I am building a project that includes an analog Input and several digital Inputs and Outputs. All of them connect to ground in some way. Do I need to worry about voltage, coming from the digital outputs, going to ground, and effecting readings on the analog input? If so, how do I deal with this?

  • If you have a different power supply powering the sensors than the arduino then you should connect all grounds so that they are common. In other words the remote power supply and the arduino's power supple should have common bridged. – Tyson Mar 11 '15 at 0:44

The arduino has build in pull up resistors, it is not a residue voltage coming from ground more than a "not 100% 0 volt" resistor.

Even though there is built in pull-up resistors one can add additional resistance to the arduino to make sure it will not show a false positive.

From what i have learned, you cannot experience voltage comming from ground (if everything is properly wired), if you want to make sure. Place a diod in the direction of the power flow, to prevent this.

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  • In what cases would it not be wired correctly? – Hoytman Mar 9 '15 at 20:48
  • just to give an example out of many but reversed polarity. or 2 circuit where one might have less resistance. – Magic-Mouse Mar 10 '15 at 6:36

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