TMR1 wont work correctly

BGAmodz · Feb 14, 2014

Hi all .

I don't know whats wrong with my program , it is for a simple led blinking with a delay of 5 seconds .
The led turns on after 5 seconds but wont turn off after another delay .

This is the program script :

Code:

int time = 0;

void interrupt () {

  if (TMR1IF_bit ) {

  TMR1H = 0x0B ;
  TMR1L = 0xDB ;

  time++ ;

}
  PIR1.TMR1IF = 0;
}
  void main() {

T1CON = 0x39 ;
INTCON = 0xC0 ;
TMR1IE_bit = 1 ;
TMR1IF_bit = 0 ;
TMR1H = 0x0B ;
TMR1L = 0xDB ;
TRISA = 0x00 ;
PORTA = 0 ;

  while(1) {
  if ( time == 10) {
  porta = ~porta ;
  time=0;

  }
}
}

Ian Rogers · Feb 14, 2014

Have you copied that code or re-written it.... It won't compile like that... porta is in lower case..

If you can simulate, check the PORTA = ~PORTA; operation to make sure it's doing what you want!!

BGAmodz · Feb 14, 2014

Ian Rogers said:
Have you copied that code or re-written it.... It won't compile like that... porta is in lower case..

If you can simulate, check the PORTA = ~PORTA; operation to make sure it's doing what you want!!

yes its written by me and it is compiling , but when i simulate it , the led wont react as it should be ; blinking , it only lights up after 5 seconds and stays like that .

The PORTA = ~PORTA; is working since the initial state of the led is 0 , and after the delay is passed it changes its state to 1

Joe G · Feb 14, 2014

I don't know what sim, lang or chip, but try: LATA = ~LATA instead of PORTA = ~PORTA

Joe G · Feb 14, 2014

also wouldn't something like these work better :
TRISCbits.TRISC7 = 1;
PIE1bits.TMR1IE = 1;
PIE4bits.CCP4IE = 1;

then:
TMR1IE_bit = 1 ;
TMR1IF_bit = 0 ;

BGAmodz · Feb 14, 2014

Joe G said:
I don't know what sim, lang or chip, but try: LATA = ~LATA instead of PORTA = ~PORTA

Currently using pic16f876A

Joe G · Feb 14, 2014

must be hi-tech language, I don't know that one....

Ian Rogers · Feb 14, 2014

If you have a shadow register "leds" and use it.. it works

C:

    while(1) {
        if ( time == 10) {
            leds = ~leds ;
            PORTA = leds;
            time=0;
        }

I don't think the ~ operator works very well with ports..

BGAmodz · Feb 14, 2014

Hi Ian roger , i have replaced porta.b0 by led but that didnt make any difference .

I have another program using timer 0 and its working fine , thats really weird .

Code:

int counter=0;

void interrupt () {

if(intcon.t0if==1){
counter++;
TMR0=100;
}
intcon.t0if=0;
}

void main() {

porta=0x00;
Trisa=0x00;
option_reg=0x86;
intcon=0xA0;
TMR0=100;

while(1){

if(counter==313){
porta=~porta;
counter=0;
}
}
}

Ian Rogers · Feb 14, 2014

What compiler are you using???

BGAmodz · Feb 14, 2014

Ian Rogers said:
What compiler are you using???

MiKro c pro 5.61 trial version

Pommie · Feb 14, 2014

You need to turn off the analog function, all analog pins read as zero so complementing wont work. Try adding adcon1=6.

Mike.

Ian Rogers · Feb 15, 2014

Pass.... I can't see how the timer can effect the loading of a port... Just work round it!!!

Ian Rogers · Feb 15, 2014

here was my example.... I use XC8 so I mad subtle changes..

As you can see I also made PORTA digital.... Although when I did, it still didn't work until I made a shadow register.

C:

#include<xc.h>
int time=0;

void interrupt ISR () {

  if (TMR1IF) {

    TMR1H = 0x0B ;
    TMR1L = 0xDB ;
    time++ ;
    }
  TMR1IF = 0;
}

void main() {
    unsigned char leds;
    T1CON = 0x39 ;
    INTCON = 0xC0 ;
    TMR1IE = 1 ;
    TMR1IF = 0 ;
    TMR1H = 0x0B ;
    TMR1L = 0xDB ;
    TRISA = 0x00 ;
    ADCON1 = 0x7;
    leds = 0 ;

    while(1) {
        if ( time == 10) {
            leds = ~leds ;
            PORTA = leds;
            time=0;
        }
    }
}

Pommie · Feb 15, 2014

Ian Rogers said:
Pass.... I can't see how the timer can effect the loading of a port... Just work round it!!!

Any pins that are analog read as zero and so porta=~porta results in 0xff being written every time.

Mike.

Ian Rogers · Feb 15, 2014

Any pins that are analog read as zero and so porta=~porta results in 0xff being written every time.

Yes I get that. But even when they were digital PORTA still returned wrong...

BGAmodz · Feb 15, 2014

Thanks guys i have solved the problem by implementing ADCON1 configuration.

But the question is why ADCON1 is necessary for the pins to work correctly , ADCON1 only got 3 programmable bits .

and by using 0x07 as ADCON1 value we are assigning value 1 to 3 bits that have no use on that register , only usable ones are the ones bellow and are all set to 0 i dont see how this register could affect the pins operations :

ADFM - A/D Result Format Select bit
1 - Conversion result is right justified. Six most significant bits of the ADRESH are not
used.
0 - Conversion result is left justified. Six least significant bits of the ADRESL are not
used.
VCFG1 - Voltage Reference bitselects negative voltage reference source needed for the
operation of A/D converter.
1 - Negative voltage reference is applied to the Vref- pin.
0 - Power supply voltage Vss is used as negative voltage reference source.
VCFG0 - Voltage Reference bitselects positive voltage reference source needed for the
operation of A/D converter.
1 - Positive voltage reference is applied to the Vref+ pin.
0 - Power supply voltage Vdd is used as positive voltage reference source.

Ian Rogers · Feb 15, 2014

BGAmodz said:
Thanks guys i have solved the problem by implementing ADCON1 configuration

I better check mine again then.....

5uco · Feb 15, 2014

BGAmodz said:
Thanks guys i have solved the problem by implementing ADCON1 configuration.

But the question is why ADCON1 is necessary for the pins to work correctly , ADCON1 only got 3 programmable bits .

and by using 0x07 as ADCON1 value we are assigning value 1 to 3 bits that have no use on that register , only usable ones are the ones bellow and are all set to 0 i dont see how this register could affect the pins operations :

ADFM - A/D Result Format Select bit
1 - Conversion result is right justified. Six most significant bits of the ADRESH are not
used.
0 - Conversion result is left justified. Six least significant bits of the ADRESL are not
used.
VCFG1 - Voltage Reference bitselects negative voltage reference source needed for the
operation of A/D converter.
1 - Negative voltage reference is applied to the Vref- pin.
0 - Power supply voltage Vss is used as negative voltage reference source.
VCFG0 - Voltage Reference bitselects positive voltage reference source needed for the
operation of A/D converter.
1 - Positive voltage reference is applied to the Vref+ pin.
0 - Power supply voltage Vdd is used as positive voltage reference source.

This seems to be from the 16F88x (or similar) data sheet, not from the 16F87x ??

Dave

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