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> From: <Nichole Petty> <PHXSYS@AOL.COM>
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: Still got the serial blues!
> Date: Tuesday, June 09, 1998 11:39 AM
>
> In a message dated 98-06-09 05:05:39 EDT, you write:
>
> << >EMITBIT
>  >        DECFSZ  STIME,F
>  >        GOTO    W4              ;BAUD DELAY
>  >        RRF     INDF            ;SHIFT RT
>  >        DECFSZ  SCOUNT          ;BIT COUNTER
>  >        GOTO    SEND_BITS       ;SEND MORE BITS
>  ***look here>        RRF     INDF            ;8 BITS SENT- SHIFT TO ORIGINAL
>  >        MOVLW   BITTIME
>  >        MOVWF   STIME           ;LOAD BUAD DELAY
>  >        MOVLW   STOPBIT         ; SEND STOP
>  >        MOVWF   SSTATE
>  >;       BCF     _SEROUT         ;START BIT INVERTED
>  >        BSF     _SEROUT         ;START BIT NON-INVERTED
>  >        NOP
>  >        RETURN
>  > >>
>
> >If you are not reloading the BUFFER data, then the data will be rotated, but
> >out by one bit. Does this help?
>
> I discovered one of my problems. I don't need the second RRF. The data was
> previously shifted to the original position with the previous RRF. When I
only
> run the serial out routine everything works, but when I  allow the
> multitasking with the PWM, servo and motor, again the first 5 byte loop works
> great but the second is garbage. Something else in the program must be
> corrupting the FSR. I thought I was reloading the buffer. If not what should
I
> change?

Nichole,
Something is probably clobbering the FSR. If this is the case, you need to
keep a local copy of the FSR in another register and swap it back when the
routine is active. By the same token, you MIGHT want to save the FSR
contents before swapping so you can swap the original contents back
before continuing your multitasking! Otherwise the FSR problem will just
migrate over to the other routine. Whenever you multitask, use local
copies of things that might get clobbered.

Hope this helps.
Fr. Tom McGahee