Microchip ATMEGA16U2-MU, 8bit AVR Microcontroller, ATmega, 16MHz, 16 kB Flash, 32-Pin QFN

The high-performance, low-power Microchip 8-bit AVR RISC-based microcontroller combines 16KB ISP flash memory with read-while-write capabilities, 512B EEPROM, 512-Byte SRAM, 22 general purpose I/O lines, 32 general purpose working registers, two flexible timer/counters with compare modes and PWM, USART, programmable watchdog timer with internal oscillator, SPI serial port, debugWIRE interface for on-chip debugging and programming, and five software selectable power saving modes.

High Performance, Low Power AVR® 8-Bit Microcontroller
Advanced RISC Architecture
Non-volatile Program and Data Memories
In-System Programming by on-chip Boot Program hardware-activated after reset
True Read-While-Write Operation
USB 2.0 Full-speed Device Module with Interrupt on Transfer Completion Operation
Bulk, Interrupt and Isochronous Transfers