SCM system can be completed within a file MicroSD card. Support Micro SD Card and Micro SDHC card (high speed card). Maximum storage of Micro SD card is 2GB, Micro SDHC card is 32GB. Document link: https(:)//www(dot)instructables(dot)com/id/Micro-SD-Card-Tutorial/ This is a Micro SD card reader module, reading and writing through the file system and the SPI interface driver. Please make sure the card format is FAT32 Microcontroller system to complete the MicroSD card read and write files. Ar-duino users can directly use the Ar-duino IDE comes with an SD card to complete the library card initialization and read and write. The signal in the direction of the Micro SD card is converted into 3.3V, and the MISO signal in the direction of the control interface from the MicroSD card is also converted into 3.3V. Generally, the AVR microcontroller system can read this signal.