Some of the microcontroller options bytes were changing by itself.

[Mkuma.7]

The option bytes WRP1A_STRT =  0xFF, WRP1A_END =  0xFF, WRP1B_STRT = 0xFF and WRP1B_END = 0xFF
were programmed initially, then it got changed to WRP1A_STRT =  0xFF, WRP1A_END = 0xFF, WRP1B_STRT = 0xFF and WRP1B_END = 0xFF. I don't know when and why it got changed.

Do you guys know what's the root cause behind this?

[Sarra.S]

Hello @Mkuma.7, 

I am not sure I can see any changes :thinking_face:

[Mkuma.7]

Sry @Sarra.S 
--> The option bytes WRP1A_STRT =  0xFF, WRP1A_END =  0xFF, WRP1B_STRT = 0xFF and WRP1B_END = 0xFF were programmed initially using CLI. It was successfully programmed.
-->  But in 2 of the cases these fuses were overwritten as shown  WRP1A_STRT =  0x0, WRP1A_END = 0x1, WRP1B_STRT = 0xFF and WRP1B_END = 0xFF. I don't know when and why it got changed. But we are using the same programming procedure (using CLI)

So How are these 2 FUSES WRP1A_STRT ,WRP1A_END got overwritten even when I am giving default values as 0xFF and 0xFF respectively.

[Issamos]

Hello @Mkuma.7 

I suggest you to take a look to the part 2.2.4 of the ES0500.

II

[Mkuma.7]

@Issamos 
The errata that you pointed out is for the STM32WL series, but we are using the STM32WB series.

Will this errata holds good for WB series?

[Issamos]

Sorry @Mkuma.7 

For the STM32WB, I suggest you to use cube programmer to change the option bytes values.

Best regards.

II

[Mkuma.7]

@Issamos 
We are eliminating the use of Cube Programmer and programming the controller via USB using STM32_Programmer_CLI.

[Mkuma.7]

This became a big issue for us!!

Can you guys give a proper solution for that?

[Tesla DeLorean]

Any particular circumstances where you observe this occuring?

If the values are critical to your application it should check and report them at each startup, and then reestablish the correct values you want if they are not currently correct.