How can I safely power the Arduino through the 5V pin and utilize the USB connection?
I've searched but haven't found a totally clear answer on this.
I have a project using a bunch of Sharp IR distance sensors and some ultrasonic range finders with a Mega 2560. Everything worked well initially but once I added all the sensors, I think we were overloading the USB port as the 5V rail was only giving around 4.25-4.5V. I used a benchtop 5V supply to power the sensors (grounds tied of course) and left the Arduino on USB. The IR sensors worked fine, but I found the ultrasonic sensors act up when powered by a separate power supply, returning bogus numbers (im using SRF01's). Disconnecting the USB and powering the Arduino through the 5V pin with the bench supply so everything was being fed by the same power supply, everything worked fine.
Problem is- I need the USB connection for debugging. So my question is again: How to safely power through the 5V pin AND use the USB connection, or is it even possible? - Can I just cut the 5V line on the USB cable? Will the USB converter power off the 5V pin from the board or is the 5V USB connection its only power source? - I have a FTDI breakout cable. I assume I could also just use that and not connect the power pin to the board. If I did that, what pins need to go where from the cable to the board?