BulletMagnet83:
Given their low cost I'd really REALLY consider using an LDO regulator when running from batteries. I wouldn't feel comfortable feeding any microcontroller-based project from an unregulated supply, even from batteries. It doesn't really add much complexity to the circuit
One of the aspects of the way we're workshopping with the ATMEGA chips is to try and maintain continuity as much as possible from one stage to the next. Ideally the exact same solderless breadboard circuit powered off the CP2102 attached to a laptop is transferred to stripboard wholesale, without having to rethink or rewire it. One way to go is to include the LDO regulator in the circuit even when it's not strictly needed (e.g. when attached to the regulated USB supply). That way we can switch seamlessly from the USB-connected lab-prototyping mode into a battery-operated in-the-field mode without any sleight of hand.
Do you think this would work? I gather there's a loss of voltage when going through a regulator, but given the spec of the component you described this may not be significant.