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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.

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  • 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 '20 at 7:20
  • logic level voltage would be 3v3. I will edit – SwampyX Jan 5 '20 at 12:49
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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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  • ok. Thank you! I wasn't sure whether the gpio pins would go into some sort of "null" state which could damage the pi. I will also add a protection circuit just in case. – SwampyX Jan 5 '20 at 12:49

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