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Topic: Connecting 5 V to pin? (Read 655 times) previous topic - next topic

yen

#5
Sep 01, 2011, 04:33 am Last Edit: Sep 01, 2011, 04:46 am by yen Reason: 1
The risk in inversely proportional to your knowledge of electronics and the AVR microprocessor chip.

True; but trusting the controller to work as expected is yet another topic imho XD. And I tend not to trust the software that much in this case since I neither read the bootloader-code nor did I read the whole datasheet...  ;)

You should never use a multimeter to measure resistance if power is applied to a circuit.

Sure, but if I remove power from the controller, I'll probably get even worse results... And the resulting - distorted - value should only be lower than the real one, shouldn't it? So if I get a very high resistance-value, shouldn't there be a pretty good chance that the input-resistance really is high? (Sure, there are cases where this won't apply, especially when it comes to AC/alternating signals in common...)
Edit: Oh, and of course, when the pin is set as output, the measure will also be "a bit crazy"  :D

Grumpy_Mike

Quote
So if I get a very high resistance-value, shouldn't there be a pretty good chance that the input-resistance really is high?

No.

A meter is a source of current, it tries to force it round a circuit. Using this to measure a circuit with voltage in it already can damage the meter or even the circuit. At best this practice is totally meaningless, at worst it is damaging.

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