Hi Graham,


This code definitely works on my 12C509.

Plonk it into MPASM (or whatever) and compile it. Then program your
chip.
A LED connected to GPIO 1 (pin6) through a 330R resistor to ground
should flash at about a 1/2 second rate when you connect power.

If yours does not work there will be other problems. Verify your chip
after programming and make sure your circuit connections are correct.

If it does work, try integrating some of your code into this, a little
at a time, until you get it all going.

The prescaler setting has been changed to allow the code to detect when
TMR0 = 0. To get a faster flash rate change the value of "LOOP1".


        LIST    P=12C509
        RADIX   DEC
        INCLUDE <P12C509.INC>
        CBLOCK  0X07
          LOOP1
        ENDC
        __CONFIG _CP_OFF & _MCLRE_OFF & _WDT_OFF & _IntRC_OSC

        ORG     0X3FF
        MOVLW   0X80

        ORG     0X0000
        MOVWF   OSCCAL
        GOTO    START


DELAY   MOVF TMR0,w     ; TMR0 must be zero for these instructions if the
loop is to work
        BTFSS STATUS,Z  ; TMR0 must be zero for these instructions if the loop
is to work
        GOTO DELAY      ; TMR0 must be zero for these instructions if the loop
is to work
        DECFSZ LOOP1
        GOTO DELAY
        RETLW 0


START   MOVLW   0       ; set al pins = 0
        MOVWF   GPIO
        MOVLW   0       ; set all pins as outputs
        TRIS    GPIO
        MOVLW B'11010010'       ; TMR0 internal clock, PRESCALER 1:4
        OPTION

FLASH   MOVLW B'00000010'
        XORWF GPIO
        CLRF LOOP1      ; LOOP1 value determines delay. 0 = MAXIMUM
        CALL DELAY
        GOTO FLASH

        END


--
Best regards

Tony

http://www.picnpoke.com
mailto:sales@picnpoke.com