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load2005
load2005
Associate III
April 4, 2025
Question

CubeMX+SD card 4 bit+STM32F796 DISCO SD_FindSCR problem

  • April 4, 2025
  • 3 replies
  • 481 views

HI All,

I am using STM32F769 DISCO board.
I have configured SD card in 1 bit moe and it works fine.
But it doesn't work in 4 bit mode.
The problem is in SD_FindSCR function.

if(__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_RXDAVL))

is never executed.
Cube MX version is 6.8.1

I see there are many similar post's on the forum but
none of the solution worked.
I have set the clock to 12Mhz and I see that
HAL initialize sd card with 1 bit line then trying to read SCR
register to check if 4 bit data line is supported.
And can't read SCR register.
Maybe there are fixes to this HAL library?
Thanks,

3 replies

STTwo-32
STTwo-32
Technical Moderator
April 4, 2025

Hello @load2005 

Could you please try using the STM32CubeMX V6.14.0 and the STM32CubeF7 V1.17.2.

Best Regards.

STTwo-32

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load2005
load2005Author
Associate III
April 5, 2025

Hello,

 

I have updates to CubeMx V6.14 and checked that I am using F7 V1.17.2.

The problem is still the same.

This part is hit when reading SCR register

 

else if(!__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_RXACT))
{
break;
}

 

Can you confirm the problem with your setup please?

K
KK3
Visitor II
April 28, 2025

Same issue with STM32F746NGHx, FW V1.17.2.

A logic analyzer shows that the SD card is responding, but the SDMMC_FLAG_RXDAVL flag is never set. Adding some delay in between doesn't change the situation.

load2005
load2005Author
Associate III
May 8, 2025

Hi ALL

I have fixed the issue.

The problem was that SD was initialized in 4 bit mode but before checking 4bit mode availability

it must be initialized in 1 bit mode.

I had to dig through a code mess to find the problem.

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