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Thread: Teensy 4.1 USB Host port with no 5V on VIN?

  1. #1
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    Teensy 4.1 USB Host port with no 5V on VIN?

    I would like to use the USB Host port on a Teensy 4.1 to communicate with a CDC USB Device.
    I understand the USBHost_t36 library exists to enable this.

    Since I'm running the Teensy 4.1 from the 3.3V rail on my PCA, the USB Power trace is cut and there
    is no 5V supplied to VIN. What would be the best way to power USB2? (assuming there is a best way)
    The Teensy's onboard 3.3V regulator won't run the rest of my PCA, so I can't just reconnect the link between
    VIN and VUSB and power it that way. Have I painted myself into a corner?

    Thanks!

  2. #2
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    I actually have the same question. Did you solve your problem? Could anybody help here?

    What I don't understand is how I could provide enough power (more than the 250mA provided by the onboard regulator) on the 3.3V rail with an external regulator, but still use 5V with another regulator on VIN to power the USB host device. Is that even possible?

  3. #3
    Senior Member+ Frank B's Avatar
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    Just power the Teensy with 5V (cut the pads) and don't connect the new 3.3V rail to the Teensy. Note, don't forget to connect GND.

  4. #4
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    I think the question is about a Teensy that is not powered from USB and thus has no source of +5V for the Host USB connector. You will need to provide external +5V for that. What is driving the 3.3V regulator on your base board?

    If it is about an existing setup, you may need to cut and bodge to get host power.

    If this is a design question, add a 5V regulator. You may also want to add a USB power manager to prevent shorts or other problems with the USB device from killing your power supply.

  5. #5
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    It was a design question (still on breadboards), so I will follow Franks path of having devices on a separate 3.3V rail and providing 5V to teensy, thus having all the protection and convenience.
    Thanks anyway!

  6. #6
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    Quote Originally Posted by Tom Kuhn View Post
    It was a design question (still on breadboards), so I will follow Franks path of having devices on a separate 3.3V rail and providing 5V to teensy, thus having all the protection and convenience.
    Thanks anyway!
    Which is what I should have done.
    I have the rail on the PCA, but didn't think about it until after-the-fact.

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