SD card on an STM32U5G9J-DK1 Discovery Kit

[Andrei Chichak]

I'm trying to graft an SD card onto the U5G round display development board.  CN9 brings out all of the control and data lines for SDMMC2.

The problem that I am seeing is that the SD device will not initialize (MX_SDMMC2_Init) due to a timeout in HAL_SD_Init -> HAL_SD_InitCard -> SD_powerON -> SDMMC_CmdGoIdleState

Currently I have VCC to the card plugged into 3V3, ground, clock, and 47K pull-ups to VCC on CMD and the 4 data lines.

I've tried using level shifters to use the 1V8 signalling on the processor side and 3V3 signalling on the SD card side, 4-bit SD, 4-bit SDIO, 1-bit SD, and 1-bit SD with the signals simply pulled up to 3V3. All give the same result, timeout on Go-Idle-State.

The card is formatted and works properly on a PC. I've got test programs on a F479 Discovery board working with SD cards under FileX, and I tried making the hookup as close as possible to a U575 EV or the 429 Disco, but this U5 is not cooperating.

Given that this board uses 1V8 levels and SD cards use 3V3 to start, is it reasonable to pull-up the lines to 3V3 and expect the SDMMC peripheral to work?

[Andrei Chichak]

I suppose I should mention: MacOS 15.3.1, STM32CubeIDE 1.18.0, STM32Cube FW_U5 V1.7.0

[AScha.3]

SD-cards only working on 3v3 supply (and signal levels - except switching to UHS mode later ).

+

from U575 ds:

so minimum for U575 seems 2v7 , and emmc can go with lower supply:

So just try with 3v3 supply: sd-interface working then ?

[Andrei Chichak]

Alright, this is weird. If I look into the SFRs for SDMMC2, the value of POWER is 0, the power is turned off, even though the init functions turn it on.

If  I trace through the code, HAL_SD_Init -> HAL_SD_InitCard -> SDMMC_PowerState_ON sets the register thus:

  SDMMCx->POWER |= SDMMC_POWER_PWRCTRL;

Which should set POWER to 3, but it doesn't stick, actually all of the registers in the SDMMC2 device are zeros. (start location 0x420C'8C00).

It's like the peripheral isn't being clocked.

I'll attach my .ioc file, it has very little in it.

[Andrei Chichak · Accepted solution]

But if I manually change the value of RCC_AHB2ENR1.SDMMC2EN to 0x1, then the  power can be turned  on.

Oh, I see, HAL_SD_MspInit calls:

__HAL_RCC_SDMMC1_CLK_ENABLE();

instead of:

__HAL_RCC_SDMMC2_CLK_ENABLE();

ST, please fix this.

[Andrei Chichak]

Yes, the answer to the original question is that, even with pull-ups to 3V3, you need a voltage translator to put an SD card onto the DK1. The processor is being run from 1V8 and that will have CLK running at 1V8, which is too low for the SD card to cope. Putting on a level shifter, such as an NXP NVT4858 will bring all of the signals into line.

BUT the clock still isn't turned on due to an error in the HAL. 

[Mike_ST]

Hello,

thank you for the feedback:

Internal ticket:

#204951