What's voltage of RPi pins 14 & 15 (RxD & TxD)?

I want to use an octocouplers, so I'm very interested in voltage parameter.


All the Pi's gpios (which include the UART RXD, TXD gpios) are 0-3.3V. A voltage outside that range will likely damage the gpio, how quickly will depend on how much current is allowed to flow.

  • Where did you see that?
    – goldilocks
    Mar 26 '15 at 14:25
  • I've connected multimeter both to the ground and tx voltage and run an output.
    – asiniy
    Mar 26 '15 at 17:41
  • 2
    @asiniy You'd be getting a PWM effect as the bits go high and low. Just check TXD and ground when idle, i.e. not transmitting data (the default idle state is high).
    – joan
    Mar 26 '15 at 17:53
  • @goldilocks ok, will try do that!
    – asiniy
    Mar 26 '15 at 22:42
  • Yep, you're right, I get 3.16V with idle txd
    – asiniy
    Mar 28 '15 at 6:59

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