there. I am trying to use rpi 4 to access my own device through UART. However, the number of UART port isn't enough for me since I'm trying to access more device in same time. Thus, I want to know if it is possible to access UART data from USB port. Further more, if it's possible to access from USB hub to connect with more devices. If it's possible, how to achieve my goal?

Thank you.

  • Well, for Rpi4B on board Tx/Tx serial port, you can have 5. For UART serial ports, you can has as many as you want: Multiple Rpi Serial Ports Problem raspberrypi.stackexchange.com/questions/98393/…. Cheers.
    – tlfong01
    Jun 17 '20 at 3:29
  • This lab log shows how to do Rpi4B 5 onboard serial ports: penzu.com/p/f2cb232e. Cheers.
    – tlfong01
    Jun 17 '20 at 3:33
  • 1
    Note that the Pi4s internal UARTs run at 3.3V, and many devices require at least 5V. You'll also brick the pi if the other device uses a 5V (or even 15V) level. Use a level shifter or an inverter IC.
    – PMF
    Jun 17 '20 at 9:55
  • @PMF, Yes, it is a good idea to learn how to convert Rpi 3V3 signals to 5V. My answer to the following question has an example of using TSX0108E to do such an conversion: raspberrypi.stackexchange.com/questions/96184/…. Cheers.
    – tlfong01
    Jun 17 '20 at 13:28

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