I have two sides of an arduino...one is the sensor side running into analog. It connects to the ground on the analog side of the arduino, but the sensor doesn`t run off of the arduino power -- it runs of another appliance at plus/minus 5 volts. this sensor in turn (by the internal coding) can turn a digital output pin to (HIGH) which sends a 5 volt signal out to another circuit, this 5 volts will return to the ground pin on the digital side to complete the circuit. My question is -- are these two grounds differentiated in some way? If not, will these two voltage sources running to the same arduino ground cause some strange things to happen?
stupid question. measured with multimeter - question answered.
My question is – are these two grounds differentiated in some way?
Ultimately the analogue and digital grounds are at the same potential. However in order to prevent noise being injected from the digital side to the analogue side all analogue sources should be connected to the analogue ground and only connected to the digital side at one point. This is done on the PCB. When laying out a PCB for low noise operation this should be done with a so called stared ground.