I have an Arduino Uno and a Raspberry Pi that I'm using to control some LEDs in a computer case. Power is coming from a Molex connector from the computer's PSU. I want to place the Arduino and the Pi at the top of the case, but the power supply is at the bottom. In order to try and reduce the length of wire runs, I'd like to power one of the devices from the other.
When I supplied 12V to the Arduino through the Vin pin and tried to supply 5V to the Raspberry Pi via the 5V pin, I ended up frying the Arduino (too many amps?). I was wondering if I could do the inverse: supply 5V to the Arduino through the GPIO 5V pin, then provide 5V to the Arduino through the other GPIO 5V pin. According to the diagram here:
there are two 5V pins and five ground pins that I can use. I'd like to prevent against frying something else though. Will my idea work, or is this a foolhardy idea?