Arduino Leonardo

A microcontroller board based around the ATmega 32u4 chip. Clocked at 16 MHz, it includes 32 KB of program flash (4 KB used by the bootloader), 2.5 KB of SRAM, and 1 KB of EEPROM.

Its footprint and pinout are mostly the same as the Uno. However, it features two independent UART serial streams (one USB and one on pins 0/1) and four user interrupt pins (0, 1, 2, 3, 7). The PWM pins are also shifted around slightly.