The Arduino Mega 2560 is a microcontroller board based on the ATmega 2560 . It has 54 digital input/output pins (of which 14 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. Applications  Multi-sensor robotics (many sensors + motor drivers) 3D printers, CNC controllers & motion control projects Home automation hubs and advanced IoT gateways Complex data-logging systems with many analog channels Educational kits and advanced electronics labs Prototyping products that require many serial peripherals (GPS, GSM, LoRa, Bluetooth, multiple sensors)

Uno R3 is the clone one of the latest version of Arduino Uno with an on-board CH340 usb – serial converter chip. Even there are some little differences respect to original one, it is almost the same in terms of usage and software. This provides you a cheaper opportunitiy to get started with Arduino boards. The microcontroller model of this board is the same as the original one (Atmega328). The only difference between microcontrollers is ther package. Original one has a DIP package but the clone one has SMD package microcontroller. Despite being a clone one, there are a pin group (4x GND, 2x 5 V, 2x 3.3 V, 1x RX/TX, 1x SCL/SDA) near to the crystal oscillator and there are external pin holes allow you to solder male headers on the board too.