The Sensor Network Museumtm - Processor Systems: Atmel AVR 8 Bit

A generic family of easy to use, versatile and widely available 8 bit microcontrollers with excellent support through open source tools and development resources.

The Atmel AVR was selected for some of the first mote platforms and is still widely used today.

ATmega128 Data Sheet [pdf] [Rev.2467L-AVR-05/04]