Delay Using Timer1 pic 16f628a + CCS compiler PCM 4.068

[raflab]

I'm trying to create a delay with N minutes using timer 1 .. I found the following code

#include <16F628A.h> 
#fuses INTRC_IO, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP 
#use delay(clock=4000000) 

//====================== 
void main() 
{ 
int16 delay = 0; 

SET_TIMER1(delay); 

SETUP_TIMER_1(T1_INTERNAL | T1_DIV_BY_8); 

while(TRUE) 
  { 
   if(GET_TIMER1() <32768) 
      OUTPUT_LOW(PIN_A1); 
   if(GET_TIMER1() >32768) 
      OUTPUT_HIGH(PIN_A1); 
  } 
}

So if is it possible I want to replace the 0.5 sec by 2 minutes ( for example )
( I said N minutes because that's related to the user that he will be able to send it through VB interface using Serial port communication )
I won't use the delay_ms because it will be imprecise
I really need some help !! :-|
Thanks

 

[sarge]

For quartz 4MHz vs TMR1 maximum possible delay is 524,28ms
But you can make variable counter, for example i:

   while(1) {  
      
     //procedure setting timer1 (tmr1h tmr1l = 62500)
     if(TMR1IF) { i++; TMR1IF = 0;}    // I'm not sure for this in CCS
     
     if (i == N) {                                // where N - time in seconds
                     PIN_A1 = !PIN_A1; 
                     i = 0;
                     }
         
    
      
   }

And best choice for this task - using interrupt

 

[Tahmid]

And best choice for this task - using interrupt

          i++; TMR1IF = 0;
                   if (i == N) {                                // where N - time as a multiple of 524,288 ms
                     PIN_A1 = !PIN_A1; 
                     i = 0;
                   }

Moving the above segment to the ISR lets you multitask - do something else while waiting for the timer to overflow. For that, you also need to set the interrupts, so

   INTCON = 0xC0; //GIE = 1, PEIE = 1
   PIE1 = 1; //TMR1IE = 1

This enables the interrupt associated.

Hope this helps.
Tahmid.