I was wondering if anyone has used a raspberry pi with more than one RPi hat module. I was hoping I could use a relay board with the POE heads at the same time. I would attempt this right now but I do not want to risk frying my RPi and since I can't find another other answers online I felt the need to ask instead of search. Please let me know if any of you know or have done something similar. Thank you for your time.

Edit: Hey, sorry for being a little vague. The RPi hats I would like to use are these: https://www.amazon.com/Raspberry-PoE-HAT-Profile-Heatsink/dp/B09FYQ8GCT




I am looking to use these in several configurations such as Relay board and POE hat, Relay board and the terminal block, or terminal board and POE hat. Any and all information is appreciated. Thank you very much again.

  • 1
    What do you mean by "head"? Do you mean "hat"?
    – tlfong01
    Sep 26, 2022 at 6:15
  • 1
    Your question will benefit from you being more exact. Which exactly hats you want to combine? Add links to datasheets in your question.
    – Vadim
    Sep 26, 2022 at 9:11
  • Are you talking about car GPS/radio stuff? Perhaps you can give us a link to your head unit.
    – tlfong01
    Sep 26, 2022 at 9:45
  • Like these? Raspberry Pi Head Unit (1) youtube.com/watch?v=ko-udLtaPk8, (2) youtube.com/watch?v=IpvGRm4q_Lc, (3) youtube.com/watch?v=odn8OfE5FdI.
    – tlfong01
    Sep 27, 2022 at 9:03
  • I realize "heads" was perhaps a pun about hats, but it also has a potential real meaning here which has nothing to do with what you are talking about and hence may confuse the issue (= title changed).
    – goldilocks
    Oct 29, 2022 at 13:24

1 Answer 1


Before answering the questions about compatibility of the hat combinations you may want to have a look at the issues of POE+ HAT. Depending on what you are up to, it may or may not affect your project.

  1. With regards to combination of the Relay board and POE hat:
    • The hat seem to provide 5V, 4A power on the 5V pins. As long as I can see (you may need to double check it), it doesn't use any other pins.
    • According to the schematics, the relay board needs 5V power (the output of POE+ hat should be good enough) and IOs 20, 21, 26.
    • Assuming the above is true, the boards should be compatible. I would not risk to use both USB-C power and POE+ at the same time (see also 1st link), but you may want to investigate on it yourself.
  2. With regards to combination of terminal board and POE+ hat:
    • Assuming above statements about POE+ hat are valid
    • The terminal hat provides negligible additional functionality to Pi GPIOs. Essentially it only adds LED indicators. Meaning all GPIOs that are not used by the other hats should be available to you.
    • With the considerations mentioned above, the two hats should be compatible. Pay attention to the power you need when connecting peripherals to GPIO and power lines and keep in mind issues with POE+ hat mentioned above.
  3. Relay board and the terminal board:
    • Assuming you will use USB-C to power your Pi and peripherals and you are aware that Pi ain't a power supply
    • Assuming you want to control relays with your Pi GPIOs, not from terminal board
    • You should let IOs 20, 21, 26 free in the terminal board to have the hats compatible. As mentioned above, consider power requirements of whatever is connected to the terminal board.
  • Thank you very much. Your answer really helped me out. Oct 1, 2022 at 2:53
  • My pleasure! If it answers your question, please put a tick and consider closing the question
    – Vadim
    Oct 1, 2022 at 11:33

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