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TAcha.1
Associate
Mar 5, 2021 11:38 PM UTC
Solved

Where can I find documentation on the I/Os that are not floating during and after reset?

I am using STM32H745ZI for a personal project. Page 60 of the attached datasheet from ST says there are I/Os that are floating unless otherwise specified. I want to use an I/O that I can guarantee will be in either low or high state on a reset or if the processor stops working.

My goal is to find an I/O that I can be certain will be in a particular state (high or low) at reset or if the processor is not working but has power.

Any help is appreciated.

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Tesla DeLorean
Tesla DeLoreanBest answer
Guru
Mar 5, 2021 11:41 PM UTC

The Reference Manual would show the initial state of the GPIO registers.

NRST has a pull-up, clamped to zero if POR for VDDA below threshold

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3 replies

Tesla DeLorean
Tesla DeLoreanBest answer
Guru
Mar 5, 2021 11:41 PM UTC

The Reference Manual would show the initial state of the GPIO registers.

NRST has a pull-up, clamped to zero if POR for VDDA below threshold

Tips, Buy me a coffee, or three.. PayPal Venmo (See Profile) Up vote any posts that you find helpful, it shows what's working..
TAcha.1
TAcha.1Author
Associate
Mar 8, 2021 3:24 PM UTC

Thanks for replying Tesla.

I have perused through the reference Manual but the notes section has no information on the initial state of the GPIO's that are non floating.

Amel NASRI
ST Technical Moderator
Mar 10, 2021 1:38 PM UTC

Hi @TAcha.1​ ,

Look to the reset values of GPIO registers in the reference manual (RM0399) to get the exact answer. Here an example:0693W000008wWopQAE.png 

Pins used for debug purpose are the ones where there is an exception:

0693W000008wWnDQAU.png-Amel

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