SHDC协议，SD2.0。单片机开发，大容量的SD卡开发协议，2G以下与2G以上的SD,microSD卡协议不一样。一个可以用SPI，另一个可以用SD协议-The SHDC agreement, SD 2.0. MCU development, large-capacity SD card development agreement, 2G following agreement with more than 2G SD and microSD card is not the same. One