I'm about to build myself a new BrewPi and I have some Arduino power/USB questions.
Something smiliar to a combination of these projects:
The device will have a Raspberry Pi Zero W, an Arduino UNO (clone?), a LCD screen with backlight, and some relays and probes. The Pi must be connected to the Arduino via USB. The Arduino will drive the screen and some relays/probes. For simplicity's sake, I would like to power everything from the same regulated 5V power supply, and for ease of wiring I would prefer to power the Pi only and have it power the Arduino via USB, with the Arduino then supplying power to the rest.
My preference: 5V ----> Pi Zero --(USB)--> Arduino --(5V)--> Screen/etc.
However, according to this datasheet the max draw of the screen might exceed 1000mA: https://www.vishay.com/docs/37314/lcd020n004l.pdf
This obviously exceeds the 500mA limit from the Arduino's 5V pin while being powered via USB. However, a Pi Zero has few safety features and does not limit outgoing current from it's USB port: https://www.reddit.com/r/raspberry_pi/comments/3zyhuq/pi_zero_usb_power_outputmilliamps/
Given this, is it feasible to short/bypass the Arduino's polyfuse and then draw more than 500ma from the 5V pin of the Arduino without too many problems?
If not, can I 'add' the power supply's 5V to the Arduino's 5V (either from the Pi's 5V pin, or direct from the power supply) at the same time as maintaining the USB connection (which uses the same 5V source)? I'm stretching the limit of my circuit understanding here. If not how should I power the other components?
Would it instead be better to have a 12V supply and power the Arduino directly, then attempt to power everything else from its 5V pin (remembering that there is still a USB connection from the Pi back to the Arduino). What I'd really like to avoid in this situation is having to provide a second 12V->5V conversion.
Any help or advice would be greatly appreciated.