3.4.10 Secure Digital Multimedia Card

The SD (Secure Digital) Card is a non-volatile memory card format used as a mass storage memory in mobile devices.

The SAMA7G54-EK has one Secure Digital Multimedia Card (SDMMC) interface that supports the MultiMedia Card (e.MMC) specification V4.51, the SD Memory Card specification V3.0, and the SDIO V3.0 specification. It is compliant with the SD Host Controller Standard V3.0 specification.

A standard MMC/SD Card connector, connected to the SDMMC interface, is mounted on the top side of the board. The SDMMC0 communication is based on an 8-pin interface (clock, command, four data and power lines). It includes a card detection switch.

Figure 3-48. SD Card Interface Schematic

The table below describes the pin assignment of SD/MMC connector J4.

Table 3-39. Standard SD Socket J4 Pin Assignment Signal Descriptions
FunctionPinPIOSignal Description
SD Card data line 31PC2SDMMC1_DAT3_PC2
SD Card command line2PB29SDMMC1_CMD_PB29
Ground3Ground
3.3V SD Card supply4VDD_SDCARD (3.3V)
SD Card clock line5PB30SDMMC1_CK_PB30
Ground6Ground
SD Card data line 07PB31SDMMC1_DAT0_PB31
SD Card data line 18PC0SDMMC1_DAT1_PC0
SD Card data line 19PC1SDMMC1_DAT2_PC1
SD Card card detect10PC4SDMMC1_CD_PC4
SD Card write protect11PC3SDMMC1_WP_PC3
Ground12Ground

SDMMC data and control lines can be 3.3V or 1.8V, depending on the SD Card speed. A power voltage selector is implemented and controlled by pin PC5 of the MPU. The voltage selected by default is 3.3V.

Figure 3-49. SD Card Power Selector Schematic

The user can perform a hard reset of the SD Card by forcing the PB28 PIO of the SAMA7G5 device or by using the processor reset line (R262 must be populated) "NRST_OUT" signal.

This action disables the MIC94085YFT power switch and VDD_SDCARD is forced to ground. For more details about the MIC94085YFT power switch, refer to the product web page.

Figure 3-50. SD Card Reset Schematic

The table below describes the pin assignment of the SD/MMC interface.

Table 3-40. SD/MMC Pin Assignment
PIOSignal NameShared WithSignal Description
PB28SDMMC1_RSTN_PB28SD Card reset signal
PB29SDMMC1_CMD_PB29SD Card command line
PB30SDMMC1_CK_PB30SD Card clock signal
PB31SDMMC1_DAT0_PB31SD Card data line 0
PC0SDMMC1_DAT1_PC0SD Card data line 1
PC1SDMMC1_DAT2_PC1SD Card data line 2
PC2SDMMC1_DAT3_PC2SD Card data line 3
PC3SDMMC1_WP_PC3SD Card connector write protect signal
PC4SDMMC1_CD_PC4SD Card card detect
PC5SDMMC1_1V8SEL_PC5SD Card signal voltage selection
NRST_OUTNRST_OUTMicroprocessor reset output