This carrier board makes it easy to interface a microSD memory card (originally known as TransFlash) with an SPI-capable microcontroller, offering a convenient and inexpensive way to add gigabytes of non-volatile storage to an embedded project. It includes a 3.3 V regulator and level shifters on the four SPI lines, enabling direct integration into 5 V systems, and it provides access to the all of the connections through single 1×9 row of 0.1?-spaced through-holes. A breakaway 0.1? male header strip is included, which can be soldered in to use the board with breadboards, perfboards, or 0.1? female connectors, and the board has two mounting holes for #2 or M2 screws.
Since many microcontrollers have built-in SPI interfaces, most hobbyist projects communicate with Secure Digital cards in SPI bus mode; this is the only mode supported by this board. (The alternative SD bus mode is proprietary, and a license from the SD Association is required for access to the full specifications.) The pins on this board are labeled according to their functions in SPI mode.