STM32U575 Fails to init SD Card

[sethkaz]

I'm working on getting a minimum viable example functional using a U575 IC and a micro SD Card.  The hardware I'm using is the Nucleo-U575 board along with an SD Card breakout from Adafruit. I've wired it up as an SDIO 4-bit setup.  

With just the autogenerated code when I enable the SDMMC peripheral, I'm finding that it runs into an error.  

HAL_SDIO_Init() -> SDIO_InitCard() -> SDMMC_CmdSendOperationcondition() -> SDMMC_GetCmdResp4() returns a errorstate of 4 (SDMMC_ERROR_CMD_RSP_TIMEOUT).  What is timing out here?  

Is there something I need to do to set the SD Card into SDIO mode? 

Also, the SDIO_CLK looks to be running non-stop at ~800kHz.  Is this normal? I would expect it to run only when something it happening on the bus (just like SPI), but this is my first foray into SDIO.

This is using STM32CubeIDE 1.19.0 with the latest firmware pack (I installed it and it downloaded it today)

[Saket_Om]

Hello @sethkaz 

Please refer to the example below: 

STM32CubeU5/Projects/STM32U575I-EV/Examples/SD/SD_ReadWrite_DMALinkedList at main · STMicroelectronics/STM32CubeU5 · GitHub