SPEED_CLASS_CONTROL in SPI write sequence

[tommy]

Dear sires,

Would it be possible to let you answer the following question?

In nRF5340 SDK, does it use CMD20"SPEED_CLASS_CONTROL " in SPI write sequence to ensure minimum interoperability withs multiple SD cards?

Under our product's development, we have found the write sequence have failed in some type of SD card.

BR,

[Kazi Afroza Sultana]

Hello,

You can see this sample sdk-zephyr/subsys/sd/sdmmc.c at 3d2f1c7f0558d76b24afdabbaff6d36ea96db768 · nrfconnect/sdk-zephyr · GitHub to know how speed class command is used

/* Check if card supports speed class command (CMD20) */
	if (card_scr.cmd_support & 0x1U) {
		card->flags |= SD_SPEED_CLASS_CONTROL_FLAG;
	}
	/* Check for set block count (CMD 23) support */
	if (card_scr.cmd_support & 0x2U) {
		card->flags |= SD_CMD23_FLAG;
	}
	return 0;