Specifications:

1- Support Micro SD Card, Micro SDHC card (high-speed card)
2- The level conversion circuit board that can interface level is 5V or 3.3V
3- Communication interface is a standard SPI interface
4- Control Interface: A total of six pins (GND, VCC, MISO, MOSI, SCK, CS), GND to ground
5- VCC is the power supply, MISO, MOSI, SCK is the SPI bus, CS is the chip select signal pin
6- 3.3V regulator circuit: LDO regulator output 3.3V as level converter chip, Micro SD card supply
7- Level conversion circuit: Micro SD card into the direction of signals into 3.3V, MicroSD card toward the direction of the control interface MISO signal is also converted to 3.3V, general AVR microcontroller system can read the signal.