[SOLVED] Tmr0 configuration in Melab PICBASIC PRO

[alokdaga]

Hi,
I am trying to configure Timer0 in PICBASIC PRO. Processor is 16f877a.

I need to generate an interrupt periodically and update seconds counter to ultimately update time.

I don't want to use RTC chip...

Any help in this regards will be highly appreciated..

Regards

 

[MUKESH.K.S]

I think you want to generate an interrupt in every second. For this set timer0 in counter mode with prescaler value 256 to get maximum time delay. Since the micro controller is very fast it will overflow many times within a second depending on your clock speed. You need to calculate how many times the timer will overflow within a second depending on the clock frequency and prescaler value.Then use that value as a count to make exactly one second delay. Example program is given below

#include <htc.h>
#ifndef _XTAL_FREQ
#define _XTAL_FREQ 20000000
#endif
int COUNT=0;

__CONFIG(FOSC_HS & WDTE_OFF& PWRTE_OFF & BOREN_ON &
LVP_OFF & WRT_OFF & DEBUG_OFF & CPD_OFF & CP_OFF);
void interrupt ISR(void)  //interrupt service routine for timer0 overfloe
{
if(TMR0IF)
{
TMR0IE=0;
TMR0IF=0;
COUNT=COUNT++;
if(COUNT==76)
{
SEC=SEC++;
count=0;
}
}
}


void main(void)
{

OPTION_REG=0X07; //timer0 in counter mode with prescaler 256
GIE=1;           //global interrupt enable
PEIE=1;         //peripheral interrupt enable
TMR0IE=0;   //timer0 interrupt enable
while(1);
}

 

[alokdaga]

Thanks ... Was interested in PICBASIC code...