The microcontroller systems may have to back up the data which they have read during their operation or the data which they need to access during their running time. Most of the microcontrollers have built-in EEPROM memory but they come in comparatively small sizes. In order to use the microcontroller in applications like file accessing, media player etc. an external memory card is necessary.
The SD memory card comes in large storage capacities ranging from 1 GB to 8 GB and they are compatible with the SPI bus of the microcontroller. The large storage capacity and simplicity in interfacing results in wide usage of SD memory card by the microcontrollers. The files in an SD memory card are stored using FAT32 or FAT16 and one should use the code or FAT file-system library to access the files from an SD card.
The easy prototyping platform Arduino provides a library for accessing the SD memory cards. This particular project explains how to interface a SD card using an Arduino board
and perform some read and write operations on it.