On Wed, 16 August 2000, Greg Maki wrote:

>
> Jeff Scharpf wrote:
> >
> > I was hoping someone could just take a quick look at a small snippet of code I have and tell me if there is anything obviously wrong. What I'm doing is setting up a 16F876 with porta as input, portb as input, and portc as outputs. I have all inputs for porta and portb tied to V+. I have the portc outputs going to LEDs. All I wanted to do was run timer0 internally, use the timer0 interrupt to go out and increment a register, then display this on the portc outputs to show that the interrupt is working. I used a 256 scaler so it didn't go so fast. I know that i have some defined variables that I have not used yet.I am very new at this :( Any help is greatly appreciated.
> > I did read the beginners help page and was able to run simple code that read an input from port a and incremented a register, then sent it to portc leds. This worked, so I believe electricallly everything is ok.
> >
> > Thanks,
> >
> > Jeff Scharpf
> >
> > Jeffrey Scharpf
> > Senior Engineering Technician
> > Milwaukee Electric Tool Corporation
> > Technical Center
> > Brookfield, Wisconsin, 53005
> > (262) 783-8681
> > _______________________________________________________
> > Are you a Techie? Get Your Free Tech Email Address Now!
> > Many to choose from! Visit http://www.TechEmail.com
> >
> >   ------------------------------------------------------------------------
> >                Name: freq.asm
> >    freq.asm    Type: Plain Text (text/plain)
> >            Encoding: 7bit
>
> snip
>
> > start   bsf     status,rp0      ;set rp0 to set bank1
> >         movlw   0xff            ;set porta to inputs
> >         movwf   trisa
> >         movlw   0xff            ;set portb to inputs
> >         movwf   trisb
> >         movlw   0x00            ;set portc to outputs
> >         movwf   trisc
> >         clrf    portb           ;set all lines on b low
> >         clrf    portc           ;set all lines on c low
> >         bsf     optreg,RBPU     ;release port b internal pullups
> >         bcf     optreg,INTEDG   ;set interrup to occur on falling edge
> >         bcf     optreg,T0CS     ;set tmr0 to perform as timer (internal)
>
> Jeff,
>
> The only thing I see wrong is that your 'clrf portb' and 'clrf portc'
> are actually clearing the trisb and trisc registers since the RP0 bit is
> still set. I hope you have those port pins tied to V+ with some
> resistors!
>
> Try putting the 'bcf STATUS,RP0' command after the 'movwf trisb'
> command. It should work a lot better. And you might want to #include
> <P16F876.INC> instead of having to define all of those registers
> yourself.
>
> Hope this helps,
>
> Greg Maki
>
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Thanks greg that fixed it. Now I have what appears to be an MLAB problem ! :(

Jeff

Jeffrey Scharpf
Senior Engineering Technician
Milwaukee Electric Tool Corporation
Technical Center
Brookfield, Wisconsin, 53005
(262) 783-8681
_______________________________________________________
Are you a Techie? Get Your Free Tech Email Address Now!
Many to choose from! Visit http://www.TechEmail.com

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