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Thread: Teensy 4.0 power button

  1. #1
    Junior Member
    Join Date
    Sep 2019

    Teensy 4.0 power button

    Can someone tell me what the proper connection is for the power pushbutton on the 4.0? I assume it is a normally open with a connect to ground when closed, but I can't actually find anywhere this is documented, and I hate assuming....

  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    There are notes around … I know I typed most of this recently ...

    > left open the Power pin is held 3V+.

    > when T4 running 'ON' : and Power pin is grounded for about 5 seconds the T4 goes OFF and the 3.3V regulator is turned off

    > when T4 'OFF' but given VIN: and Power pin is grounded for about 0.5 second the T4 goes ON and Teensy 4 turns ON and begins fresh through setup()

    > If the RTC** battery is connected the On/Off state can be changed as above even when not VIN powered

    > If the RTC** battery is connected the On/Off state persists across removing VIN power

    > With NO RTC battery connected and no VIN, the On/Off state reverts to ON given VIN power

    > ** when 'some' amount of external power is presented to the T4 GPIO when OFF - like UARTS at 3+V on multiple I/O pins - it feeds power to the RTC system as if a battery were connected

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