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guansonghuang
Associate III
July 17, 2024
Solved

stm32mp135f otp can't fuse again

Hi st frends:

  Yestarday I fuse the OTP PKHTH as follow

guansonghuang_1-1721187899535.png

But today I found  the key I fuse is not the correct one. So I want to re-fuse the OTP ，it seems that can't no fuse again.  is there any way to fuse the OTP this situation?

guansonghuang_0-1721187724783.png

 

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PatrickF
PatrickFBest answer
ST Employee
July 17, 2024

HI @guansonghuang 

unfortunately, this is not possible.

on upper OTPs (31 to 95), trying to program a different value will likely make the platform bricked as embedded ECC protection cannot be correct as well (as fused bits cannot be cleared).

On lower OTPs (0 to 31), you could only sets new bits to '1', but once set, a bit cannot be cleared (this is intrinsic to the fuses).

Refer to reference manual

PatrickF_0-1721197461439.png

Regards.

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3 replies

PatrickF
PatrickFBest answer
ST Employee
July 17, 2024

HI @guansonghuang 

unfortunately, this is not possible.

on upper OTPs (31 to 95), trying to program a different value will likely make the platform bricked as embedded ECC protection cannot be correct as well (as fused bits cannot be cleared).

On lower OTPs (0 to 31), you could only sets new bits to '1', but once set, a bit cannot be cleared (this is intrinsic to the fuses).

Refer to reference manual

PatrickF_0-1721197461439.png

Regards.

In order to give better visibility on the answered topics, please click on 'Best Answer' on the reply which solved your issue or answered your question.Tip of the day: Try Sidekick STM32 AI agent
guansonghuangAuthor
Associate III
July 17, 2024

hi @PatrickF   by the way, what is the meaning of lock as follow

lock: 1000000

and 

lock: 5000000

 

PatrickF
PatrickF
ST Employee
July 17, 2024

From that page, you could see

PatrickF_0-1721209587775.png

 

0x10000000 is "Shadow write sticky lock"

0x50000000 is "Shadow write sticky lock" + "Permanent write lock"

 

Regards.

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