用户手册（教学板子）XMEGA-A1U-Xplained-Pro

　　The Atmel® XMEGA® A1U Xplained Pro evaluation kit is a hardware platform to evaluate the ATxmega128A1U microcontroller. Supported by the Atmel Studio integrated development platform， the kit provides easy access to the features of the Atmel ATxmega128A1U and explains how to integrate the device in a custom design. The Xplained Pro MCU series evaluation kits include an on-board Embedded Debugger， and no external tools are necessary to program or debug the ATxmega128A1U. The Xplained Pro extension kits offers additional peripherals to extend the features of the board and ease the development of custom designs.

　　1. Introduction 1.1. Features • Atmel ATxmega128A1U microcontroller • Embedded debugger （EDBG） – USB interface – Programming and debugging on board XMEGA® through PDI – Virtual COM-port interface to target via UART – Atmel Data Gateway Interface （DGI） to target via USART and TWI – Four GPIOs connected to target for code instrumentation • Digital I/O – Two mechanical buttons （user and reset button） – One user LED – Three extension headers – Xplained Pro LCD extension connector • Three possible power sources – External power – Embedded debugger USB – Target USB • 32kHz crystal • External 512KB SRAM • USB interface， device mode