按键检测电路原理图（点击图片放大，不需要放大镜！）

/*This file has been prepared for Doxygen automatic documentation generation.*/
/*! \file *********************************************************************
*
* \brief GPIO example application for AVR32 UC3.
*
* - Compiler: IAR EWAVR32 and GNU GCC for AVR32
* - Supported devices: All AVR32 devices with GPIO.
* - AppNote:
*
* \author Atmel Corporation: http://www.atmel.com \n
* Support and FAQ: http://support.atmel.no/
*
*****************************************************************************/

/*! \page License
* Copyright (c) 2007, Atmel Corporation All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* 3. The name of ATMEL may not be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY ATMEL ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY AND
* SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/*! \mainpage
* \section intro Introduction
* This is the documentation for the data structures, functions, variables,
* defines, enums, and typedefs for the GPIO driver.
*
* The General Purpose Input/Output manages the I/O pins of the microcontroller. Each I/O line
* may be dedicated as a general-purpose I/O or be assigned to a function of an embedded peripheral.
* This assures effective optimization of the pins of a product.
*
* The given example covers various use of the GPIO controller and demonstrates
* different GPIO functionality. It uses a LED and the push button PB0.
*
* \section files Main Files
* - gpio.c: GPIO driver;
* - gpio.h: GPIO driver header file;
* - gpio_example.c: GPIO example application.
*
* \section compinfo Compilation Info
* This software was written for the GNU GCC for AVR32 and IAR Systems compiler
* for AVR32. Other compilers may or may not work.
*
* \section deviceinfo Device Info
* All AVR32 devices with a GPIO module can be used. This example has been tested
* with the following setup:<BR>
* <ul>
* <li>EVK1100 or EVK1101 evaluation kit.
* </ul>
*
* \section setupinfo Setup Information
* <BR>CPU speed: <i> Internal RC oscillator (about 115200 Hz). </i>
*
* \section contactinfo Contact Information
* For further information, visit
* <A href="http://www.atmel.com/products/AVR32/">Atmel AVR32</A>.\n
* Support and FAQ: http://support.atmel.no/
*/

#include "compiler.h"
#include "gpio.h"
#include "board.h"

#define GPIO_PIN_EXAMPLE_1 LED2_GPIO
#define GPIO_PIN_EXAMPLE_2 LED3_GPIO
#define GPIO_PIN_EXAMPLE_3 GPIO_PUSH_BUTTON_0

/*! \brief This is an example of how to access the gpio.c driver to set, clear, toggle... the pin GPIO_PIN_EXAMPLE.
*/
int main(void)
{
U32 state = 0;
U32 i;

gpio_enable_pin_glitch_filter(GPIO_PIN_EXAMPLE_3);
while (1)
{
switch (state)
{
case 0:
// Access with GPIO driver gpio.c with clear and set access.
gpio_clr_gpio_pin(GPIO_PIN_EXAMPLE_1);
state++;
break;

case 1:
gpio_set_gpio_pin(GPIO_PIN_EXAMPLE_1);
state++;
break;

case 2:
// Note that it is also possible to use the GPIO toggle feature.
gpio_tgl_gpio_pin(GPIO_PIN_EXAMPLE_1);
state++;
break;

case 3:
default:
gpio_tgl_gpio_pin(GPIO_PIN_EXAMPLE_1);
state = 0;
break;
}

// Poll push button value.
for (i = 0; i < 1000; i += 4)
{
if (gpio_get_pin_value(GPIO_PIN_EXAMPLE_3) == 0)
gpio_clr_gpio_pin(GPIO_PIN_EXAMPLE_2);
else
gpio_set_gpio_pin(GPIO_PIN_EXAMPLE_2);
}
}
}

　　 按按键键，LED将显示相应的状态。