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.
Arduino Pro Mini is minimal design approach to Arduino. This is a 3.3V and 5V Arduino running the 8MHz bootloader. Arduino Pro Mini does not come with connectors populated so that you can solder in any connector or wire with any orientation you need. We recommend first time Arduino users start with the Uno R3. It’s a great board that will get you up and running quickly. The Arduino Pro series is meant for users that understand the limitations of system voltage (3.3V) and (5V), lack of connectors, and USB off board.
The CNC Shield v4 is made for the control of 3D printers, milling and engraving machines. This version of the shield has 1 motor driver less than its predecessor, but is more compact and has room for an Arduino Nano. This board has 3 sockets for the installation of stepper motor drivers such as the A4988. Only 2 channels per motor are required to control this motor. There is also a connection for 2 end-stop switches per motor.
Module is used where short distance wireless communication is needed. The module is used for wireless communications of less than 100 meters. The module is preferred where power consumption is issue. HM-10 MODULE is designed by BLE chip so it consumes very less power to function. So the module can be used on mobile systems. The module uses UART communication and so it can be interfaced with almost all controllers or processors.