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STM32F407 Option Byte 0xFF, bricked chip

Ratschaka
Visitor

‎2025-12-11 1:15 AM

Hi fellows,

I have a custom board with STM32F407VGT6. The board was able to be programmed via the JTAG (4 wire JTAG interface; Boot pin is pulled low to ground and reset is connected to the JTAG interface (Nrset pin)) with a segger programmer - multiple times at that and can run for hours, however sometimes it code wipes.

 

The board works fine for some time, but only upon boot-up (at random, happened twice thus far) we have seemingly a code-wipe as well as a bricked chip with the RDP set to 0xFF and unable to do anything with the chip. This does not happen during continuous running of the chip.

 

We have this across 2 differently designed boards, which are designed according to the reference manual for power supply and for the tests were supplied with external linear regulator with low noise.  

 

I have seen some posts here but not conclusive solutions or cause for this issue, is it possible to trigger this externally via hardware faults ?

The chip reports back correctly via the STM32Cube Programmer (V2.18) but unable to download or erase flash as option bytes can't be read and report as 0xFF.

 

Does anyone have ideas or explanations for this behaviour ?

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mƎALLEm
ST Employee

‎2025-12-11 1:27 AM

Hello @Ratschaka and welcome to the ST community,

Such kind of issues needs from you more details: the schematics + the code you are using to reproduce the issue.

Please read How to write your question to maximize your chances to find a solution

 

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.
Ratschaka
Visitor

‎2025-12-11 1:38 AM

Hi thanks for the reply,

I can not post the full schematic as it is propriety, however the power supply setup is as follows:

Ratschaka_0-1765445626541.png

Regarding the code, we are not deliberately setting the option bytes at all and checked this - hence the question if this is even possible to be set "accidently" or through corrupted code (during loading of the program from the flash).

I do not see how externally we could trigger a code wipe + setting the option bytes, as it happens at random during boot-up.

Is there any specific code segment that might help diagnose this issue, so I can check if it is possible to share this snippet.

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