I want to comunicate a device with the Raspberry Pi using the serial interface. I know the RPi uses 5v logic, but the issue is that my device uses 9v. I have read that the max voltage that can be supplied to the RPi to power it using the GPIO is 6v, but does this apply to the Tx and Rx lines?


  • 4
    The Pi does not use 5 Volt logic! It uses 3.3 Volt logic to communicate with a device that uses more than 3.3 volt logic you will need a level shifter or optocoupler to communicate safely. Nov 20, 2017 at 23:40
  • I think you need some extra hardware consider voltages check out this Nov 21, 2017 at 0:23
  • 2
    You CAN NOT power the Pi via the GPIO. Trying to do so will likely destroy your Pi. You can power the Pi via the 5V power rail pins on the expansion header.
    – joan
    Nov 21, 2017 at 9:01
  • @SteveRobillard Sorry, i must have seen some post with old/incorrect information. I will look for one of those devices you mentioned thanks!
    – JairoRB8
    Nov 21, 2017 at 18:26

1 Answer 1


The Pi uses 3.3V logic! Even at 5 V you will probably destroy your device, never mind 6 or 9V. All of the GPIO pins are 3.3 V logic, including Tx and Rx.

  • Oh okay, thanks! Will look for an adapter cable or some level shifter.
    – JairoRB8
    Nov 21, 2017 at 18:23

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