Hi all,

after reading a thread about using a F84 as SPI frontend, I wanted to
roll such a thing my own. as I'm very new to PICs, it is not easy for me
to figure out, where the problem lies in my code. Could anyone help me?
The SPI frontend is just a small part of our robot project containing a
68HC812A4 with 1 Mbyte RAM and 1 Mbyte FLASH, so I'm not willing to
spend days on this problem (and I did spend a week so far...).

Here is the code:

;***** VARIABLE DEFINITIONS
ScratchPadRam   EQU     0x20

a               EQU     ScratchPadRam+0
byte            EQU     ScratchPadRam+1
;**********************************************************************
                ORG     0x000             ; processor reset vector
                goto    main              ; go to beginning of program

main

        bsf STATUS,5            ; Set I/O
        movlw 0                 ; Set all pins to outputs (conserve power)
        movwf TRISA
        movwf TRISB
        bsf TRISA,2             ; Set PA1 and PA2 as inputs
        bsf TRISA,1
        CLRF    PORTB
start   MOVLW   8
        MOVWF   a
looping BTFSS   PORTA,2         ;Skip if Set
        GOTO    looping
        BTFSC   PORTA,1         ;Skip if Clear
        BSF     byte,0
        RLF     byte,1          ;Rotate Left

wait    BTFSC   PORTA,2         ;Skip if Clear
        GOTO    wait
        DECFSZ  a,1             ;Decr a, skip if 0
        GOTO    looping
        BSF     PORTA,3
        BCF     PORTA,3
        MOVF    byte,0
        MOVWF   PORTB           ;write received byte to PORTB
        CLRF    byte

        GOTO start

CU, by Seb im Web