PIC16F676 troubles

[keithv]

I've tried several things with the registers, but no luck. I've also added a sub to make it behave the way it should:

#config 
    __CONFIG _CP_OFF & _PWRTE_ON & _INTRC_OSC_NOCLKOUT& _MCLRE_OFF
#endconfig

ADCON1 = %00000000
ANSEL = %00000100
CMCON = 0      

TRISA = %11001100
TRISC = %00000000

LED var PORTA.1
PUSHBUTTON var PORTA.3


led = 1
pause 100
led = 0
pause 100  
led = 1
pause 100
led = 0

main:

    if PUSHBUTTON = 0 then 
        toggle LED
        pause 25
        gosub buttonrelease
        pause 25
    endif
    
goto main
end

buttonrelease:

    do until PUSHBUTTON = 1
        pause 10
    loop
    
    return

It still does the same thing. The LED flashes on power up. The button works once. And then it locks up. And I've tried several other "lower level" ways of making the LED toggle instead of the TOGGLE statement. It's always the same. Here's something interesting, though. If I change the code to just make the LED come on when the button is pressed instead of trying to toggle it like so:

main:

       if PUSHBUTTON = 0 then
              LED = 1
       elseif PUSHBUTTON = 1 then
              LED = 0
       endif

goto main
end

Everything works perfectly! So I'm assuming the problem isn't with the MCLR pin or the registries. Do I need to define the oscillator?

[Tabsoft]

I think the issue is the Comparator module is still turned on.

Your CMCON = 0 sets the comparator to Reset with RA0 and RA1 connected to the Comparator module.
Have a look at the DS Figure 6-2 which shows the possible 8 modes of the comparator.
You should try setting CMCON = %00000111

[keithv]

That did the trick. Thanks, Tabsoft!

[Tabsoft]

Good deal.

I suspect with the Comparator module set to 000 whenever you perform a Toggle command this actually reads the port then writes the new value to it. This issue is that the port will always read 0 when it is configured in Reset mode.