GM Serial Data

[steve ravet]

Ross, have a look at "Fil's home page" at

http://www.repairfaq.org/filipg/

There's a blizard of information there, including lots of parallel and
serial port stuff.  Start/stop bit info is there.  Also, search in the
diy_efi archives for lots of info about reading 8192 ALDL streams. 
Hooking it to your PC is "easy", understanding the data is "hard".

Basically get a MAX 232 level shifter to convert the ALDL voltages to
RS-232.  Then program your computer to as close as 8192 as you can get,
I think a PC gets to 8228 or something like that.

--steve

Ross Myers wrote:
> 
> Hi All,
> 
> So it is that GM uses 8192baud, 1Stop & no Parity for Comms on later PCM's.
> If I am looking at a data stream of this, how can I pick out the start and
> stop bits from a data capture?. I've scanned the net for info on serial
> comms but to no avail.
> 
> Thanks
> 
> Ross Myers

-- 
Steve Ravet
ARM, INC
steve.ravet at arm.com
www.arm.com