New batch STM32F051 LSE don't start

[passafabio2]

A new batch of electronic board mount an STM32F05R8T6

AA170 9U

TWN AA 131 marked.

All of this devices don't start up LSE clock.

The code is the same for about five years and makes the LSE clock start up till this days correctly. The initialization was made using example code bundled with discovery stm32F051.

I create with CubeIDE Version: 1.9.0 a minimal setup (CubeMX) for initializa internal RC but the code hangs on

while(__HAL_RCC_GET_FLAG(RCC_FLAG_LSERDY) == RESET)
   {
    if((HAL_GetTick() - tickstart ) > RCC_LSE_TIMEOUT_VALUE)
    {
     return HAL_TIMEOUT;
    }
   }

The quartz is the same sice five years and i try to modify the capacitor from 15nF to 6,8nF with no success.

Same board with STM32F05R8T6

GQ272 9U

CHN GQ 944 marked

run perfectly.

Any ideas?

Thanks 

Fabio

[waclawek.jan]

Have you tried any of what I wrote above, e.g. playing with LSEDRV?

JW

[passafabio2]

Yes changing LSEDRV nothing happen.

And untill this batch of micro we made about one thousand of board with LSE Ok...

[TDK]

Try replacing the STM32 chip on a new board with one from an old board.

[passafabio2]

Yes nothing change...

Thing change using older batch STM32F051...

[waclawek.jan]

At this point you may want to contact ST directly, through FAE or the web contact form.

JW

[Amel NASRI]

Hi @passafabio2​ ,

As suggested by @Community member​ , I'm checking internally if there is any noted change regarding LSE as I'm not aware of any update.

In such case, a failure analysis request (FAR) will be required and needs to be initiated by your FAE.

-Amel

[passafabio2]

Yes nothing change.

[Tesla DeLorean]

Hi @Amel NASRI​ 

I'd assume there's a new RM0091 somewhere covering the new ICs, the one publicly available is over 5 years old, and clearly not up to date.

Even if it is a new/duplicate mask-set for a new fab.

"9U" is the TSMC USA Fab 11

"98" is the TSMC Taiwan Fab 8

And in 2019 some was moved to "9C" TSMC Singapore pursuant to PCN MDG/19/10803

[Tesla DeLorean]

Any observation in the Markings or IDCODE for the older working ones?

This might help narrow down the production date / window, and a source for the wafers.

Other things that might change over time is the System Memory / Boot Loader version, although I don't perceive that as impacting LSE in any way.

[Tesla DeLorean]

The errata seems less stale, but only covers the 0x2000 device

https://www.st.com/resource/en/errata_sheet/es0202-stm32f051x4x6x8-device-errata-stmicroelectronics.pdf

But nothing about LSE