I'm wanting an SDS100 for a x-country trip and I can't figure out if I can connect the GPS module and external power at the same time. There appears to be two ports - one microUSB for charging and the other for programming. If the GPS uses the programming port as the input then I suppose that the AC or DC charger can power the unit via the charger port, but if the GSP module also connects to the charger port then how can the unit be externally powered? This seems like an obvious set-up question for mobile operation.