/////////////////////////////////////////////////////////////////////////
////                           Sony.C                                ////
////  Program to read Sony remote control and convert to ASCII       ////
////  This program uses the RTCC (timer0) to time a single pulse     ////
////  input to the PIC. It reads the Sony IR from pin 4 (port pin 3) ////
////  It outputs the ASCII serial on pin 7 (port pin 0).             ////
////  It was improved over previous version by limiting length of   /////
////  allowed start pulse and checking for valid values.           //////
/////////////////////////////////////////////////////////////////////////

#include <12C509.H>
#list
#fuses   PAR,NOPROTECT,NOWDT,INTRC,MCLR   /*for internal clock */
//#fuses   PAR,NOPROTECT,NOWDT,XT,MCLR    /* for external crystal/resonat*/
#use delay(clock=4000000)
#use rs232(baud=2400, xmit=PIN_B0)  
//#rom 0x03ff={0x0c40}		    /*w factor for EPROM devices*/
#define START_MIN 100 /* 16us X 120 = 2.0ms min start bit */
#define START_MAX 260 /* 16us X 260 = 4.2ms max start bit */
#define BITTIME 60    /* 16us X 63  = 1ms   700us = 0  1200us = 1  */
byte const valid_code[22] =
 {128,129,130,131,132,133,134,135,136,137,
 146,147,144,145,88,89,92,91,90,106,148,187};
byte time, n;
byte prev_value, value;
                            
byte check_for_valid( byte code){
    for(n=0;n<=21;n++){
    if(code==valid_code[n])
       return(1);
    }
    return(0);
}

void wait_for_high_to_low() {
   while(!input(PIN_B3)) ;      /* if it's high, wait for a low */ 
   delay_us(3);                 /* account for fall time */
   while(input(PIN_B3));        /* wait for signal to go high */
}

void wait_for_high() {
   delay_us(3);                 /* account for rise time */
   while(!input(PIN_B3));       /* wait for signal to go high */
}


main() {
   
   setup_counters( RTCC_INTERNAL, RTCC_DIV_16);
   do {
     value = 0;
     do {					/* start bit  */
        wait_for_high_to_low();			/* must be between 2-3ms */
        set_rtcc(0);
        wait_for_high();
        time = get_rtcc();
     } while ((time < START_MIN) || (time > START_MAX));
     
     for (n = 0 ; n <= 7 ; n++){              /*get data bits */	       
       wait_for_high_to_low();
       set_rtcc(0);
       wait_for_high();
       time = get_rtcc();
       if (time > BITTIME) 
          bit_set(value,n);
     }                         /*Get data bit 8        */
     bit_clear(value,6);       /* This code removes the value for bit 6*/
     wait_for_high_to_low();    /* and uses the value of bit 8 instead */
     set_rtcc(0);               /* bits 6,9,10, and 11 are ignored     */
     wait_for_high();
     time = get_rtcc();
     if (time > BITTIME) 
          bit_set(value,6);

     if(prev_value == value){	/* must be same twice in a row */
       if(check_for_valid(value)) /* must be one of valid codes */
          printf("%c", value);   /* output value to serial port in ASCII */       
     }
     prev_value = value;
   } while (TRUE);
}