How do I receive a TTL input signal through a GPIO? When a specific TTL signal is received in GPIO it should run some specific function.

  • You show no research = close!
    – MatsK
    Dec 6, 2022 at 18:28
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    Dec 7, 2022 at 17:48

1 Answer 1


You can use a 74HCxx gate, run it on the 3V3. TTL normally does not go to 5 volts. If yours does because of additional circuitry use a 74C14 it will do the translation for you no problem. That will do the physical translation, it is up to your software or whatever software you are running to do some specific function with the signal.

I get the impression from your comment that you want to receive some sort of serial stream, is that what 1111 or 1100 indicate. The 74C device will receive the data and simply invert it, you can inverte it again and have a copy of the original. Its goal is to to do a logic level translation which is which you initially asked about. It is up to your other logic to convert it into meaningful data. If this is correct you need to reformat your question and explain what you want to receive and its format. Since it appears serial there needs to also be a clock for synchronization.

  • Hi Thanks, How do I receive a specific TTL for example I want to do something specific when I receive 1111 other thing for 1100. How do I do that? As far as I understood from the data sheet they are gates and gives a 3.3 out. How do I receive a specific patter?
    – Paul Jose
    Dec 15, 2022 at 10:43

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