Low cost USB ALDL cable

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cmaje72
Posts: 26
Joined: Thu May 27, 2010 4:45 am

Low cost USB ALDL cable

Post by cmaje72 » Mon Apr 18, 2011 5:40 am

Thought I would share this. I just went USB with my ALDL cable trying to figure out some logging problems I was having.
I ordered up one of these:
http://www.superdroidrobots.com/shop/it ... temid=1173

Tied TX/RX (1&2 connections) to the ALDL signal and ground (5 connection).
Download the drivers from the FTDI site:
http://www.ftdichip.com/Drivers/VCP.htm

Install them before you plug it in. Plug it in. Change TP to whatever com port it installed at.

Now as a disclaimer:
I have not tried this with any ECU other than the one I have for my 93 LT1 (16159278). It is an 8192 baud ECU and it worked right out of the box. When I get a chance I am going to test it out on a friend's truck that has a 160 baud TBI ECU (1227747).

robertisaar
Author of Defs
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Location: Camden, MI

Post by robertisaar » Mon Apr 18, 2011 3:20 pm

neat find.... what kind of sample rates are you getting, and have there been any stream glitches?

cmaje72
Posts: 26
Joined: Thu May 27, 2010 4:45 am

Post by cmaje72 » Wed Apr 20, 2011 4:18 am

The sample rate is bouncing around between about 8.3 and 10. Is it supposed to do that or remain steady? It did that with my previous serial cable too. The stream is nice and clean.

With this cable I was able to reduce the wait for silence in my monitor command down to 7ms. Any lower and there are a lot of glitches. With my serial cable the best I could do was 14ms. So it seems to work a little better.

robertisaar
Author of Defs
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Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Wed Apr 20, 2011 4:49 am

AFAIK, the "bouncing" is normal, it's done that with all of my cables....

was your serial cable based on a 2 transistor design, or MAX232? i've found that the 2 transistor needs a lot more pause time than a MAX232 design. i currently don't run any type of pause with my MAX232 converted to USB via a Parallax 28030, but when i had my 2 transistor, i had around ~20mS pauses and still had errors...

cmaje72
Posts: 26
Joined: Thu May 27, 2010 4:45 am

Post by cmaje72 » Wed Apr 20, 2011 9:26 am

My other cable was a diy 2 transistor cable. I'm pretty happy with this one though. Now I don't have to haul the docking station out when I want to datalog.

cmaje72
Posts: 26
Joined: Thu May 27, 2010 4:45 am

Post by cmaje72 » Wed Apr 27, 2011 5:03 am

Another small update to this. I found some settings in device manager for the drivers for this USB converter. Under advanced there is a setting for latency. By default it was set at 16. I changed it to 1 and was able to completly remove the wait for silence pause in my monitor macro.

Sampling frequency now bounces between 9.5 and 11.8.

robertisaar
Author of Defs
Posts: 962
Joined: Sat Feb 21, 2009 3:18 pm
Location: Camden, MI

Post by robertisaar » Wed Apr 27, 2011 5:13 am

interesting....

and no strange values that pop up randomly yet?

cmaje72
Posts: 26
Joined: Thu May 27, 2010 4:45 am

Post by cmaje72 » Wed Apr 27, 2011 9:44 am

Not that I saw this morning on the ride in but I have not checked the whole log yet,

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