The BrainStem GP 2.0 and CMUCam2+ share a common approach to allowing both shared power for servos as well as auxiliary power for the servos.  Since servos can create high transient spikes that can wreak havoc on logic circuits, we provide this shared concept to allow you to isolate the power if needed or desired. 

While this is very simple, people routinely stumble on the details so a diagram is probably the best way to describe this:

As you can see, there are two choices.  The jumper approach (shared power) feeds the UNREGULATED logic supply power to the servos.  This works great if your logic supply voltage is within the specs of the servos being used and there are no noise issues being created by your servos with the logic side. 

The auxiliary power approach requires a separate power supply that is within the specs of the servos to provide power to just the servos.  Notice that this approach ties the grounds of the two supplies (logic and aux servo) together which is required....  but also should be understood. 

Hopefully this clears up the confusion with the alternatives for servo power on the GP 2.0 and CMUCam2+. 

Revision History:

• 2008-04-10: How To: connecting servo power to the CMUCam2+ or GP 2.0

Related Links:

Comparing and Explaining the Acroname Servos

Related Examples:

Example BrainStem code for scanning with an Eltec 442-3 Pyroelectric sensor