I have a Raspberry Pi 2 Model B, and I plan on using the GPIO pins to detect whether a voltage is present or not. However, the circuit that controls the voltage levels runs independently from the pi, and I just wanted to know if a 3v3 at the pins could harm the pi if the GPIO pins aren't specifically in use, or the pi is turned off/loses power.

  • Please define "logic level voltage". Anything over 3.3V will kill your RPi. Information on the circuit/device that controls the voltage might get you a more detailed answer. There are numerous methods for limiting the device output to a safe level, but the right one "depends": voltage dividers, zener diodes, opto-isolators...
    – Seamus
    Jan 5, 2020 at 7:20
  • logic level voltage would be 3v3. I will edit
    – SwampyX
    Jan 5, 2020 at 12:49

1 Answer 1


If unconfigured GPIO pins are Inputs, so safe for a logic input 0 - 3.3V

If Output and opposite voltage is applied they can be damaged - which is why you should use a series resistor to limit current to a safe level.


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