Any Simple ASM interupt code examples out there?

[George]

Am looking for a simple interupt code example that will just escape to the interupt on rollover of tmr. I need to have a reliable timebase for a program I've got where it needs to exit with an ASM interupt.

Thanks in advance

[ronjodu]

Let me be the first to point you here.......
http://www.picbasic.co.uk/forum/showthread.php?t=3251
It has to be simple, even I can use it.

Hope it helps.

[skimask]

Am looking for a simple interupt code example that will just escape to the interupt on rollover of tmr. I need to have a reliable timebase for a program I've got where it needs to exit with an ASM interupt.

Thanks in advance

Section 9.3 of the PBP manual, just set up your timer module, change the references from portb.0 over to the timer, and you're set...

[mister_e]

Now we have 3 version of interrupts here

ASM
Instant Interrupt
PBP ON interrupt

the easiests are PBP, and Darrel Instant interrupts. More efficient pure ASM... but Darrel's instant is really f**** close of the ASM.

As always, nobody's give the PIC # and the expected results... hard to point out the best and ultimate Solution.... it won't break your keyboard to type few more lines. If so, i'll send you a brand new one... i buy keyboard in slap of 100's. 1-2 buck each.

[George]

The PIC is a 16F676 so it's pretty tight with code space and variables (have tried DT's code but it runs out of variables), I'm just trying to exit from a serin command where there is always noise coming into the port (AM reciever module) just to increment a timer - and turn device off after a predetermined time.

[mister_e]

Can you post your code here?

To me a PIC with a USART would be more interesting in this case.

[sougata]

Hi,

Even if you are not using interrupts the timer0 rollover (INTCON.2, T0IF) gets set. So you can periodically check if the flag is set. To get proper timeout your main body loop should not execute for more than the timer0 rollover period. Even if it does then you miss a few ticks but still get some dirty timing. So here is how it goes

    OPTION_REG = %11000111     ' SET PRESCALE HERE 256 (Datasheet PAGE 14)
    ' @4MHz AND PRESCALE TIMER0 ROLLSOVER IN ABOUT 65.5 mS
    TIME_COUNTER VAR WORD      ' MAY BE A BYTE ALSO
    
    INTCON = 0
    TIME_COUNTER = 0
    MAIN_LOOP:
    
    ' DO WHATEVER
    IF INTCON.2 = 1 THEN       ' CHECK IF TIMER ROLLED OVER
       INTCON.2 = 0            ' CLEAR THE HARDWARE FLAG
       TMR0     = 0            ' CLEAR TIMER0 IF YOU WISH
       TIME_COUNTER = TIME_COUNTER + 1 ' INCREMENT YOUR COUNTER
    ENDIF
       IF TIME_COUNTER > PRESET THEN QUIT_LOOP
       

    GOTO MAIN_LOOP
       
    QUIT_LOOP:
    
    ' TIME OVER DO WHATEVER

PRESET is hard coded. In your main routine when you receive a valid signal don't forget to clear (Reset) the timer_counter variable and any pending ticks i.e., INTCON.2
Hope this helps