Philip -

Just a shot in the dark... is the EQU statement for 'trisb' pointing
to the right address?

Steve

> Subject:      Port B Problems
> Author:  PC:philip@PHILMART.DEMON.CO.UK at INTERNET-HUSKY
> Date:    19/12/97 08:22
>
> I sent this message 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
>