Interface UHS-ii micro SD-card reader on custom board?


We are designing a custom carrier board for the Jetson Nano Production Module. We wish to add a micro SD memory card reader to our board that can utilize the UHS-ii protocol and therefore allow faster read/write speeds to the card when using a UHS-ii capable card. We understand that the Nano has SDHOST version 4.0, which supports UHS-ii, but on the pinout for the Nano module we see only SDMMC_DAT0, SDMMC_DAT1, SDMMC_DAT2 and SDMMC_DAT3. These pins match the requirements for UHS-i, and are connected to the card reader on the dev-kit Nano, but the UHS-ii reader has two extra differential data lines and one differential clock line (see attached image showing pinout of the UHS-ii card reader). To which pins on the Nano module should these lines be connected ? Is there an alternative way of connecting the UHS-ii card reader, using e.g. SPI ? (We are already using the USB-SS interface for another peripheral)



Please refer to nano module datasheet in DLC which indicates that “Support for SD 4.0 Specification without UHS-II”.

OK, thanks.