The high-performance, low-power Atmel 8-bit AVR RISC-based microcontroller combines 2KB ISP flash memory, 128B ISP EEPROM, 128B internal SRAM, universal serial interface (USI), full duplex UART, and debugWIRE for on-chip debugging. The device supports a throughput of 20 MIPS at 20 MHz and operates between 2.7-5.5 volts.By executing powerful instructions in a single clock cycle, the device achieves throughputs approaching 1 MIPS per MHz, balancing power consumption and processing speed.

Datasheet:

        http://www.atmel.com/Images/doc2543.pdf