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Unread 04-03-2011, 10:15
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Tom Line Tom Line is offline
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FRC #1718 (The Fighting Pi)
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Join Date: Jan 2007
Rookie Year: 1999
Location: Armada, Michigan
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Moving Crio Modules out of the Crio.

Ok, here's a fun one for those who are knowledgeable about the inner workings of the Crio.

A week or so ago we had an interference fit on some parts on the robot, and wanted to move the modules around in the Crio. Of course, in a couple cases you can't really move them, so we jumped to another option we thought would be workable.

We picked up a couple dB15 connectors, and soldered together a 2 foot jumper cable. We tested this out with both an ohm-meter, then ran current and checked with an am-meter to insure that none of the soldered connections were shorted or close to shorted. It checked out perfectly. We used twisted pair cat6 cable to reduce any possible noise.

However, upon unplugging the analog crio module from the crio and placing the jumper between the crio and the analog module to connect the two, the analog module stopped returning battery voltage (or any other measurement for that matter).

Does the Crio or the analog module look for a specific resistance before they start talking to eachother? Is there some other hardware reason (perhaps intentional) that you cannot do this?

We even 'guessed' that perhaps the outside housing on the db15 was another ground, so we soldered a wire from one housing to the other - that didn't change anything.

Thoughts?
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