Hello, can I power the raspberry PI from the automation hat? i.e. if I connect 5V to the automation hat do I also need to power the raspberry pi via the micro usb port?
It depends where you put the 5V and how stable a supply it is. I’d always use a separate 5V 2.5A mains adaptor for the Pi just for sanity’s sake, but your mileage may vary depending on your use case (no mains if you’re using batteries for example)
Bear in mind the common connections for the relays are isolated from the Pi, so 5v there would do nothing, but connecting 5V/GND to the labelled pins on the Automation HAT should backpower the Pi albeit it would lack the protection diode detailed here unless you added it yourself: https://github.com/raspberrypi/hats/blob/master/backpowering-diagram.png
(Note: this diode is to prevent bad things happening if you connect a power supply to the HAT and the Pi)
So, TLDR: Yes. But it wasn’t designed with this in mind.
OK - sounds like intended use is other way around. i.e. raspberry pi powers the HAT internal circuitry. Is that right?
- Use a stable dual output power supply (12V, 5V)
- Connect +5v from power supply to PI via micro USB
- Connect common from Power supply to ‘GND’ on hat
- Do not connect anything to ‘5V’ on hat so bad things don’t happen
- +12V from power supply wires to my sensor device (+10V output) then to buffered input #1,2,3
- Use relays as dry contact outputs
Is that right?