OLIMEX© 2015
A13-SOM user's manual
6.2.1 SD/MMC slot
The schematic related to the SD/MMC (microSD connector) is shown below:
SD/MMC slot is a microSD card slot connector, located on the top of the board.
This slot is typically used for booting the OS, due to the larger capacities of the microSD cards
(compared to SD or MMC cards). It is suggested to have an SD card with a proper Linux/Android
image especially if you have ordered a version of the board without NAND memory. It is also
recommended to use Class 10 (10MByte/sec) card for faster read/write operations, lower class cards
(especially higher capacity ones) might slow down the whole system.
The table with the microSD card signals might be found below:
SD/MMC1 connector
Pin # Connector signal name
Wire name (processor pin number)
1 DAT2/RES
SDC0_DATA2 (113)
2 CD/DAT3/CS
SDC0_DATA3 (112)
3 CMD/DI
SDC0_CMD (111)
4 VDD
SD_VCC
5 CLK/SCLK
SDC0_SCLK (110)
6 VSS
GND
7 DAT0/DO
SDC0_DATA0 (108)
8 DAT1/RES
SDC0_DATA1 (107)
9 CARD DETECT(SYMBOL)
SD0CARD-DETECT (155)
13 GND
GND
6.3 Power pins for external power supply
There are two power pins suitable for powering the board. These are located on different places of
A13-SOM – one at the UART1 connector, the other on GPIO1 connector. To power the board you
need to provide 3.3V to one of them. You can use any of the pins or the pinholes named GND.
The required current may vary depending on the peripherals connected to the board. The power
supply should be capable of providing at least 0.5A of current.
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