Alternative Gpio Use For Sdio Interface; Sdio Pin Description - Kontron COM Express Extension Specification

5.2.1

Alternative GPIO use for SDIO Interface

Pin GPIO SDIO
A54 GPI0 DATA0
A63 GPI1 DATA1
A67 GPI2 DATA2
A85 GPI3 DATA3
A93 GPO0 CLK

SDIO Pin description

Signal Type
SD_DATA[3:0] I/O
CMOS3.3
SD_CMD I/O
CMOS3.3
SD1_CLK O
CMOS3.3
SD0_WP I
CMOS3.3
SD1_CD# I
CMOS3.3
Copyright © COM Express™ Extension
Specification Rev 013
Pin GPIO SDIO
B54 GPO1 CMD
B57 GPO2 WP
B63 GPO3 CD#
Description
SDIO Controller 0/1/2 Data: These signals operate
in push-pull mode. The SD card includes internal pull-
up resistors for all data lines. By default, after power-
up, only SDn_DATA0 is used for data transfer. Wider
data bus widths can be configured for data transfer.
SDIO Controller 0/1/2 Command: This signal is
used for card initialization and transfer of commands.
It has two operating modes: open-drain for
initialization mode, and push-pull for fast command
transfer.
SDIO Controller 0/1/2 Clock: With each cycle of this
signal a one-bit ransfer on the command and each
data line occurs.
This signal is generated by Intel SCH at a maximum
frequency of:
24 Mhz for SD and SDIO.
48 Mhz for MMC.
SDIO Controller 0/1/2 Write Protect: These signals
denote the state of the write-protect tab on SD cards.
SDIO Controller 0/1/2 Card Detect: Indicates when
a card is present in an external slot.
17
5 Hardware extensions