Compaq Extension manual Alternative Gpio use for Sdio Interface, Sdio Pin description

Signal

Type

Description

SD_DATA[3:0]

I/O

SDIO Controller 0/1/2 Data: These signals operate

CMOS3.3

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.

SD_CMD

I/O

SDIO Controller 0/1/2 Command: This signal is

CMOS3.3

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.

SD1_CLK

O

SDIO Controller 0/1/2 Clock: With each cycle of this

CMOS3.3

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.

SD0_WP

I

SDIO Controller 0/1/2 Write Protect: These signals

CMOS3.3

denote the state of the write-protect tab on SD cards.

SD1_CD#

I

SDIO Controller 0/1/2 Card Detect: Indicates when

CMOS3.3

a card is present in an external slot.