Powering an arduino board using batteries via the the barrel connector, is it ok to use the negative terminal as ground wherever its needed?
For example, I have a shield that takes +5 and Ground from arduino pins – is it ok to use the negative from the battery as the Ground?
UPDATE: I attach a rough sketch. I've ignored control lines etc. The M is for a motor that is being controlled by the H-Bridge which requires +5/GND from arduino and external power.
Best Answer
I'd wire the set-up like this: -
Ground (pin 8 typically for an L298 but will be different on other devices) on the H bridge becomes the star point for the connections to the rest of the "system". This means that motor load currents are kept away from the arduino - these can cause problems. Also keep the wires to the motor battery and to the motor as short as you can to avoid induction into other circuits.