IR TX / RX with 16F628

[NST]

Hi everybody,

I am working on a project for controlling some devices with a remote controller which use NEC protocol. I have written RX codes in CCS using the timers. I have tried to catch fall and rise points to generate two data column and a checksum. After I setup and execute the timer, I wait for signal go to low with while(IR_PIN). But pic doesn't response until this line. It always stays in eternal loop in spite of it's logic value becomes zero.

I confused up.

 

[Pommie]

Have you turned off the comparators CMCON=7;?
Is the pin set to input?
Is IR_PIN defined as a single bit?

A bit more information and some code would be useful.

Mike.

 

[NST]

Thank you Mike.

Yes I turned the comparators off. Here is my code;

#include <16f628a.h>
#fuses NOWDT, INTRC_IO, PUT, NOPROTECT, MCLR

#use delay (clock=4000000) //4 MHZ
#byte CMCON=0x07;

#define  IR_PIN  PIN_B0

unsigned char bitcount;

int32 ir_tempbyte_hi;
int16 ir_tempbyte_lo;
int16 headp,heads,rise,fall;

void ir_read(void);
void ir_get_rise(void);
void ir_get_fall(void);
void ir_build_bytes(void);


#int_ext
void  ext_int ()
{
   ir_read();
}


void ir_read(void)
{
   ir_tempbyte_hi=0;
   ir_tempbyte_lo=0;

   while(IR_PIN); // //Wait for minimal pre which stays low 
   
   ir_get_rise(); // Get headp & heads to see what protocol it is
   headp=rise;
   ir_get_fall();
   heads=fall;

   if ((headp>8800)&&(headp<9090)&&(heads>4200)&&(heads<4570)) // We got NEC Start Sequence
   {
      output_high(PIN_A2);
      ir_build_bytes(); // Now trying to read data bits
   }
   else
   {
      output_high(PIN_A2);
   }
}

void ir_get_rise(void)
{
   output_high(PIN_A7);
   setup_counters(RTCC_INTERNAL,RTCC_DIV_1);    // Get high
   setup_timer_1(T1_INTERNAL|T1_DIV_BY_1);
   set_timer1(0);
   while(!IR_PIN); // Wait for signal to go high
   rise = get_timer1();
   delay_ms(1000);
   output_low(PIN_A7);   
}

void ir_get_fall(void)
{
   output_high(PIN_A6);
   setup_counters(RTCC_INTERNAL,RTCC_DIV_1);   // Get low
   setup_timer_1(T1_INTERNAL|T1_DIV_BY_1);
   set_timer1(0);
   while(IR_PIN);          // Wait for signal to go low 
   fall = get_timer1();
   delay_ms(1000);
   output_low(PIN_A6);
}
void ir_build_bytes(void)
{
   for (bitcount=0;bitcount!=32;bitcount++)
   {
      ir_get_rise();
      ir_get_fall();
      
      if ((rise>450)&&(rise<650)&&(fall>1400)&&(fall<1655))
      {
         ir_tempbyte_hi|=1; // bit=1
      }
      else if ((rise>450)&&(rise<650)&&(fall>390)&&(fall<600)){;} // bit=0
      else return; // Byte Check Fault 
   }

   if (bitcount<31){ir_tempbyte_hi<<=1;}  // Don't shift last bit
   if (bitcount==32){output_high(PIN_A2);} // reception is valid
}

void main ()
{
   setup_CCP1(CCP_OFF);            // CCP1 unit outbound
   ext_int_edge(H_TO_L);           // INT_EXT is High to Low
   
   setup_timer_0(t1_disabled);
   setup_timer_1(t2_disabled);

   enable_interrupts(INT_EXT);     // INT_EXT interrupt inbound
   enable_interrupts(GLOBAL);      // All interrupts inbound
   
   while(1); //Stand by
}

 

[Pommie]

I'm afraid I'm not familiar with the compiler you are using. I assume it is the CCS compiler as it appears to clear the interrupt flags for you.

One thing I notice from your code is your ISR calls ir_read which calls ir_get_rise which has a 1 second delay in it!

If it helps, here is some code I wrote in C18 which reads a sony code

#define IR_in   PORTAbits.RA6
#define IR_tris TRISAbits.TRISA6

unsigned char GetPulse(void){
unsigned char count;
    count=0;
    IR_tris=1;
    while(IR_in==1); 
    while(IR_in==0){
        count++;
        Delay100TCYx(1);   //50uS assumes 8MHz
    }
    return count;
}

void GetIR(char *cmd,char *dev){
char i;
    *cmd=0;
    *dev=0;
    while(GetPulse()<40);    //wait for start pulse
    for(i=0;i<7;i++){
        *cmd=*cmd>>1;
        if(GetPulse()>18)
            *cmd|=0x40;
    }
    for(i=0;i<5;i++){
        *dev=*dev>>1;
        if(GetPulse()>18)
            *dev|=0x10;
    }
}

Mike.

 

[BeeBop]

One thing I notice is that you haven't disabled Low Voltage Programming in your config, add NOLVP to your fuses statement.

Also as Pommie points out, interrupts should be short and sweet. Perhaps a better method is to set a flag in the isr, then in your main check to see if the flag is set and if so, go to your subroutine from there.

 

[NST]

Thank you very much.