scan tools

[Peter Gargano]

Shannen Durphey wrote:

> Once upon a time GM issued a tape recorder with an ALDL connector to
> its dealers.  The idea was to drive around with the recorder making a
> record of scanner data, then play it back in the shop with the scanner
> connected. 

So that's why the 160 baud ALDL data stream has a signal 
transition for every bit!  Almost guaranteed to be able
to be recorded by almost any low quality analogue device.

> Would this work with a sound card in a laptop?  How about
> a diacom/wav file interface?

probably, but...

I'm just about to update my simple (single transistor) 160 baud ALDL 
interface (so it works properly on 5 Volt ALDL signals) and update the
software to capture the data into a file. The idea is that you read the 
file created (it will be just ASCII decimal data) into eXcel, and do 
whatever you want. I'll post here when I have it working. Current info 
is still at:

  http://www.techedge.com.au/vehicle/aldl/160/aldl_hw.htm

but the interface needs an extra zener diode and resistor to
work for some (5 Volt data) ALDL data streams. I'd have done it
already but I have to upgrade my ALDL emulator too (see:

  http://www.techedge.com.au/vehicle/aldl/160/aldlemul.htm

but it too needs a slight change).

If you're interested, I need some (more) volunteer testers to
try it out on a real 5 Volt ALDL data stream.

  mailto:peter at mail.techedge.com.au?subject=ALDL_testers

regards,
-- 
Peter Gargano