I sent this messsage earlier today from my machine at work and think I
used the wrong address, dammm machine:-(


Hi all,

Hope this gets through only I'm not using my normal PC base!

Having some problems, code I think with a 16C64 and port B.

The code snippets below show 'A the initialisation of the ports and 'B
the code to talk to the port. The idea is that at the start of the prog,
data from some BCD switches is read into the pic.

The problem is that whilst the pulses and port A are working correctly,
port B aint. It seams to be sitting high, 5v. 10k's pulling it down only
take the voltage down to about 1.4v, thus any lines high from the BCD
switches are not distinguishable from the others and the value read from
the port is always FF. If I completely ground the lines from the port
this has no effect other than the pic seems to ignore any value from
this port. When the lines are grounded, a current of about 160uA is
flowing through them.

What have I forgotten or got wrong?

Code A
init    clrf    porta           ; clear port
        clrf    portb           ; clear port
        clrf    portc           ; clear port
        clrf    portd           ; clear port
        clrf    porte           ; clear port
        bsf     pa1             ; selected page 1
        movlw   b'00000101'     ; set initialisation of rtcc
        movwf   optreg          ; load option reg with prescale of 64
        movlw   b'1111'         ; set port a i/o
        movwf   trisa           ; set the ddr
        movlw   b'11111111'     ; set port b i/o
        movwf   trisb           ; set the ddr
        movlw   b'00000000'     ; set port c i/o
        movwf   trisc           ; set the ddr
        movlw   b'00000000'     ; set port d i/o
        movwf   trisd           ; set the ddr
        clrf    trise           ; set port e i/o

        bcf     pa1             ; selected page 0

        call    clearreg        ; subroutine to clear all registers
        call    bcdget          ; subroutine to get bcd switch settings
        movlw   .100            ; put initial value in rtcc
        movwf   rtcc
        movlw   b'10100000'     ; enable global & rtcc interrupts
        movwf   intcon

Code B

bcdget  clrf    porte           ; start with a clear port
        bsf     switch12        ; turn on switch 1+2 power
        call    delay1          ; allow time for port voltage to settle
        movfw   portb           ; get switch settings
        movwf   r0              ; and put into reg
        bcf     switch12        ; turn off switch 1
        nop
        bsf     switch34        ; turn on switch 3+4 power
        call    delay1
        movfw   portb
        movwf   r1
        bcf     switch34
        nop                     ; end sub
        return
--
Philip Martin   email philip@philmart.demon.co.uk

Royal Quays, North Shields.

--
Philip Martin   email philip@philmart.demon.co.uk
Royal Quays, North Shields