Clock Configuration feature stuck (trying to find a solution in an endless cycle)

[Ivan Slivin]

The only HCLK frequency possible is 40MHz (ofcourse i need higher freq)

Please help me resolve this.

[Khouloud OTHMAN]

Hello @Ivan Slivin​ ,

First let me welcome you to the STM32 Community ��

Thanks for having reported, but I'm unable to reproduce the issue from my side. I can increase the HCLK frequency without problems.

It will be more helpful to attach your .ioc file for further check.

Thanks in advance,

Khouloud.

[Ivan Slivin]

Hi Khouloud, Thank you for the prompt response. Please try my project (attached)

[Ivan Slivin · Accepted solution]

I have solved it. The issue was: CubeMx could not find proper PLL setup for SDMMC and USB unit. I've made it manually.

[Khouloud OTHMAN]

Hi @Ivan Slivin​ ,

Glad that your problem is resolved ��

In fact, sometimes STM32CubeMX is not able to resolve automatically some clock issue specially for the somewhat complex clock tree as the case of STM32F746VGTx.

As you have already mentioned the endless search for solution is due to the fact that CubeMx could not find proper PLL setup for SDMMC and USB unit.

The USB OTG FS requires a 48 MHz clock to work correctly. The SDMMC need a frequency lower than or equal to 48 MHz to work correctly.

More details about clock configuration can be found in the STM32F74xxx Reference Manual.

Do not hesitate to raise any problem/ feedback.

Khouloud.