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OSD3358-SM-RED
– User Guide
Rev. 1.0 9/19/2017
Octavo Systems LLC
Copyright 2017
4.10
MicroSD card slot
Figure 50: OSD3358-SM-RED micro-SD card slot circuit
Figure 50 shows the MicroSD card slot X3 connected to the processor on MMC0 interface on
the OSD3358-SM Evaluation Board schematic. This slot can be used to boot the board from a
microSD card, to flash the on board eMMC or as a normal storage device. Unlike MMC1, this is
a 4 bit interface which can cause it to be slower than the eMMC interface. Similar to the MMC1
interface, the SD card interface also has a CLK and a CMD line. The MMC0_CD is a card
detect signal that is pulled down when a microSD card is inserted and so, the processor is
aware of the card when it is. Pull up resistors are used here as well to increase rise times and
compensate for board capacitance. More information on booting of the board and board
software can be found in Section 5.
