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I need a help with this question. I'm trying to make a Wheatstone Bridge with Arduino, the main idea is read the two legs of the circuit with two analog inputs of Arduino, for the while I'm analyzing the values with 4 equal resistors as the Arduino reads (0 to 1023 bits). The problem is when I change one of the resistors (Rx), the voltage on A0 (first leg C) should not be changed, but it happens.

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I've read something about the analog inputs of the Arduino suffer interference, but I don't know how to avoid this.

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migrated from stackoverflow.com May 8 at 20:20

This question came from our site for professional and enthusiast programmers.
    
You can try taking the reading twice and discarding the first one. However, if you want precision, rather than subtracting two single-ended readings, you should take one differential reading. The ACD of the Mega has this capability, with up to 200× gain. –  Edgar Bonet Jun 4 at 9:02
    
@EdgarBonet - are you referring to the Analog Comparator here? –  Nick Gammon Aug 24 at 6:48
    
@NickGammon: No, I am referring to the ADC of the ATmega2560, which can operate in differential mode. –  Edgar Bonet Aug 24 at 19:36

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