I’m working on a project that will combine a RPi and Arduino Mega together. The two are connected via USB cable primarily for the purpose of data exchange. My question is should I provide the Arduino with its own power supply or use the USB connection from the RPi, letting the RPi provide the power? Please note that the Arduino has no significant load other than itself.
My project will include its own PSU for the RPi (and Arduino if necessary), and I can make sure it has as much power as needed.
If the answer is give the Arduino its own power supply, then is it possible to connect that to the USB or use the 7+V power input? Would clipping out the Vcc wire from the USB cable solve anything or create new problems?
The Mega should only draw about 20 mA and the Raspberry Pi should be able to supply 500 mA if it's source power supply (and associated cabling) is up to the task. In particular it is important to use a good quality and reasonably short USB cable between the USB power source and the Pi. If you have a monitor on the Pi, it will give an indication if it detects a "brown out" condition indicative of inadequate power.
Quite a few people, myself included, have run the Arduino development system on Raspberry Pi with one or more Arduino boards attached routinely.
The Mega should only draw about 20 mA
A Mega draws AFAIK almost 70mA.
But it makes no difference to the answer.
No, but it should be corrected.
It might be repeated in another thread.