I have Arduino Uno connected to a computer with a USB cable. Then I have a DC circuit, powered by a wall adapter.
In this circuit, I have a shunt resistor (connected in series after the load) and I would like to measure the voltage across it with the Arduino analog pin.
But I am unsure if, or how this will work. Since the computer and the circuit have separate power sources, then their grounds aren't common. Does that mean it won't work? I am too afraid to connect the grounds because I am scared of frying my PC.