128838 ANFK ECM infos????

[Peter Gargano]

Volker wrote:
> 
> -----BEGIN PGP SIGNED MESSAGE-----

Any chance of getting rid of this PGP rubbish when you post?
(and perhaps editing out the non-relevant parts of your quoted text?)

> Any idea how the PROM-ID might look like on the serial stream? I have
> to guess the interface parameters first (again, I don't know if it's a
> 160 or 8192 baud interface)

If you get unsolicited comms from the ECU then it's going to be
8192, if you need a 10k resistor across the DIAG terminals on
the ALDL connector to get anything, then it may be either. If
you get some sort of consistent display with my 160 baud display
hardware/software then it'll be 160 baud....

>  and I need to have at least a few known
> bytes to identify the correct settings (the PROM ID should be the only
> non-variable data at the stream, right?). As soon as I've got it, the
> next step will be to interpret the data.

If you really get stuck, there are a few disassemblers out there
that will allow you to fairly quickly work out what the processor
is doing (or not doing) with UART interrupts. 

  see   http://www.techedge.com.au/utils/default.htm
 
> Yesterday I tried to catch data (I assembled an interface converter
> using some information off the net) and with 160 baud the data stream
> looks best. Every two seconds or so there is a data packet but with
> unequal size (sometimes 32 byte sometimes 33 byte).

The original 160 baud software I wrote seems more prone to noise than
my latest (vers. 1.5A) software - get my newer software and connect the
vehicle's ALDL data line to the PC's Rx line (via the converter), rather
than to the PC's CTS line as suggested. I'm always interested in feedback
on how these interfaces work - both good and bad feedback.

Sounds like you're seeing 160 baud, but with some noise. What is the
smallest regularly repeating packet size -  18 to 22 bytes? 
Did you see your vehicle/ECM in Dan's 160 baud ECM stuff (thanks Dan):

  http://www.isthq.com/~dan/aldl.htm

> I found no similar
> bytes so I guess the parameters must have been wrong (160N81) or my
> fresh assembled interface is buggy (or anything else).

My simple 160 baud software does no byte interpretation, just shows
raw GM ALDL data, at 160 baud. With no noise you should see a fairly
constant display with values changing slowly. Don't forget to try it with
the motor OFF first, as this will give you a fairly noise free environment.
If the display "breaks up" with the motor ON, then it's noise ...

Peter.
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