View source for IoTGateway/BSP/Android/Gettingstarted/How to use SD/MMC Card for rk

== Browse the SD ==

Android 6 Marshmallow also includes a&nbsp;built-in file manager feature to browse the SD card.

*Launch the&nbsp;'''Settings'''&nbsp;app.
*Tap on&nbsp;'''Storage & USB'''.
*Tap on&nbsp;'''SD card '''to explore the files.

[[File:Sd-4680.png|RTENOTITLE]]

[[File:Sd2-4680.png|RTENOTITLE]]

[[File:Sd1-4680.png|RTENOTITLE]]



External storage (SD/MMC card) is managed by a combination of the&nbsp;<code>vold</code>&nbsp;init service and&nbsp;<code>MountService</code>&nbsp;system service. Mounting of physical external storage volumes is handled by&nbsp;<code>vold</code>, which performs staging operations to prepare the media before exposing it to apps. Please refer to "Device Configuration" section on the Andrid website&nbsp;[http://source.android.com/devices/storage/config.html http://source.android.com/devices/storage/config.html]

== fstab.device ==
<pre>/devices/ff0c0000.rksdmmc/mmc_host*&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; auto&nbsp; auto&nbsp;&nbsp;&nbsp; defaults&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; voldmanaged=sdcard1:auto,encryptable=userdata
</pre>

== Check sysfs node ==
<pre># cat /sys/block/mmcblk0/device/type
MMC
# cat /sys/block/mmcblk1/device/type
SD
</pre>



== SD/MMC Card insertion ==

The kernel starts scanning once the SD card is inserted and&nbsp;create devices for each partition.&nbsp;
<pre>rk_sdmmc: BOOT&nbsp;&nbsp; The card is inserted.&nbsp; ===!!!!!!==[mmc1]
mmc_host mmc1: Bus speed (slot 0) = 50000000Hz (slot req 400000Hz, actual 396825HZ div = 63)
rk_sdmmc: BOOT dw_mci_setup_bus: argue clk_mmc workaround out 800000Hz for init[mmc1]
mmc_host mmc1: Bus speed (slot 0) = 50000000Hz (slot req 50000000Hz, actual 50000000HZ div = 0)
rk_sdmmc: BOOT dw_mci_setup_bus: argue clk_mmc workaround out normal clock [mmc1]
rk_sdmmc: BOOT Bus speed=50000000Hz,Bus width=4bits.[mmc1]
mmc1: new high speed SDHC card at address 1234
mmcblk1: mmc1:1234 SA04G 3.63 GiB
&nbsp;mmcblk1: p1
FAT-fs (mmcblk1p1): Volume was not properly unmounted. Some data may be corrupt. Please run fsck.
</pre>

== Write to SD ==
<pre># dd if=data of=/dev/block/mmcblk1 bs=1 seek=4096
</pre>

== Read from SD ==
<pre># dd if=/dev/block/mmcblk1 of=data1 bs=1 count=1024 skip=4096
</pre>