On Friday, March 16, 2007 6:06 PM [GMT-3=CET],
Harold Hallikainen  wrote:

> > On Friday, March 16, 2007 3:11 PM [GMT-3=CET],
> > wouter van ooijen  wrote:
> >
> > > > The start bit idea is clever! It allows a character to have
> > > > up to 7 dits
> > > > or dahs. You still have to count the bits as they go out (or
> > > > are thrown
> > > > out), though since an all dit character would go to zero as
> > > > soon as you
> > > > throw out the start bit.
> > >
> > > Wouldn't a stop bit be easier? Shift, if result in register is 0 you
are
> > > done, else you transmit what is in the carry and shift again.
> > >
> > > Wouter van Ooijen
> >
> > Nice Wouter!
> > It might be necessary to clean up the carry flag before shifting, isn't
> > it?
> > Also is better to use "1" for dots than for dashes. Doing so, you can
send
> > the error sign.
> >
> >       bsf     STATUS,RP0
> >       movlw   B'11111111' ; Error sign
> >       movwf   BytesRx
> >
> > mCODE
> >       BCF     STATUS,C ;do not shift "ones" now
> >       movlw   0
> >       RLF     BytesRx,F
> >       XORWF   BytesRx,W
> >       BTFSC   STATUS,Z
> >       GOTO    end_of_char
> >       btfsc   STATUS,C
> >       goto    DASH
> > DOT                     ; any output routine e.g.
> >       bsf     PORTB,7
> >       ;(delay intra-elem + 1 element)
> >       bcf     PORTB,7;
> >       GOTO    mCODE
> > DASH  NOP
> >       bsf     PORTB,7
> >       ;(delay intra-elem + 3 element)
> >       bcf     PORTB,7;
> >       GOTO    mCODE
> > end_of_char
> >       ;(end of char delay inter-char-elem + 3 element ???)
> >
> >
> > Dennis.
> >
>
>
> I don't think you need to clear the carry first. Also, you can test for
> zero by moving a byte of ram to itself. Your code becomes...
>
>
>        movlw   B'11111111' ; Error sign
>        call    SendMorseChar
>
> SendMorseChar
>   cblock
>        MorseChar
>   endc
>        movwf MorseChar    ; Save character for shifting
> SendMorseCharA
>        RLF   MorseChar,f  ; shift msb into carry
>        movf  MorseChar,f  ; test to see if we're done
>        bz    SendMorseCharZ ; We're done, get out
>        skpc               ; skip if dit
>        call  DoDah        ; go send dah - PRESERVE CARRY!
>        skpnc
>        call  DoDit        ; go send dit
>        call  InterCharDelay
>        goto  SendMorseCharA ; go send next bit, if any
> SendMorseCharZ
>        return              ; we're outta here!
>
>
>
> Harold
>

Harold,
I don't see it.
If C is not clear, a "one" is pushed right-to-left into the register,
or the previous logical state. So SendMorseCharZ label is never
reached....
The only way to get "zeroed" MorseChar, is by rotating zeros!... I'm
correct?


Regards,
Dennis.

Ps: Now it is a PIC issue. It's OK James? more chances to wake up Scott,
Andrew and company :)






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