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    记得以前学习单片机，首先是流水灯然后是按键、中断、定时器…… 最近几年键盘手机也是渐渐的被触摸屏幕的手机所取代。SIN210开发板上有一块FT液晶屏，并配有一个电阻触摸屏，所以一直没鼓捣按键，今天参考了下SINLINX公司提供的教程，来鼓捣一下按键。。。

    SIN210开发板上具有8个按键，电路图如下：

                               图9-1：User Key

EINT0~7 就是对应的和CPU的GPH0_0 ~ GH0_7  如下图所示：

                              图9-1-1：User Key

开发板上的按键，是借助linux的input子系统进行的修改。

一、驱动

（1）编辑/kernel/drivers/input/keyboard/s3c-gpio_keys.c 文件
（2）修改 s3c_gpio_keys 结构体

struct s3c_gpio_key s3c_gpio_keys[]=
{
{
.pin = S5PV210_GPH0(0),
.eintcfg = 0X0f<<0,
.inputcfg = 0<<0,
.eint = IRQ_EINT0,
},

/*剩下的7个，与这个类似，在这里就不重复了*/ };

} 

static struct gpio_keys_button gpio_buttons[] = {
{
.gpio
= S5PV210_GPH0(0),
.code
= 231,
.desc
= "CALL",
.active_low = 1,
.wakeup
= 1,
},

二、应用（主要就是写个简单的程序来通过Qt来显示哪个键被按下）

（1）新建一个Qt工程

（2）新建key.c key.h  led.c文件如下

//key.c
#include "key.h"
#include 
#include 
#include 
#include 
#include 
#define NOKEY 0

int key_fd=0;
struct input_event t;

int key_open(const char*devname)
{
  key_fd=open(devname,O_RDWR);
  printf("KEY driver is ok\n");
  if(key_fd<0)
  {
     printf("open device %s failed.\n",devname);
     return -1;
  }
  return 0;
}

int key_read()
{
   if(read(key_fd,&t,sizeof(t))==sizeof(t))
        {
		if(t.type==EV_KEY)
		if(t.value==0 || t.value==1)
		 {
		    switch(t.code)
		    {
            case 231:
                printf("S1 %s\n",(t.value)?"Pressed":"Released");
                return ((t.value)?0x11:0x10);
                break;
			case 139:
				printf("S2 %s\n",(t.value)?"Pressed":"Released");
                return ((t.value)?0x21:0x20);
				break;
			case 158:
				printf("S3 %s\n",(t.value)?"Pressed":"Released");
				return ((t.value)?0x31:0x30);
                break;			
			case 107:
				printf("S4 %s\n",(t.value)?"Pressed":"Released");
                return ((t.value)?0x41:0x40);
				break;
            case 102:
                printf("S5 %s\n",(t.value)?"Pressed":"Released");
                return ((t.value)?0x51:0x50);
                break;
			case 30:
				printf("S6 %s\n",(t.value)?"Pressed":"Released");
				return ((t.value)?0x61:0x60);
				break;
			case 48:
				printf("S7 %s\n",(t.value)?"Pressed":"Released");
				return ((t.value)?0x71:0x70);
				break;
			case 46:
				printf("S8 %s\n",(t.value)?"Pressed":"Released");
                return ((t.value)?0x81:0x80);
				break;
			default:
				break;
		    }
          }
	}

}


int key_close(void){
 if(key_fd)
  close(key_fd);
}
/************************************/
//led.c
#include "key.h"
#include 
#include 
#include 
#include 
#include 

#define IOCTL_LED_ON    0
#define IOCTL_LED_OFF   1

int led_fd=0;
int led_open(const char*devname){
 led_fd=open(devname,O_RDWR);
 printf("LED driver is ok\n");
 if(led_fd<0){
  printf("open device %s failed.\n",devname);
  return -1;
 }
 return 0;
}
int led_ioctl(const int no,const int sw){
 //led_fd=open("/dev/led",O_RDWR);
 int num=no;
 ioctl(led_fd,sw,num);
 printf("LED%dis open\n",num);
 return 0;
}
int led_close(void){
 if(led_fd)
  close(led_fd);
}


/*********************************/
//key.h
#ifndef KEY_H
#define KEY_H
#ifdef __cplusplus
extern "C" {
#endif

extern int key_open(const char *devname);
extern int key_read();
extern int key_close(void);
extern int key_fd;

extern int led_open(const char *devname);
extern int led_ioctl(const int no,const int sw);
extern int led_close(void);
extern int led_fd;

#ifdef __cplusplus
}
#endif
#endif 

用到了一个Qt的QSocketNotifier。

QSocketNotifier 用来监听系统文件操作，将操作转换为Qt事件进入系统的消息循环队列。并调用预先设置的事件接受函数，处理事件。一共存在3类事件：read,write,exception.

QSocketNotifier::Read     0     There is data to be read.

QSocketNotifier::Write     1     Data can be written.

QSocketNotifier::Exception     2     An exception has occurred. We recommend against using this.

通过QSocketNotifier来监听是否有按键按下的事件，通过槽和按键处理函数buttonOnclik（）连接。

代码如下：

/*mainwindow.h*/
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include#include 

namespace Ui {
class MainWindow;
//class QSocketNotifier;
}
class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
protected:
void paintEvent(QPaintEvent* e);


private slots:
    void buttonClicked();

private:
    int k_fd;
    int led_fd;
    QSocketNotifier* m_notifier;

private:
    Ui::MainWindow *ui;


};

#endif // MAINWINDOW_H


//mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include#include 
#include "key.h"

#define LED1    0
#define LED2    1
#define LED3    2
#define LED4    3

#define LED_ON  0
#define LED_OFF 1
//int led_fd;
int mm_key=0,last_key=0;
//int m_notifier;
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    k_fd=key_open("/dev/input/event0");
    if(led_fd==-1)
        QMessageBox::warning(this, tr("Error"), tr("Not Found /dev/led !"));

    led_fd=led_open("/dev/led");
    if(k_fd==-1)
        QMessageBox::warning(this, tr("Error"), tr("Not Found /dev/input/event0 !"));

    m_notifier = new QSocketNotifier(k_fd, QSocketNotifier::Read, this);

    connect (m_notifier, SIGNAL(activated(int)), this, SLOT(buttonClicked()));

}

void MainWindow::buttonClicked()
{
   mm_key=key_read();
   if(mm_key!=last_key)
   {
        last_key=mm_key;update();
   }
}
void MainWindow::paintEvent(QPaintEvent*)
{

   switch(last_key)
       {
         case 0x11: ui->KeyDis->setText("S1 is Pressed0!");   led_ioctl(LED1,LED_ON);    break;
         case 0x21: ui->KeyDis->setText("S2 is Pressed!");    led_ioctl(LED1,LED_OFF);   break;
         case 0x31: ui->KeyDis->setText("S3 is Pressed!");    led_ioctl(LED2,LED_ON);    break;
         case 0x41: ui->KeyDis->setText("S4 is Pressed!");    led_ioctl(LED2,LED_OFF);   break;
         case 0x51: ui->KeyDis->setText("S5 is Pressed!");    led_ioctl(LED3,LED_ON);    break;
         case 0x61: ui->KeyDis->setText("S6 is Pressed!");    led_ioctl(LED3,LED_OFF);   break;
         case 0x71: ui->KeyDis->setText("S7 is Pressed!");    led_ioctl(LED4,LED_ON);    break;
         case 0x81: ui->KeyDis->setText("S8 is Pressed!");    led_ioctl(LED4,LED_OFF);   break;

       }
}
MainWindow::~MainWindow()
{
    led_close();
    key_close();
    delete ui;
}

通过屏幕来显示那个按键被按下，具体显示如下：

              图9-2-1：Qt-key显示

              图9-2-2：Qt-key显示

              图9-2-3：Qt-key显示

              图9-2-4：Qt-key显示