I have this adapter (https://global.rakuten.com/en/store/denshi/item/55154/) powering a set of RGB screens that I picked up from adafruit. Essentially I completed their pi/rgb matrix project and want to enclose it into a frame (with easy access of course) but I was wondering if I can power both the pi and the screens with this adapter. I don’t really want to have 2 plugs going to the frame. If I could use just 1, that would be ideal.
The Adafruit RGB Matrix + Real Time Clock HAT includes a 5V power output via the solder pads circled in the attached image.
According to the Adafruit RGB Matrix + Real Time Clock HAT documentation, the HAT has onboard power protection circuitry:
Power protection circuitry - you can plug a 5V 4A wall adapter into the HAT and it will automatically protect against negative, over or under-voltages! Yay for no accidental destruction of your setup.
According to the Adafruit PCB layout and schematic, the 5V output pads are downstream of the protection circuit.
This means that it would technically be safe to wire this into the GPIO (MAKE SURE IT'S THE 5V PIN!!!) of your Raspberry Pi, but note as per Bob Brown's comment above you must be aware that you are bypassing the Raspberry Pi's protection circuitry and "trusting" the HAT's protection.
Another solution is to modify a micro USB cable by cutting off the end and wiring the 5V and GND wires from the miro usb cable to the HAT's power output and plug that into the Pi's micro USB port (Making absolutely sure you have the USB cable pinout correct).
Both of these solutions would allow you to power everything off the one power adapter and give a reasonably tidy end product.