Kontron COMe-mSP1 - Manual (Page 44)

COMe-mSP1 / Features and Interfaces
4.17 SDIO
The SD card standard is a standard for removable memory storages designed and licensed by the SD Card Association
(
http://sdcard.org ). The card form factor, electrical interface, and protocol are all part of the SD Card specification. The
Intel® System Controller Hub US15W supports up to 3 SDIO interfaces. On nanoETXexpress-SP the first interface SDIO#0
(4-bit wide) is shared with the module GPIO signals. The integrated SDIO 1.1/MMC 4.1 controller in US15W only supports
byte-address mode for SDIO storage cards up to 2GB. Sector-addressing and SDHC is not supported.
» MMC 4.1 transfer rates can be up to 48MHz and bus widths of 1, 4 or 8 bits
» SDIO 1.1 supports transfer rates up to 24MHz and bus widths of 1 or 4 bits
The following table shows which GPIO-ports can be used for the SD-card interface:
General purpose Input/output SD card interface signals
GPI0 SLOT0_DATA0
GPI1 SLOT0_DATA1
GPI2 SLOT0_DATA2
GPI3 SLOT0_DATA3
GPO0 SLOT0_CLK
GPO1 SLOT0_CMD
GPO2 SLOT0_WP
GPO3 SLOT0_CD#
The SD_CMD line needs a pull-up resistor that can vary depending on the length of the
electrical paths (typical from 10kOhm to 100kOhm).
The maximum length for SDIO signals on the baseboard should be 80mm.
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