RE: Re: Anyone use the L9637 ISO 9141 Interface chip from ST?

Jeff & Dale-

Thanks for all your feedback. Let me try to answer some of your
counter-questions:

> My memory is fuzzy. Are you sure that 1 and 13 aren't power or
ground?
> My 98 Passat's connector has two grounds and one power, and a K
line.
> My GTI also has an L line. I can look it up later if you like.

I'm certain that I've got the pins correct. If I had them backwards,
then pins 4 and 5 (the grounds) wouldn't match up to holes with pins.
I have tried to include a picture of my S4's port to show you what I
see. If it doesn't show up below, then use this link:

<IMG SRC="http://www.guisoft.com/pics/s4-obdii.jpeg">

> I don't claim to be an expert, but the schematic on my web page
works
> and is probably a good starting point for you. It's mostly a clone
of
> the VWtool interface. In your case, you can use a simpler interface:
> since your car doesn't connect the L line to anything, you can
leave off
> an optoisolator and a few other parts.

I will either use a circuit like that, or the L9637 part. They
basically do the same thing. The optoisolation might be unnecessary
in
my application because I'm looking into powering my hardware from the
battery power on the OBDII connector.

> I'm unclear on what your long-term goal is. Did you want something
you
> would leave running in your car for data logging?

Basically, yes. I want something that on powerup will configure the
port to continuously output one or more variables defined during
initialization. Then, another command from the external hardware
will
cause it to either output other data, or cease.

>I don't know if your S4 is different, but on my car pins 1 and 13
> aren't used. Are you sure you aren't looking at the plug upside
> down?

I don't think so. The pic above should clarify this.

I'm going to keep looking around my S4 resources to see if I can find
out what the pin 1 and 13 are for. In the meantime, I think I will
begin playing with the K line.

Thanks for your suggestions, and I'll keep you posted.

Brian

 
Received on Wed Jul 26 18:08:06 2000