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Unread 17-01-2011, 13:03
EricVanWyk EricVanWyk is offline
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Re: I2C Cable Length issue?

I'm putting my vote behind Matt's suggestion. However, just be sure to check that there aren't any shorts between the wires first.

If you have an oscope available, take a look at the wave forms. If they look a bit too curvy (as opposed to square), your RC time constant is too long. You can fix this by reducing C (shortening the cables), or reducing R.

To reduce R (increase pull up strength), the header just behind the NXT connector is a convenient place to do it. Try putting a 2k or 3k resistor in parallel to start. Check the schematic for details.
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