Can't get POT work on P12f675 - Newbie

[berslan]

Come on guys, did I ask such a stupid question that has to be ignored?

[Acetronics2]

Come on guys, did I ask such a stupid question that has to be ignored?

Hi,

Yes and No ...

If you had read your Datasheet ...you could have noticed that GP3 is not a pin like the others ...

BUT, in your favour, you are not to know how "POT" works ...

So, just remember POT needs the pin to turn from time to time into an OUTPUT ...

And this is written nowhere in the manual ...

The Proof :

POTT    movwf   RM1             ; Save bit mask
        call    HIGHT           ; Set pin high to charge cap
        movlw   10              ; Charge cap for 10ms
        call    PAUSE
        movf    RM1, W          ; Get bit mask
        iorwf   INDF, F         ; Set pin to input
        bcf     FSR, 7          ; Point to port
        xorwf   INDF, F         ; Flip bit to low
        clrf    R0              ; Zero counter
        clrf    R0 + 1
potloop bsf     FSR, 7          ; Point to TRIS
        movf    RM1, W          ; Get bit mask
        xorwf   INDF, F         ; Set pin to output
        CLRWDT?NOP		; Discharge a little (& clear Watchdog timer)

Alain

Change pin used ... no other solution ( ... RCTime won't work either )

[mister_e]

To add to Alain's explanation, GP3/MCLR is an input only. But huh... why using POT while your PIC have an ADC converter? Check in your manual and on this forum for ADCIN.

Make sure your pot impedance meet the datasheet requirement (<2.2K if my memory serves me well)

If you're using a Photoresistor, you will need to use a buffer (op-Amp, transistor or else) in between to match the impedance.

[berslan]

Thanks Alain. Now I get it. In fact I already knew that GP3 is input only and without thinking about how pot works, I used GP3 intentionally, since I could not use it as an output if I needed one later. Smart huh?
And mister_e, I will give a try to ADCIN. And will make sure to use a analog available pin. thanks for the guidance.

[berslan]

Just changed the pin, and it works.
Thanks a lot guys, you are good.

[mister_e]

Usually we don't accept anything under "You're the best"... but Just kidding.

Enjoy!