I have a question here, which is probably simple to some of you, but I'm going to ask it anyway.
When using multiple servos from an Arduino, I use an alternative power, to the Arduino's on board power, however Arduino and servo power all derives from the same battery. I also connect the grounds, from the servos to a ground on the Arduino. I assume this to be correct, as it works and all the information I have viewed supports that.
However, if I, for example decided to power my Arduino from a small battery pack and my servos from another supply, perhaps a wall adaptor, I assume I would still be required to connect the grounds.
So, my question being...
Will that work?
Thanks for any advice on the matter and my apologies, if it's a ridiculous question,
Yes, I would connect the Yes, I would connect the grounds for the servo power and the Arduino power. I would connect the two grounds as close to the battery as possible.
Generally, unless there is a Generally, unless there is a very good reason not to (and the circuits are specially isolated), you always connects the grounds.
In this case, you have to connect the servo ground to the arduino ground, because that’s how the servo’s control signal is sent to the servo – between the signal cable and the ground cable.
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The grounds need connecting, in order for the signal, from the Arduino to complete a circuit, or that’s what makes sense in my mind. As there are 2 separate power sources.
However this can be done either at the battery’s negative terminals, or linking the servo’s ground to an Arduino ground.
Paul, Grounds should be connected between the servo power AND the Arduino power. Otherwise you end up with what is known in electronics circles as a “floating ground” or a “ground loop” where your circuit elements are unable to talk with each other as there is no common reference (ground) point for the elements.
The other question I see posed here is a connection between the ground and signal wires of the servo. I would not recommend this as you would be attempting to drive your servo directly to ground from your micro - a good recipe for a blown output on your micro. Often see people put resistors in series in this connection which affords a bit of protection for the micro should the servo signal wire get shorted to ground, but never connect an output pin from a micro directly to ground! A resistor from the servo pin to ground could also be useful if you have a widely different voltage levels between the servo and the micro - as long as you have one in series to the servo as well. A similar circuit is often used when you see a 5v (or higher) circuit output connected to a 3.3v micro input. Done correctly this is essentially a voltage divider circuit that translates between 5v circuit and a 3.3v circuit. Hope this helps clarify things a bit.
