The Arduino Compatible Uno Rev3 is a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. Microcontroller ATmega328 Operating voltage 5V Input voltage (recommended) 7-12V Input voltage (limits) 6-20V Digital I/O pins 14 (of which 6 provide PWM output) Analog input pins 6 DC current per I/O Pin 40 mA DC current for 3.3V Pin 50 mA Flash memory 32 KB of which 0.5 KB used by bootloader SRAM 2 KB EEPROM 1 KB Clock speed 16 MHz.