Totally separate thing now...

I think my BlueGiga dev board started malfunctioning in terms of its internal power conversions circuits yesterday.

It stopped working entirely, and I got no output from its serial ports.

Tonight I measured the voltage on several of its pins, and I did this measuring both with it hooked into my assembly and getting its voltage from there, and also when it was disconnected from my assembly and getting its voltage directly from the serial port. For places where it was supposed to be getting 3 volts, such as "VDD_IO" it was only getting 1.5 volts. And for places where it was supposed to be getting 5 volts, such as "VDD_CHG" it was only getting 4.5 volts. All other voltage test points were similarly lower than expected.

I verified that my assembly was putting out exactly the expected voltages: 4.95-5.00v on the 5v pins.

However when I connect my assembly to the BlueGiga board, the voltage on those pins drops to 4.5v.

If I take the 3v pin from the Arduino and jumper it to the 3v pin on the BlueGiga board, then suddenly it all works again. I wasn't using that pin because I had previously been using the 5v input ("VBUS") pin on the BlueGiga board. Do you think I should change that so that I use the 3V pin coming out from the Arduino exclusively instead? Or maybe both Vbus (5v) and 3v simultaneously (since Arduino outputs both)?