Hi,
Is it possible to determine which power source is being used?
I'd like to be able to tell if an external power supply is being used, and am thinking about using a resistor voltage divider to bring Vin down into the 5V range so that I can send it to one of the analog inputs, does that sound reasonable?
Thanks!
Just connect the output from the Op Amp that controls the power supply switch to an input pin. I forget if LOW means Vin or USB but it will be easy to tell which is in use. The easiest place to connect is probably the Gate of the little 3-pin FET next to the voltage regulator. The gate should be the pin closest to the regulator. Follow the trace and it should go to one of the pins of the tiny 8-pin OpAmp chip.