Using SD card on nRF9161 DK

[JOEBRE]

Hello, we've a nRF9161 DK board a we saw on the back side a footprint for mounting an SD card holder and we found the SD card holder component in the BOM.

Unfortunately there is no mention about the usage of the SD card in for the nRF9161 DK anywhere in the documentation.

Is there any problem on using the SD card on nRF9161 DK (trough SPI I guess) ?

What do we have to do to connect the SD card to the nRF9161 module (excluding the soldering of the card holder)?

Thanks in advance for the support,

Joel

[JOEBRE]

Hello... before using the SD card.(mount it and write/read to it) I've to format it ... isn't it ?

The SD card gets now properly detected (disk_access_init):

*** Booting nRF Connect SDK v3.0.2-89ba1294ac9b ***
*** Using Zephyr OS v4.0.99-f791c49f492c ***
[00:00:00.252,471] <dbg> sd: sd_init_io: Host controller support 3.3V max
[00:00:00.252,471] <dbg> sd: sd_init_io: Resetting power to card
[00:00:00.256,195] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd0 arg 0x0
[00:00:00.256,988] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd8 arg 0x1aa
[00:00:00.257,751] <dbg> sd: sd_send_interface_condition: Found SDHC with CMD8 support
[00:00:00.257,781] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd59 arg 0x1
[00:00:00.258,544] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd58 arg 0x0
[00:00:00.259,429] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd55 arg 0x0
[00:00:00.260,223] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd41 arg 0x40000000
[00:00:00.271,087] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd55 arg 0x0
[00:00:00.271,881] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd41 arg 0x40000000
[00:00:00.272,644] <dbg> sd: sdmmc_send_ocr: SDMMC responded to ACMD41 after 1 attempts
[00:00:00.272,674] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd58 arg 0x40000000
[00:00:00.273,468] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd10 arg 0x0
[00:00:00.274,902] <dbg> sd: card_read_cid: Card MID: 0x3, OID: DS
[00:00:00.274,932] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd9 arg 0x0
[00:00:00.276,397] <dbg> sd: sdmmc_read_csd: Card block count 7744512, block size 512
[00:00:00.276,397] <inf> sd: Maximum SD clock is under 25MHz, using clock of 1000000Hz
[00:00:00.276,428] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd55 arg 0x0
[00:00:00.276,977] <dbg> sdhc_spi: sdhc_spi_send_cmd: cmd51 arg 0x0
[00:00:00.277,740] <dbg> sd: sdmmc_read_scr: SD reports specification version 8
[00:00:00.277,770] <inf> littlefs: LittleFS version 2.9, disk version 2.1

but I get an error calling:

#define MKFS_FS_TYPE FS_LITTLEFS
#define MKFS_DEV_ID "SDCard"
#define MKFS_FLAGS 0

 fs_mkfs(MKFS_FS_TYPE, (uintptr_t)MKFS_DEV_ID, NULL, MKFS_FLAGS);

[00:00:00.277,770] <err> littlefs: Can't init littlefs backend, review configs and flags 0x00000000
[00:00:00.277,770] <err> fs: mkfs error (-134)

My .conf is:

CONFIG_DISK_ACCESS=y
CONFIG_DISK_DRIVERS=y
CONFIG_DISK_DRIVER_SDMMC=y

CONFIG_DEBUG=y
CONFIG_LOG=y
CONFIG_LOG_MODE_MINIMAL=n

CONFIG_FILE_SYSTEM=y
CONFIG_FILE_SYSTEM_LITTLEFS=y
CONFIG_FILE_SYSTEM_MKFS=y

CONFIG_FS_LITTLEFS_BLK_DEV=y
CONFIG_FS_LITTLEFS_FMP_DEV=n

Is there something missing ? how shall i call fs_mkfs in order to format the SD card ?

The USB mass storage code sample do not helps me a lot in the understanding on how to make the connection between  LittleFS and the file system to the sd card driver ... 

Is there anything missing the dts overlay (like partitions ... )?  Sorry it may be a stupid question but I'm really new to Zephyr and the understanding is not immediate to me (if I understood it corectly mass storage sample supports only FAT as fs for  SD card and not LittleFS on SD card).

Thx, Joel