At 12:41 PM 8/24/2003 -0700, Bob Axtell wrote:
>Actually, I had, Jinx.
>
>Don'tcha love Morse, though? Interesting how old technology can be used to
>solve a new problem..

This is how I do it on the AVR.
The output is a byte, with wide pulses for a "1" and narrow for zero.
MSB left.
You need a good scope to catch it though, it's rather fast.
Port B pin 6 happens to be free on this processor, so:

Pong:
         push    TEMP            ;Save the input
         push    TEMP2           ;and I need another scratch reg

         cbi     PORTB,6 ;Make sure we start at low
         ldi     TEMP2,9 ;Loop counter

Pong_Loop:
         dec     TEMP2           ;One less to loop
         breq    Pong_Done       ;If zero, we're done

         rol     TEMP            ;Put LSB in carry
         sbi     PORTB,6 ;Otherwise, set and clear
         brcs    Pong_One        ;If zero, nothing to output

Pong_Zero:
         cbi     PORTB,6 ;a narrow bit is a zero
         nop                     ;Keep the zeroes and ones the same total size
         nop                     ;so that the stream dosen't jitter with
         nop                     ;changing data
         rjmp    Pong_Loop       ;and do it again

Pong_One:
         nop                     ;A wide bit is a one
         nop                     ;This expands the bit
         cbi     PORTB,6 ;
         rjmp    Pong_Loop       ;and do it again

Pong_Done:
         pop     TEMP2           ;Restore
         pop     TEMP            ;
         and     TEMP,TEMP       ;restore zero flag
         ret

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