S3C2416 看门狗

原理：看门狗自己有个硬件计数器，看门狗开启后，计数器就开始计数，当计数为0时触发，触发事件有两个：系统复位和中断，可设置屏蔽。

　　在计数器计数到0之前，程序可以重新设置计数器中的数值，称之喟狗。计数器的值设置完后，计数器重新用新的数值开始计数。

　　看门狗开启后，由于应用程序挂了或系统当机了就会使得喟狗操作不再执行，计数器计数到0时就产生中断或复位。

喟狗时间＝(((预分频设置值+1)*分频系数)/PCLK) *计数器值

主要设置2个寄存器：WTCON和WTCNT。另外WTDAT里面的值是给看门狗开启后第一次自动赋值给WTCNT的，之后不再从WTDAT赋值给WTCNT，必须手动更新WTCNT的值，此操作为喟狗。

关键驱动代码：

#define　　IOCTL_WDG_OPEN　　　　 0x20    //    打开看门狗
#define　　IOCTL_WDG_CLOSE　　　　0x21    //    关闭看门狗
#define　　IOCTL_WDG_FEED　　　　 0x22    //    喟狗

BOOL
WDG_IOControl(
              DWORD Handle,
              DWORD dwIoControlCode,
              PBYTE pInBuf,
              DWORD nInBufSize,
              PBYTE pOutBuf,
              DWORD nOutBufSize,
              PDWORD pBytesReturned
              )
{
    switch(dwIoControlCode)
    {
        case IOCTL_WDG_OPEN:    //    打开设置看门狗
            v_pWDGregs->WTCON = 0xFF39;   //设置看门狗控制寄存器
            v_pWDGregs->WTCNT = 0x3FC6;　　
            RETAILMSG(, (TEXT("WDG: Open WatchDog\r\n")));
            break;

        case IOCTL_WDG_CLOSE:    //    关闭看门狗
            v_pWDGregs->WTCON = 0x0000;
            RETAILMSG(, (TEXT("WDG: Close WatchDog\r\n")));
            break;

        case IOCTL_WDG_FEED:    //    喟狗
            v_pWDGregs->WTCNT = 0x3FC6;　　//Time=(((Prescaler+1)*Division)/PCLK) *WTCNT=(((255+1)*128)/(400M/6)) *16326=8.02455552秒
            break;

        default:
            break;
    }

    return TRUE;
}   // WDG_IOControl

附件下载

C++应用程序：

#define     IOCTL_WDG_OPEN            0x20    //    打开看门狗
#define     IOCTL_WDG_CLOSE        　　0x21    //    关闭看门狗
#define     IOCTL_WDG_FEED            0x22    //    喟狗

HANDLE wdgdriver;

void WDGInit()
{
    wdgdriver= CreateFile(L,NULL,OPEN_EXISTING,,NULL);
}

void Openwdg()
{
    //开启看门狗
    DeviceIoControl(wdgdriver,IOCTL_WDG_OPEN,NULL,,NULL,,NULL,NULL);
}

void Feedwdg()
{
    //喂狗
    DeviceIoControl(wdgdriver,IOCTL_WDG_FEED,NULL,,NULL,,NULL,NULL);
}

void Closewdg()
{
    //关闭看门狗
    DeviceIoControl(wdgdriver,IOCTL_WDG_CLOSE,NULL,,NULL,,NULL,NULL);
}

C#应用程序：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

using System.Runtime.InteropServices;
using System.Threading;

namespace WatchDog
{
    public partial class WDG : Form
    {
        //几个驱动操作参数
        ;
        const UInt32 GENERIC_READ = 0x80000000;
        const UInt32 GENERIC_WRITE = 0x40000000;
        ;

        private IntPtr hPort;

        //导入设备管理器API
        [DllImport("coredll.dll")]
        public static extern IntPtr CreateFile(String lpFileName, UInt32 dwDesiredAccess, UInt32 dwShareMode, IntPtr lpSecurityAttributes, UInt32 dwCreationDisposition, UInt32 dwFlagsAndAttributes, IntPtr hTemplateFile);
        [DllImport("coredll.dll")]
        public static extern bool DeviceIoControl(IntPtr hDevice, UInt32 dwIoControlCode, UInt32 lpInBuffer, UInt32 nInBufferSize, Byte[] lpOutBuffer, UInt32 nOutBufferSize, UInt32 lpBytesReturned, IntPtr lpOverlapped);

        public WDG()
        {
            InitializeComponent();

            //打开看门狗驱动
            hPort = CreateFile(, IntPtr.Zero, OPEN_EXISTING, , IntPtr.Zero);

            if (hPort == (IntPtr)INVALID_HANDLE_VALUE)
            {
                MessageBox.Show("Open Driver WDG1: Failed");
                return;
            }
        }

        private void OpenWDG_Click(object sender, EventArgs e)
        {
            DeviceIoControl(hPort, , , , , IntPtr.Zero);//开始看门狗
        }

        private void CloseWDG_Click(object sender, EventArgs e)
        {
            DeviceIoControl(hPort, , , , , IntPtr.Zero);//关闭看门狗
        }

        private void FeedWDG_Click(object sender, EventArgs e)
        {
            DeviceIoControl(hPort, , , , , IntPtr.Zero);//喟狗
        }

    }
}