ALDL info

[Mark Glicksman]

Todd King wrote:
> 
>   <<<
>   Hey Todd,
>        I'm not so sure about that, my reasoning is that I have a parallel to
>   serial converter which can transmitt at 110, 150, 300, 1200, 2400, 4800,
>                  Mark Glicksman
>   >>>
> 
>   Not too sure about what? I'm not worrying really about the baud rate
>   "problem", I'm saying that the GM ALDL data stream is pulsewidth modulated.
>   The baud rate mismatch doesn't really apply here since to read the stream as
>   RS 232 is the "wrong" approach anyway! The PWM technique offers tremendous
>   noise immunity over voltage level encoding and is why it was chosen. BTW once
>   you build your PWM demodulator (be it a SW or HW solution; either way it's
>   really easy...) and start reading data you'll find that some of the data
>   fields and locations in the stream are similar (like rpm, etc) between the
>   various cars. You can probably reverse engineer most of 'em, especially now
>   that Mr Ravet has kindly provided the bit-level protocol...
> 
>   Todd

Hey Todd,

	Thank you for the additional information, I will definetly come in
handy.  In the meantime I should have this thing built by the end of the
month.  Hopefully I will be able to read one of these darm computers :)

			VTY
			Mark Glicksman
			mglicksm at suffolk.lib.ny.us