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JOLSO.11
Visitor II
July 6, 2024
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32F413 Port Pin States During Deep Sleep?

  • July 6, 2024
  • 1 reply
  • 941 views

I'm the hardware guy on a 32F413 project where we have a lot of impulse noise nearby on the PCB.  Because of this I've been on a campaign to make certain that all microcontroller I/O pins are equipped with pull-up or pull-down resistors.

The project has reached the stage where our quality assurance folks get cranky whenever I try to add a resistor to this PCB.  So when I find a 32F port pin that is missing a pull up/pull down resistor (as I did this week) it becomes a crisis of meetings and memos.

Remind me to never work again in a medical equipment company.

So I approached our firmware guy and asked him to alter his code to make certain the offending port pin is equipped with either an internal pull-up or a pull-down during his sleep mode,

Firmware guy replies:  "No can do, hardware guy.  The micro is in its deepest sleep state and the port pins flap in the breeze during deep sleep.  You must fix that undefined I/O state with an external resistor. Luv ya, big guy..."

Is this true?  Do all port pins go to tri-state mode during deep sleep?

    This topic has been closed for replies.
    Best answer by AScha.3

    >The micro is in its deepest sleep state and the port pins flap

    Depends on the sleep mode , if its Standby ...then, from ds:

    AScha3_0-1720284684601.png

    and from rm:

    AScha3_1-1720284716481.png

    So some pins still working (to wake up cpu) , but all other ... hi Z , off.

    So better put a pulldown/-up on every output pin, that would float otherwise.

    I do this always on "important" output signals, just because on every start/powerup the cpu is in reset and all (almost all) pins floating anyway. 

    (Input pins should anyway have some fixed state, from the circuit the signal is coming from.)

    1 reply

    A
    AScha.3Answer
    Super User
    July 6, 2024

    >The micro is in its deepest sleep state and the port pins flap

    Depends on the sleep mode , if its Standby ...then, from ds:

    AScha3_0-1720284684601.png

    and from rm:

    AScha3_1-1720284716481.png

    So some pins still working (to wake up cpu) , but all other ... hi Z , off.

    So better put a pulldown/-up on every output pin, that would float otherwise.

    I do this always on "important" output signals, just because on every start/powerup the cpu is in reset and all (almost all) pins floating anyway. 

    (Input pins should anyway have some fixed state, from the circuit the signal is coming from.)

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