How to change the (STLINK_V3E) MCO HSE Frequency

[O.Elsherif]

That is the ST-link V3 on NUCLEO-H755ZI board.

The HSE MCO option is set to HSE/3, how to change it to HSE/5.

Usually this is configurable in code, but this is ST-link firmware. If there is a way to change the division value, please some one let me know.

[S C · Accepted solution]

Hello,

Sorry for having missed this topic. The ability to change the MCO source on STLINK-V3E boards has been added in response to another topic: ST-LINK provides 8.08 MHz instead of 8.000 on new ... - Page 3 - STMicroelectronics Community. It has been documented in RN0093 rev23 (11 may 20) and remains in the history of more recent versions. The impact on all other boards UM has been missed, concerning the UM2408 it's all the more a pity as it has been updated afterwards for other things (23 march 21) ...
Technically at that time the aim of the change was to increase the accuracy of the clock, and it has been decided (mainly for graphical interface simplification reason), to provide only a single value based on the HSE, close to the initial 8MHz, and hoping that an additional factor of 24/25 in the PLL could address most cases. We also decided to change the oscillator of the STLINK-V3EC boards back to 24MHz to fix the issue on future boards.
For this case especially, I think we will add the HSE/5 selection in STLink-Upgrade applications. I'm wondering also about the HSE/4 which could also allow other "high" frequency multiples.

[Piranha]

For this case especially, I think we will add the HSE/5 selection in STLink-Upgrade applications. I'm wondering also about the HSE/4 which could also allow other "high" frequency multiples.

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Just put there a combo box with all (1..5) MCO divider values.

@Amel NASRI , why did you selected this post as a "solution", while the actual issue (fixing the documentation) has not been done? The post even explicitly emphasizes it:

The impact on all other boards UM has been missed, concerning the UM2408 it's all the more a pity as it has been updated afterwards for other things (23 march 21) ...

[Amel NASRI]

Hi @Piranha ,

I selected the post of @S C as a solution because I assess that it answers the initial question.

I'm sure that the documentation & tool enhancements will be handled properly by @S C and they raised as results of this discussion.

-Amel 

[Piranha]

The facts speak against it...

https://community.st.com/t5/stm32-mcus-embedded-software/ethernet-send-complete-interrupt-not-triggered-in-stm32f7/m-p/320871

Imen "took care" of this topic 4 years ago and still almost nothing has been done!

[Piranha]

The impact on all other boards UM has been missed, concerning the UM2408 it's all the more a pity as it has been updated afterwards for other things (23 march 21) ...

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UM2407 Rev 4 updated at 12-Oct-2023 and still this issue is not corrected. Good job!

[ASche.5]

I am confused how can this be done and changed in the V3 on Nucelo board that do not have a 8MHz base is there only the firmware update tool ? What else I just started with STM32H7 that has 25MHz base clock and I measure regardless of the settings in the firmwar tool som 17.somthing MHz at SB72 this is a MESS. Please can some one explain what is going on??!? 

[S C]

Hello,

Initially boards have been produced with a single MCO output value: 8MHz, generated from the internal HSI of the STM32F723. Afterwards, several versions of ST-Link firmware have been published to extend this behavior; the last modification is available since V3J14M5 and allows several derivative values from the ST-Link 25MHz HSE additionally to the 8MHz HSI (selection is possible during the ST-Link firmware update). Concerning your point regarding SB72, please precise the board references and please also double check with the most recent ST-Link firmware version (STSW-LINK007 - ST-LINK, ST-LINK/V2, ST-LINK/V2-1, STLINK-V3 boards firmware upgrade - STMicroelectronics). If you changed something regarding SB configuration since board out of the box, please double check that the MCO from ST-Link is not conflicting with another feature. You might also check against a possible conflict with the running application

[ASche.5]

Thanks for the hints and summery of the HSE options on the nucleo board. The problem that I faced was that I measured something obscure like 6-7MHz on the SB72 jumper. But after updating the ST-Link again I had 8MHz clock but a jitterd  one, this was one the  HSI of the F733. Now on the HSE the 8.33 are stable enogh but force me to have fracrtions in the PLL of the STM32H7. I guess its fine for the moment and I will upgrade my nucleo to have a HSE crystal in future.