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Topic: i2c pull-up resistors: needed or superfluous? (Read 624 times) previous topic - next topic

msx

Aug 19, 2008, 12:08 pm Last Edit: Aug 19, 2008, 12:13 pm by msx Reason: 1
Ok, as i wrote in the previous post i'm trying to use an i2c lcd with arduino diecimila, without success.
One thing i noticed is that, altough it is stated all around that the atmega168 has internal pull-up resistors, almost everybody uses extra external resistors.
So are they needed or not? I would try it but don't have resistors at hand..

(Edit: sorry it was ment for hardware/interfacing)
http://msx80.blogspot.com/

kg4wsv

I had one bus of 4 sensors, total length nearly 3 feet, and did not use external pullups.  It worked no problems.

A particular peripheral, or a bus with lots of peripherals, or a long bus could require external pullups, but in my limited experience I haven't needed them yet.

-j


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