The Arduino Mega 2560 is a microcontroller board based on the ATmega2560. It has 54 digital input/output pins (of which 15 can be used as PWM outputs), 16 analog inputs, 4 UARTs (hardware serial ports), a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Mega 2560 board is compatible with most shields designed for the Uno and the former boards Duemilanove or Diecimila.
The RC522 is a 13.56MHz RFID module that is based on the MFRC522 controller from NXP semiconductors. The module can supports I2C, SPI and UART and normally is shipped with a RFID card and key fob. It is commonly used in attendance systems and other person/object identification applications.
CNC Shield V3.0 can be used as drive expansion board for engraving machine, 3D printer and other devices. There’re 4 slots in the board for stepper motor drive modules, can drive 4 stepper motors, and each step stepper motor only need two IO port, that is to say, 6 IO ports can quite well to manage three stepper motor, it’s very convenient to use. After insert Arduino CNC Shield V3.0 into Arduino UNO, and installed GRBL firmware then you can quickly DIY a CNC engraving machine.