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Topic: Will resistance in digital input circuit cause problems? (Read 317 times) previous topic - next topic


I am monitoring 8 circuits on an Uno board as digital inputs.  7 use internal pullup resisters and 1 uses an external pulldown.  If each circuit I am monitoring has ~2k ohms resistance when closed, will this somehow create a problem or damage the board? (as opposed to monitoring circuits that are ~0 ohms when closed).  Thanks.


As long as the voltage is within spec your fine with the Arduino. But I can't say anything about possible problems the load the Arduino (and pull up/down) may cause. Don't know what "the circuits" are.
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Do they measure <1.5V when low, and >3V when high? Then you'll  be all set.
Look at them as setting up a voltage divider with a 30K internal pullup.
5V*2000/(30000+2000) = 0.3V.  Good!
5V*30000/(2000+3000) = 4.7V. Good!
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