hi'
I wrote program for 0-99 counter. but i don't know why interrupt not work. TMR0 never incremented and then interrupt not accure. tell me, where is my problem, and how can i run Timer0, please? my compiler is microC.

C code:

#define uchar unsigned char

//-----Function Prototype--------
void inith();
void first();
void second();

//----Variable Dicleration-------
uchar num[10]={0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x07,0x7F,0x6 F};
uchar j, hop; // j for second function and hop for switch

//----Interrupt routin-----------
void interrupt() {
TMR0=0;
INTCON=0xa0; // clear timer0 interrupt flag bit
if(j!=0) ~hop; // function hopping (first and second function)
}

//-------------------------------
//----Program Starts Here--------
void main(){

inith();

for( ;; ){
if(!hop)
first();
if(hop)
second();
}
}

void first(){
uchar i, d;

portb.F2=0;
portb.F6=1;
for(i=0;i<10;i++){
portd=num[i];
if(i==9){
j++;
if(j>9) j=0;
}
for(d=0;d<100;d++){ // 1's Delay
delay_ms(10);
if(hop) break;
}
if(hop) break;
}
}

void second(){
uchar i;

portb.F6=0;
portb.F2=1;
portd=num[j];
for(i=0;i<5;i++){ // 1's Delay
delay_ms(10);
if(hop) break;
}
}

void inith(){

portb=0x00;
trisb=0x01;

portd=0x00;
trisd=0x00;

hop=0;
TMR0=0;

OPTION_REG=0x01; // PSA = Timer , 1:4
INTCON=0xa0 ; // Global Interrupt enable
}

 

It has been a while since I did C and not yet on a PIC but it looks like your interrupt routine makes TMR0=0 on every interrupt so it will never increment.

__________________
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Beware the asterisk *

 

thank you ClydeCrashKop,
but TMR0 is a register and i can write it. when i change contents of this (for example TMR0=96; ), i have this problem too.

 

I don't do C either, but TMR0 is the poorest of the available timers, and has a LOT of restrictions.

__________________
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http://www.winpicprog.co.uk

 

yes you are right Nigel.
this program is correct when i use Timer1. timer1 has a TMR1ON for control of stop and start. but timer0 has not this control bit and i don't know how can i run timer0.

 

Which PIC are you using? Why not use Timer1 if it works?

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com/

 

Thx blueroomelectronics.
I used PIC 16F877A.
becuse i can not run and work with this timer. and i didn't see anybody can work with this timer.

 

Timer0 works fine, it's a simple 8bit timer. Timer 1 & 2 are part of the 16F877A.
Timer0 is always running. Tough to turn off actually , use the MPLAB simulator and set the T0CS to FOSC/4

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com/