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Thread: Disable USB Port

  1. #1
    Junior Member
    Join Date
    Jan 2021
    Posts
    9

    Disable USB Port

    Hello Folks,
    for a current project I'm trying to reduce power consumption on my T3.6. The Teensy will work as a long-time sensor platform for pressure and motion (IMU) data. Therefore I've read at the low-power tips (see link) that it's desirable to turn off the USB-Port to reduce power consumption when its not used.

    https://www.pjrc.com/teensy/low_power.html

    My question now is how to do that, as I don't find any adequate information on that. Is there a specific command to disable the port and maybe even to enable it again when there is a new connection? Or do I have to reset the Teensy to enable the port again?

    To be clear, I'm not asking for external power supply issues as the Teensy will not be powered through the USB. I want to disable the whole USB Port. Does anyone know how much current this will save or is this obsolete?

    Thanks in advance
    Louis

  2. #2
    Senior Member
    Join Date
    Jul 2014
    Posts
    3,318
    I would try
    Code:
    	SIM_SCGC4 &= ~SIM_SCGC4_USBOTG;
    to switch off the USB clock
    (check usb_init() in usb_dev.c on switching on USB)

    Caveat
    I have tried it and I do not know anything about side effects.
    obvious, you cannot use usb to talk to teensy while switched off.

  3. #3
    Senior Member
    Join Date
    May 2017
    Posts
    123
    Hello,

    the link you provided was made for the AVR teensy (1.x and 2.x).
    I think you don't have to fiddle with USB for teensy 3.6, simply use snooze lib for low power.

  4. #4
    Senior Member+ MichaelMeissner's Avatar
    Join Date
    Nov 2012
    Location
    Ayer Massachussetts
    Posts
    4,090
    The datasheet for the MK66FX1M0 processor used in the Teensy 3.6 is at. There are lots of settings for USB:

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