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Pavel A.
Pavel A.Best answer
Mar 31, 2021 11:34 PM UTC

> The maximum core frequency l can get is 96MHz compared to 400 MHz in the example.

This is a known issue. As too often with this forum, it's easier to reply again than search for the original answer.

Go to RCC parameters and select voltage scale 0. Then it will let you have 400 MHz.

0693W000008ySimQAE.png 

> none of the ST provided board examples using BYPASS mode.

Nucleo boards use BYPASS mode (at least some of them), and all Cube examples for these boards naturally use BYPASS mode.

-- pa

4 replies

Tesla DeLorean
Guru
Mar 31, 2021 10:47 PM UTC

None of the board examples use BYPASS mode, not sure the logic there.

Make sure HSE_VALUE is 25000000 in the stm32h7xx_hal_conf.h file

Use the SystemClock_Config() from

STM32Cube_FW_H7_V1.8.0\Projects\STM32H745I-DISCO\Applications\FatFs\FatFs_Shared_Device\CM7\Src\main.c

https://www.st.com/content/ccc/resource/technical/layouts_and_diagrams/schematic_pack/group1/e3/ee/b5/14/fe/97/43/3d/MB1381-H745XI-B02_Schematic/files/MB1381-H745XI-B02_Schematic.pdf/jcr:content/translations/en.MB1381-H745XI-B02_Schematic.pdf

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DWill.4
DWill.4Author
Associate II
Mar 31, 2021 11:13 PM UTC

Thank you for replying.

You are correct about none of the ST provided board examples using BYPASS mode. I was trying to implement the user created example in the link. Your advice will set the core to 400MHz. What is your opinion on the linkerscript?

Pavel A.
Pavel A.Best answer
Mar 31, 2021 11:34 PM UTC

> The maximum core frequency l can get is 96MHz compared to 400 MHz in the example.

This is a known issue. As too often with this forum, it's easier to reply again than search for the original answer.

Go to RCC parameters and select voltage scale 0. Then it will let you have 400 MHz.

0693W000008ySimQAE.png 

> none of the ST provided board examples using BYPASS mode.

Nucleo boards use BYPASS mode (at least some of them), and all Cube examples for these boards naturally use BYPASS mode.

-- pa

Piranha
Principal III
Apr 2, 2021 8:18 AM UTC

Clive is right:

https://github.com/STMicroelectronics/STM32CubeH7/blob/ccb11556044540590ca6e45056e6b65cdca2deb2/Projects/STM32H745I-DISCO/Applications/FatFs/FatFs_Shared_Device/CM7/Src/main.c#L281

The value assigned should have been RCC_HSE_BYPASS. Well, that's just one of countless bugs in STM32 broken bloatware.