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I got somewhat short pulse 35ms, I written script in python using RPi.GPIO, using event and callback. Is it possible to detect so short pulses? On related question how close to 3V3 I need to get? I found

"A voltage near 3.3 V is interpreted as a logic one"

But nothing specific, I will be below 3V3 but how low can I get? 2V5 is enough? Have not run this cause still waiting on hardware that generates pulses, I just wonder if I need 555 to extend pulses. Raspberry 2 if that's important

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35ms is an eternity to a computer, although poor coding can make pulse detection unreliable.

1.3V is HIGH, although I suggest you design for 2V. See Electrical Specifications of GPIO

  • Thank you I thought so, however I am surprised with voltages. I am aiming for 2.5-3V tho with my divider so should be fine. – windman Jul 29 '18 at 20:00
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I agree with "35ms is an eternity to a computer, although poor coding can make pulse detection unreliable".

Specifically, reading a gpio value in a loop is not reliable. Configure the GPIO to generate an interrupt on leading or trailing edge and use the interrupt to process the event (or just set a flag/count that the event occurred).

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