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MFolk.1
Senior
April 21, 2022
Solved

Do GPO pull-ups/pull-downs hold their hardware configured state through power cycle?

  • April 21, 2022
  • 1 reply
  • 743 views

I am using STM32L4S9AII6 MCU.

I am exploring options to ensure that certain outputs are forced to a known safe state during power up. I want to be able to take advantage of the MCU's built in GPO pull-up and pull-down configuration features, but I am worried about the interval of time between when the MCU receives supply power at startup to when the MCU gets to initializing the GPO pins as pull-ups or pull-downs at the beginning of the program.

If I configure a GPO pin as a pull-up or a pull-down, does that hardware configuration remain physically in place through the power cycle process?

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Best answer by Tesla DeLorean

>>If I configure a GPO pin as a pull-up or a pull-down, does that hardware configuration remain physically in place through the power cycle process?

NO

Assume anything you want in specific states at power-up, through initialization is done externally.

The initial register states should be in the RM, with most going into floating input states.

Watch also what the ROM Boot Loader might have expectations on for specific pin usages, in AN2606

1 reply

Tesla DeLorean
Tesla DeLoreanBest answer
Guru
April 21, 2022

>>If I configure a GPO pin as a pull-up or a pull-down, does that hardware configuration remain physically in place through the power cycle process?

NO

Assume anything you want in specific states at power-up, through initialization is done externally.

The initial register states should be in the RM, with most going into floating input states.

Watch also what the ROM Boot Loader might have expectations on for specific pin usages, in AN2606

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