodebit <= 32) { /* We're in a decoding attempt, so */
                              /* Check pulse length */
        if ((ts1diff < (( 8 * NECPULSELEN) / 10))
         || (ts1diff > ((12 * NECPULSELEN) / 10))) {
            /* WRONG */
            curcodebit = 0xff;
        }
      }
      if (curcodebit == 32) {
        if (codebytes[2] != (codebytes[3] ^ 0xff)) {
          console_printpgm_P(PSTR("!CRC!"));
        } else {
          /* Successful decode! */
          console_printpgm_P(PSTR(" DEC>"));
          console_printhex8(codebytes[0]);
          console_printhex8(codebytes[1]);
          console_printhex8(codebytes[2]);
          console_printhex8(codebytes[3]);
        }
      }
    }
    last0irqts = curirqts;
  } else { /* Infrared went on */
    if ((ts1diff >= (( 8 * NECZEROLEN) / 10))
     && (ts1diff <= ((12 * NECZEROLEN) / 10))) {
        /* console_printpgm_P(PSTR("0")); */
        if (curcodebit < 32) {
          curcodebit++;
        }
    } else if ((ts1diff >= (( 8 * NECONELEN) / 10))
            && (ts1diff <= ((12 * NECONELEN) / 10))) {
        /* console_printpgm_P(PSTR("1")); */
        if (curcodebit < 32) {
          codebytes[curcodebit >> 3] |= (1 << (curcodebit & 0x07));
          curcodebit++;
        } else {
          curcodebit = 0xff;
        }
    } else if ((ts0diff >= (( 8 * NECSTARTLEN2) / 10))
            && (ts0diff <= ((12 * NECSTARTLEN2) / 10))) {
        if (curcodebit == 0xfe) { /* voila, correct start sequence */
          curcodebit = 0;
          codebytes[0] = codebytes[1] = codebytes[2] = codebytes[3] = 0;
        }
    }
    last1irqts = curirqts;
  }
#if 0
  console_printpgm_P(PSTR("!"));
  console_printhex8(tsdiff >> 24);
  console_printhex8(tsdiff >> 16);
  console_printhex8(tsdiff >>  8);
  console_printhex8(tsdiff >>  0);
  console_printpgm_P(PSTR("!"));
#endif
#if 0
  if (tsdiff > ((24 * HALFRC5LENINCYCLES) / 10)) {
    /* Start of new transmission */
    console_printpgm_P(PSTR("!1["));
    console_printhex8(v);
    lastbit = 1;
  } else if (tsdiff > ((15 * HALFRC5LENINCYCLES) / 10)) {
    /* Different bit than last time */
    lastbit = !lastbit;
    if (lastbit) {
      console_printpgm_P(PSTR("1"));
    } else {
      console_printpgm_P(PSTR("0"));
    }
  } else if ((tsdiff < ((15 * HALFRC5LENINCYCLES) / 10))
          && (tsdiff > (( 5 * HALFRC5LENINCYCLES) / 10))) {
    /* Same bit as last time */
    if (lastbit) {
      console_printpgm_P(PSTR("1"));
    } else {
      console_printpgm_P(PSTR("0"));
    }
  }
#endif
  lastpin = v;
}

void ircontrol_init(void)
{
  /* Activate pullup */
  PORTB |= _BV(PB0);
  /* enable PCINT0 */
  PCICR |= _BV(PCIE0);
  /* Enable pin change interrupt 0 (=PB0) in pcint0 */
  PCMSK0 |= _BV(PCINT0);
}