User`s guide

Adding Support for the i.MX53 ESDHC
i.MX53 System Development User’s Guide, Rev. 1
15-6 Freescale Semiconductor
15.3.1 ESDHC Interface Features
The ESDHC has 15 associate I/O signals with the following functions.
• The SD_CLK is an internally generated clock used to drive the MMC, SD, SDIO cards.
• The CMD I/O is used to send commands and receive responses to/from the card. Eight data lines
(DAT7–DAT0) are used to perform data transfers between the ESDHC and the card.
• The SD_CD# and SD_WP are card detection and write protection signals directly routed from the
socket. A low on SD_CD# means that a card is inserted and a high on SD_WP means that the write
protect switch is active.
• SD_OD is an output signal generated in SoC level outside ESDHC and is used to select the external
open drain resistor.
• SD_LCTL is an output signal used to drive an external LED to indicate that the SD interface is
busy.
SD_CD#, SD_WP, SD_OD, SD_LCTL are all optional for system implementation. If the ESDHC is
configured to support a 4-bit data transfer, DAT7–DAT4 can also be optional and tied to high.
15.3.2 ESDHC Operation Modes Supported by the i.MX53
The ESDHC acts as a bridge, passing host bus transactions to the SD/SDIO/MMC cards by sending
commands and performing data accesses to/from the cards. It handles the SD/SDIO/MMC protocols at the
Table 15-2. ESDHC Pins
Pin Function
SD_CLK Clock for MMC/SD/SDIO card
SD_CMD CMD line connect to card
SD_DAT7 DAT7 line in 8-bit mode - Not used in other modes
SD_DAT6 DAT6 line in 8-bit mode - Not used in other modes
SD_DAT5 DAT5 line in 8-bit mode - Not used in other modes
SD_DAT4 DAT4 line in 8-bit mode - Not used in other modes
SD_DAT3 DAT3 line in 4/8-bit mode or configured as card detection pin. May be configured as card detection pin
in 1-bit mode
SD_DAT2 DAT2 line or Read Wait in 4-bit mode. Read Wait in 1-bit mode
SD_DAT1 DAT1 line in 4/8-bit mode. Also used to detect interrupt in 1/4-bit mode
SD_DAT0 DAT0 line in all modes. Also used to detect busy state
SD_CD# Card detection pin. If not used tie high
SD_WP Card write protect detect. If not used tie low
SD_OD Open drain select (not generated within the ESDHC). Optional output
SD_LCTL LED control used to drive an external LED. Active high. Fully controlled by the driver. Optional output
SD_VS Control the voltage on SD pads to be high voltage (around 3.0V) or low voltage (around 1.8 V). 0 stands
for low voltage range optional output.