I would like to connect 3 USB keys on an arduino.

I just want to detect the presence of the 3 USB Key. I do not want to read or write on the keys.

Is there a basic way to do that ?


  • Do you need to know that they are USB keys, or will just the presence of any three devices being connected suffice?
    – Majenko
    Oct 1 '20 at 10:37
  • Some, but not all, USB devices have the outside/shield of the USB A plug connected to to the GND pin. If so you could connect the ground pin of you female USB A socket connected to GND of the Arduino, and the shield connected to one of the pins of the Arduino (with a (internal) pull-up resistor).
    – Gerben
    Oct 1 '20 at 14:39

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