This document contains complete and detailed description of all modules included in the Atmel®AVR®XMEGA®AU microcontroller family. The Atmel AVR XMEGA AU is a family of low-power, high-performance, and peripheral-rich CMOS 8/16-bit microcontrollers based on the AVR enhanced RISC architecture. The available Atmel AVR XMEGA AU modules described in this manual are:  Atmel AVR CPU  Memories  DMAC - Direct memory access controller  Event system  System clock and clock options  Power management and sleep modes  System control and reset  Battery backup system  WDT - Watchdog timer  Interrupts and programmable multilevel interrupt controller  PORT - I/O ports  TC - 16-bit timer/counters  AWeX - Advanced waveform extension  Hi-Res - High resolution extension  RTC - Real-time counter  RTC32 - 32-bit real-time counter  USB - Universal serial bus interface  TWI - Two-wire serial interface  SPI - Serial peripheral interface  USART - Universal synchronous and asynchronous serial receiver and transmitter  IRCOM - Infrared communication module  AES and DES cryptographic engine  CRC - Cyclic redundancy check  EBI - External bus interface  ADC - Analog-to-digital converter  DAC - Digital-to-analog converter  AC - Analog comparator  IEEE 1149.1 JTAG interface  PDI - Program and debug interface  Memory programming  Peripheral address map  Register summary  Interrupt vector summary  Instruction set summary