What is the Lock on a MicroSD Adapter Card? Hardware 20 AUG 2013

lock switch on a microSD adaptor casingBecause it is not painfully obvious as to what that little lock slide switch on the top left of a MicroSD adapter card is, I thought it worthwhile to drop a quick note for those of you who might be wondering just why your newly purchased MicroSD card appears to be read-only.

Despite the fact that you are slipping in a teensy weensy little MicroSD card into the gaping hole at the bottom of a much bigger SD adapter card (basically turning your MicroSD into a standard-sized SD card), the lock switch is in fact not there to give you ease of mind by ‘locking’ the smaller MicroSD card in place in the adapter card. (To be fair, the little micro card sits pretty snug in there anyway.)

Instead, the lock switch is used to toggle the read-only state of the MicroSD card, meaning that if the lock is slid down into the ‘locked’ position, no device into which the adapter card is now plugged can write back to the MicroSD card, thereby protecting your MicroSD card from having any data changed or removed. (It also helps against viruses inadvertently being added to the card.)

In other words, if you card appears to be ‘read only’, simply slide the lock switch back up into the ‘unlocked’ position and you should be able to happily write to your little piece of data storage.

And now you know.

(In case you’re wondering what the lock switch physically does, it simply bridges two contacts together, which then instructs the SD port that the device is in a read-only state).

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About Craig Lotter

South African software architect and developer at Touchwork. Husband to a cupcake baker and father to two little girls. I don't have time for myself any more.