I think I remember reading something about people frying their uno r3 serial chips by using a separate power supply while having it plugged into USB.
I'm working on a project that requires the arduino uno r3 to be powered by a separate power supply AND have the usb cable connected to a PC for serial communication. When using a separate power supply, the board will reset sporadically and serial communication will fail after a few minutes. To isolate any cause I have disconnected all wiring from the arduino pins, and am just running a bare board. It still resets randomly and has serial communication failure when using the separate power supply. Any ideas where I can start troubleshooting this? The tx/rx lights still activate when it has failed, but my terminal receives nothing. Thought it might be a grounding issue but I measure 0V from USB ground to the barrel -.My search terms for this problem brought up nothing, but I think I remember reading something about people frying their uno r3 serial chips by using a separate power supply while having it plugged into USB.EDIT: Power supply is 12V 1.5A regulated. Reads 12.3V on a dmm. under arduino load, 12.27v. I will attempt using a different supply but suspect the problem will remain.