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Unread 29-03-2010, 04:05
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Danny Diaz Danny Diaz is offline
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Re: I2C Cable Length issue?

Quote:
Originally Posted by ajd View Post
We wanted to put the sensor somewhat farther away from the sidecar than our NXT cables could reach, so we cut an NXT cable in half and soldered PWM-gauge wires across corresponding colors. However, when we plugged it in and rebooted the robot, the cRIO reported that the sensor did not respond when it was asked for its name and manufacturer.

We are fairly certain that our solders are good and that the right cables are soldered together - we used a multimeter to check continuity, etc. Since the wiring is essentially identical to the original cable, the only thing we can think of being a problem is the high cable length interfering with the signal. Has anyone else had any problems with trying to extend NXT cables?
I'm using a different I2C sensor (a compass with tilt compensation) and I am getting the same problem - though I have not yet tried to plug into an NXT since I actually need the 5v from the digital sidecar (and not 4.3v from NXT). I am using the longest NXT cable, with an end cut off and I attached about 3-4 inches of additional PWM cable to break out the power vs the I2C data/clock lines. I am also running into a problem with the cRIO where the device seems to "not respond" when asking for its address and other information. Not sure if it's the exact same problem, but it seems similar. I'm going to look into this further, and let you know what I find - I'd hope it isn't the cable length, I2C is supposed to be able to handle 10 meters of cabling (which I'm nowhere near even 1 meter).

-Danny
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Danny Diaz
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Last edited by Danny Diaz : 29-03-2010 at 04:08. Reason: added info
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