Using a MicroSD Card

An SD card is a flash memory device that uses quantum tunneling effects to store information. Sort of like locking a piece of iron a secure glass box, and using a magnet to move it around to store information. The smallest version of the SD card available right now is the MicroSD format.

MicroSD Card

The Omega2+ comes with a MicroSD card slot, enabling you to greatly expand the storage capacity of the Omega without much added cost. The MicroSD card slot on the Omega2+ can be found at the bottom of the board inbetween the pins.

MicroSD Card Slot Location

We’ll cover how to insert the SD card, how storage devices work in Linux, how to work with files on the card, and how to safely remove it without damaging your data.

Note: The Omega2+ supports MicroSD card on firmware builds b143 and higher. Always remember to upgrade to the latest firmware when working with SD cards!

Inserting a MicroSD Card

The MicroSD slot is spring loaded, and it will remain in place once it’s locked in. to properly seat it,

MicroSD card sitting the slot

To insert the MicroSD card, you should firmly push the SD card into the slot until you hear and feel a click.

Push it in firmly

This is what it should look like once seated properly -

MicroSD properly locked in slot

After you insert the card, you should make sure it’s mounted in the filesystem and accessible.

Occasionally, the spring mechanism may be already preloaded and your card will pop right back out if you let go. Simply pushed it back in until the click, and you should be all set.

If you’re running the latest firmware, the Omega should have automatically mounted the MicroSD card already.

Storage Devices and Linux

On a Linux device, a storage device needs to be mounted in order to access the data. Mounting a device maps its storage space to a directory on your device so that you may access it.

The Omega2 comes ready with an auto-mounting tool that will take care of that process for you!

The default mount location is /mnt/.

On firmware older than v0.3.0, the default mount location was /tmp/mounts/ and the mountd package controlled automatic mounting. Firmwares v0.3.0 and up use the block-mount package.

Accessing the MicroSD Card

Under normal circumstances, the SD card and any USB device you plugged in should be the only things that exist in the /mnt directory. Thus you can check there with ls /mnt/ to determine the name the Omega assigned the card. Running ls /mnt gave us mmcblk0p1 as the name of our MicroSD card.

Once mounted, it acts as a regular directory or folder in all ways, and any file that you stored in the card originally should be there! For us, it looked something like this:

root@Omega-1234:~# cd /mnt
root@Omega-1234:/mnt# ls

The p1 in the name means partition number 1 of the MicroSD card, if you have partitioned your MicroSD, they should show up as mmcblk0p1, mmcblk0p2, and so on.

If you’d like to change where the MicroSD card is mounted on the filesystem, we’ve written a guide covering how to do so for both MicroSD cards and USB drives.

Safely Removing a MicroSD Card

To safely remove your SD card you should always unmount it first. This will eliminiate the possibility of the data being accessed while you physically remove it, which can corrupt the SD card’s data and filesystem.

The umount command is used to unmount the storage.

umount <mount point>

From the above example:

umount /mnt/mmcblk0p1

Note: not unmount! We’ve made this mistake more than once!

Now that the card is no longer being used by the Omega, we can physically remove it without risking corruption.

The MicroSD card can now be safely removed.

Push it in firmly until you hear a click

Just push until it clicks.

MicroSD properly locked in slot

Now you can pull it out of the slot - careful not to lose it!

Pull the MicroSD out