At 12:03 PM -0600 12-17-03, Dale Botkin wrote:
>What's between the PIC and the transistor bases?  And which output pins,
>exactly?  And can you post a code snippet, showing how you are setting the
>bits high and low?


There is a 1K resistor between RB.0, RB.1, RB.2, and RB.3 and the
base of a 2N2222 NPN transistor. But RB.4 behaves the same way, and
it's connected to nothing.

Here is the relevant code. At "wait1a" RA.0 goes from a low state to
a floating input-like state, then goes low again at "low".



        include '16F627.inc'
        fuses   _INTRC_OSC_CLKOUT       ;oscillator
        fuses   _WDT_OFF                ;Watchdog timer
        fuses   _CP_OFF         ;Code protect
        fuses   _BODEN_OFF      ;Brownout detect
        fuses   _PWRTE_ON       ;Powerup timer
        fuses   _LVP_OFF        ;low voltage programming
        fuses   _MCLRE_ON       ;MCLR is pulled high internally, RA.5
is available

flash1          equ     RB.0    ;flash output 1
flash2          equ     RB.1    ;flash output 2
flash3          equ     RB.2    ;flash output 3
flash4          equ     RB.3    ;flash output 4

inbit           equ     RB.7    ;input


        org     0

init    clr     RB                      ;set to zero
        clr     RA                      ;set to zero

        setb    RP0
        mov     TRISB,#10000000b
        mov     TRISA,#11111111b
        clrb    RP0

        mov     CMCON,#7                ;comparators off, digital I/O on port A

        clr     maskB                   ;port B mask
        mov     portB,maskB

main    jb      inbit,main              ;stay here until input pulls low

do1     setb    maskB.0                 ;set this flash on
        setb    maskB.4                 ;debug
wait1a  mov     portB, maskB            ;turn on flash
        jnb     inbit,wait1a            ;keep flash on for duration

        ;end of phase 1
        clr     maskB
low     mov     portB, maskB            ;turn off output
        call    ResetTimeout            ;reset timeout counter
wait1b  jnb     inbit,do2               ;if input pulled low, do next phase
        call    CheckTimeout            ;see if I've timed out
        jz      wait1b                  ;jump if not yet
        jmp     main                    ;timed out, wait for next input


--

Bryan Mumford
Santa Barbara, California
http://www.bmumford.com

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu