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Accessing the MultiMediaCard (MMC)

You can write your application(s) to store data on an MMC card using the BlackDog memory card slot. The MMC card slot on the BlackDog device reads data at a maximum speed of 12Mb/s and writes at a maximum speed of 10.4Mb/s, depending on the card.

Accessing the MMC card requires three drivers to be present:

• mmc block. Exposes the mmc interface to be used as a block device.
• mmc. Supports the mmc protocol.
• realm_mmc. Is the realm "mmc host" driver.

By default, these drivers should already be compiled into your BlackDog kernel. When an MMC card is inserted into the memory card slot, the realm_mmc driver detects the card's presence and posts the message "MMC Slot; Card Detected" into /var/log/messages. The MMC card should then show up as the device /dev/mmc1. At this point, the MMC card should be mounted, so it can be accessed as a file system.

Mounting the MMC Card

1. Make sure the MMC card is fully inserted into the MMC card slot (you should hear a 'click').
2. Mount the MMC device by typing: mount -t vfat /dev/mmc1 /mnt/mmc1. Unless an error is returned, the MMC is now mounted.
3. You can confirm the MMC is mounted by typing: df. This will return a list of all mounted file systems.
4. You can now use the MMC as you would any other drive.

Unmounting the MMC Card

Note: You must unmount the MMC card before removing it, or data may be lost.

Before removing the MMC card, you must first unmount it by typing: umount /mnt/mmc1. Otherwise, certain edits and changes to storage may not be written to the MMC card and may be lost. Unmounting the card before removing it forces data to be synchronized between the BlackDog device and the MMC card.

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