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USB OTG on the 1st gen RPi B?

By @eisengrau2021-05-03 13:23:47.368Z

Hello,

I installed TinyPilot on my RPi B (1st generation with 256Mb RAM), I only have these devices. The video stream does work properly, however I can't get USB input to the client PC to control it, that doesn't work.

I'm using one of these USB-Y splitter cables to power the RPi from one of the regular USB-A ports, and attempted to use a normal OTG cable (microUSB -> USB-A), basically a charging cable from a Samsung mobile phone:

https://www.amazon.com/Charge-Adapter-Extension-Transfer-Charging/dp/B0711R8828/ref=sr_1_3?dchild=1&keywords=usb+a+additional+power+cable&qid=1620048002&sr=8-3

Question, for this old RPi, is it possible that its power USB port (microUSB) does not work as OTG mode, eg, provide input to the client computer?

Thank You,

  • 3 replies
  1. Michael Lynch @michael2021-05-03 21:28:46.885Z

    I'm not sure if any of the USB ports on the Pi 1 B support USB OTG. I recommend testing each port with a regular USB-A to USB-A cable before introducing anything more complicated. I recommend against using a USB-Y cable, as it introduces a risk of reverse current.

    Official support is only available for the Pi 4 B. You're welcome to seek community support for other boards, but most users are on the 4B.

    1. E@eisengrau2021-05-07 10:46:59.489Z

      Yes, unfortunately I didn't have much luck with an USB-A - USB-A cable either. Is there a config file that I can check to set which of the physical USB ports should emulate an "USB HID gadget"? Least case that I would really have to invest into a newer RPi. I do acknowledge the concerns regarding the power distribution, but right now I don't have a better choice. I'm using an original Apple charger, that seems to be quite up to spec, for now.

      1. Michael Lynch @michael2021-05-07 16:48:01.297Z

        Is there a config file that I can check to set which of the physical USB ports should emulate an "USB HID gadget"?

        No, unfortunately I don't believe there's any such setting. If none of the ports work, my guess is that the Pi 1 B doesn't support USB OTG. I know for sure that Pi 2 and 3 don't.

        I'm using an original Apple charger, that seems to be quite up to spec, for now.

        The risk exists even with power supplies that behave according to spec. The power supply is doing its job, but connecting it in a circuit with a different power supply would go against the device's intended use, so it creates a risk of reverse current.