When using a common SIM900 GSM/GPRS shield with a Uno, is it best to have a separate power supply for the GSM and Uno?
Or as I have found, when the external power supply is plugged in the Arduino only, it also seems to power the GSM shield and operate properly.
Is this an acceptable configuration with one power supply? I'm curious about the current rating of the Uno in passing power to the shield. In the mean time, I'm checking schematics for the answer.
This matters since I'd like to run this prototype on a single 7.2V NiMh battery for a few hours at a time.
I suppose I could also create a two plug splitter for the battery if necessary.