[ILUG] Reverse engineering serial protocol
Kieran.Tully AT acm.org
kieran.tully at gmail.com
Fri Oct 1 11:42:23 IST 2004
On Fri, 1 Oct 2004 10:47:26 +0100, Dale Dunlea <daledunlea at commergy.com> wrote:
> > Without a scope, there's not much you can do to detect baud
> > rate other than "suck it and see". However, if your rx baud
> > rate is too low, you'll just see gibberish; if it's too high,
> > you'll see bits repeated in what you receive (for example,
> > you'll never get a byte that reads 01010101 in binary, but
> > you could well get one that reads 0011001 or 00001111).
> Well, that means I definitely don't have it set too high as I always get
> a single-bit transition on the last byte of a transaction. That's good
> to know.
Expands on the heuristic Christian mentioned.
I remember writing something similar in assembler in college - fun!
> I tried placing a software spy on the windows machine but none of them
> seem to get in at boot time before the driver device locks the port.
Once you know the serial settings, maybe put a Linux machine with twin
serial ports between Windows and the touchscreen and write or find
something on Linux to log and forward the data (avoids need to makeup
Kieran Tully, Software Developer and Tenor
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