Does anyone know will the Raspberry Pi 2 GPIO pins count a 1.8V input as logic one or logic zero?

  • This question has been prematurely (and inaccurately) marked as a duplicate (as many questions seem to be before the users get a chance to comment) (the supposed duplicate mainly addresses current and does NOT answer the logic level question). See raspberrypi.stackexchange.com/a/60219/8697 There is no definitive answer. 1.8V would almost certainly be HIGH.
    – Milliways
    Feb 16, 2017 at 10:37
  • @Milliways The linked duplicate refers to input voltage levels using the same link to the same mosaic-industries.com paper that's been referenced by your suggested answer. I can't find any definitive numbers for input voltage thresholds specified in this question, your question, Ghanima's suggested duplicate, or the mosaic paper. As long as we're all guessing, and basing the guesses on the same source, I'm not sure there's much to be had from quibbling over whose stab in the dark is the best one.
    – goobering
    Feb 16, 2017 at 11:48
  • @Milliways, joans answer at the linked "duplicate" addresses the voltage level same as in their answer here (that is by definition what makes questions duplicates to each other - it has the same answer). Technically your other Q could also be considered a duplicate and your elaborate answer could be an answer to the one linked here in the first place. I will not argue which spec (those in your answer or those linked by joan) unless we get numbers straight from the horse's mouth. (Obviously I will leave the re-open vote to community.)
    – Ghanima
    Feb 16, 2017 at 12:04

1 Answer 1


Probably neither. 1.8V is probably in the hysteresis region and could be seen as arbitrarily low (0) or high (1).

See http://www.mosaic-industries.com/embedded-systems/microcontroller-projects/raspberry-pi/gpio-pin-electrical-specifications

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