The processor core of Keyestudio MEGA R3 development board is the ATMEGA2560-16AU , fully compatible with ARDUINO MEGA R3. 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, 1 ICSP header, and a reset button.