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Thread: T4.1 - How to properly power and boot without USB connected?

  1. #1
    Junior Member
    Join Date
    Mar 2023
    Tampa FL USA

    T4.1 - How to properly power and boot without USB connected?

    I need to be able to power my Teensy 4.1 using Vin/GND without the USB serial and terminal connected. With Vin connected to 5v, the T4.1 powers ON, but will not boot on it's own unless I have the USB connected to my terminal application on my computer. I'm a little confused about this and would like to know the correct way to use the T4.1. Eventually, my T4.1 will reside on a PCB, in an enclosure located in a remote location with no supporting PC. Thanks for any guidance.

  2. #2
    Senior Member BriComp's Avatar
    Join Date
    Apr 2014
    Cheltenham, UK
    Do you have something like this in your setup.

    while (!Serial);

    That will wait forever if USB not attached to PC.
    You should use

    while (!Serial && (millis() < 3000));

    ...which will wait for up to 3 seconds for USB connection before giving up and running rest of program.

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