VETTE Communication Problem.

[Richard Wakeling <kojab@ar.com.au>]

Sorry for the double post. My son sent the wrong name of John Smith? I
have also made a few changes to make our problem I hope a little
clearer.

Cheers Richard. TIA

Hey Guys,

Its been a while, but I've got one question for you all.

Okay, I'm currently having a little bit of difficulty with the
communications of the BUA,BUC,AANM chips.

Unlike some other chips (ABTD), the BUA,BUC,AANM are pretty fussy about
getting 8192 communication started..

Here's some facts:

This is how I seem to understand how the Vette communication is supposed

to work.

Through-out this process, there is the normal 10k sitting in the ALDL
plug.

There is a out-going 160 baud message constantly being sent... at the
end of each
transmission, there is 50 ms gap, where the computer waits for a
inbounding 8192 baud
request for high speed transmission.

This transmission is supposed to be:
0x80 Message ID
0x56 Message Length
0x01 Message Mode
0x29 KSUM

Okay...
Once the computer is in that mode, it stays in high speed transmission
until power-down.

For some chips (ABTD), this process works all the time... and I'm not
even
checking for that 50 ms
delay.. so I imagine, due to coincidence it times perfectly once... and
bingo, no problems.

HOWEVER, for the BUA,BUC, and AANM this is not the case.

Okay... here's a couple of ideas... and cases I've ruled out..

Okay, there's nothing to do with the timing of the 10k resistor cutting
in...
Reason: I've bypassed Diacom's resistors circuit, and stuck a 10k
permanently... works perfectly.

What I'm requesting, shouldn't be wrong...
Reason: Once diacom's put it in the high transmission mode, my program
seems to work perfectly.
Also, I've actually monitored Diacom with the computer, and nothing is
getting sent as well as the request.


Okay, so I'm imagining this problem to be associated with timing? Hmm...

I've tried to time it,
and also no success... I'm really stuck on this one guys. Is there some
trick to it?
Maybe its the device I'm using? Not enough voltage or something? Hmm.. I

don't think that's right. All I know, is that it doesn't work.. and I'm
getting pretty frustrated.

Please help me out on this one, coz I wanna get stuff working for the
American cars.

Thanks guys!

Cheers,
Andrew and Richard.




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