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HRadt.1
HRadt.1
Associate III
Sep 29, 2020 10:36 AM UTC
Solved

Refreshing IWDG without initializing it causes FLASH->SR->CFGBSY to be set

When trying to refresh IWDG when it has not been initialized, causes the FLASH->SR->CFGBSY bit to get stuck on SET. It will not return to zero ever.

Also mentioned in this post: https://community.st.com/s/question/0D50X0000Bh5LOVSQ2/trouble-programming-flash-with-halflashprogram by JHuan.1

I couldn't find anything in the reference manual, nor in the errata sheet of the STM32WB55 cpu. Is there a link between IWDG and FLASH that I'm not aware of? Or how could IWDG have any effect on FLASH?

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HRadt.1
HRadt.1Best answer
Associate III
Sep 29, 2020 8:31 PM UTC

Okay, this one is clearly my fault, but in case someone stumbles on the same symptoms:

Not calling MX_IWDG_Init() leaves the hiwdg handle uninitialized. Invoking the refresh through the HAL then effectively causes a flash write to address 0, which is an alias for FLASH_BASE (0x08000000). Just writing that address then causes the CFGBSY bit to get stuck.

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HRadt.1
HRadt.1AuthorBest answer
Associate III
Sep 29, 2020 8:31 PM UTC

Okay, this one is clearly my fault, but in case someone stumbles on the same symptoms:

Not calling MX_IWDG_Init() leaves the hiwdg handle uninitialized. Invoking the refresh through the HAL then effectively causes a flash write to address 0, which is an alias for FLASH_BASE (0x08000000). Just writing that address then causes the CFGBSY bit to get stuck.

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