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May 11, 2025
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FMC SDRAM common clock description mismatch between CubeIDE and RM0433

  • May 11, 2025
  • 1 reply
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I want to set up 100MHz for SDRAM.

STM32CubeIDE version 1.18.1 has the following options for SDRAM clock:

gabrielgcma_0-1746991598437.png

The selected board is the STM32H743IITx. 

RM0433 Rev 8 states that:

gabrielgcma_1-1746991680421.png

I'm not sure HCLK and fmc_ker_ck are the same thing.

If I have my FMC clock set up as:

gabrielgcma_2-1746991712461.png

And select HCLK/2, I'll have 100MHz for the SDRAM? Or is HCKL system clock?

gabrielgcma_3-1746991843135.png

 

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Best answer by TDK

> And select HCLK/2, I'll have 100MHz for the SDRAM?

Short answer: yes.

 

HCLK means fmc_ker_ck here.

 

If you go through HAL to see what the setting affects, you see it affects this field:

TDK_0-1747006331417.png

 

Do a search for fmc_ker_ck and you see where that's from. For you, it's PLL2R.

TDK_1-1747006420056.png

 

1 reply

TDK
TDKBest answer
May 11, 2025

> And select HCLK/2, I'll have 100MHz for the SDRAM?

Short answer: yes.

 

HCLK means fmc_ker_ck here.

 

If you go through HAL to see what the setting affects, you see it affects this field:

TDK_0-1747006331417.png

 

Do a search for fmc_ker_ck and you see where that's from. For you, it's PLL2R.

TDK_1-1747006420056.png

 

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