How can I be sure if the OTP hasn't been fused before? (STM32MP153)

[DLiu.4]

I am getting "Error: can't fuse again in the OTP" when I tried registering a key on boards that shouldn't have been fused before. Is there a way to confirm if they are fused?

Heres a picture of the output:

 

Am I missing a step? I've been following "STM32 MPU ROM code secure boot" and "How to use U-Boot stm32key command" articles on how to enable secure boot.

[PatrickF · Accepted solution]

Hi @DLiu.4​ 

You should know an OTP has been fused by reading its value, if it is different from 0 it has been fused.

You should also read the lock as it could be 0 but locked.

If needed, lower range OTP (0 to 31) could be fused bit by bit whereas upper range OTPs (32 to 95) must be fused only one time with 32-bit value

Here you see Public Key Hash values at 0xFFFFFFFF and locked. This mean you are using a device without secure boot option (STM32MP153A or STM32MP153D).

To use secure boot, you must use an STM32MP15xC or STM32MP15xF.

Regards.

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