用VC++6.0实现PC机与单片机之间的数据交换

　　1 Windows API通信函数方法

　　与通信有关的Windows API函数共有26个，但主要有关的有：

　　CreateFile() 用 “comn”（n为串口号）作为文件名就可以打开串口。

　　ReadFile() 读串口。

　　WriteFile() 写串口。

　　CloseHandle() 关闭串口句柄。

　　初始化时应注意CreateFile()函数中串口共享方式应设为0，串口为不可共享设备，其它与一般文件读写类似。以下给出API实现的源代码。

　　1.1 发送的例程

　　//声明全局变量

　　HANDLE m_hIDComDev；

　　OVERLAPPED m_OverlappedRead, m_Over lappedWrite;

　　//初始化串口

　　void CSerialAPIView::OnInitialUpdate()

　　{

　　CView::OnInitialUpdate();

　　Char szComParams[50];

　　DCB dcb;

　　Memset(m_OverlappedRead, 0, sizeof (OVERLAPPED));

　　Memset(m_OverlappedWrite, 0, sizeof (OVERLAPPED));

　　m_hIDComDev = NULL;

　　m_hIDComDev = CreateFile(“COM2”, GENERIC_READ│GENERIC_WRITE, 0, NULL,

　　OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL│FILE_FLAG_OVERLAPPED, NULL);

　　if (m_hIDComDev == NULL)

　　{

　　AfxMessageBox(“Can not open serial port!”);

　　goto endd;

　　}

　　memset(m_OverlappedRead, 0, sizeof (OVERLAPPED));

　　memset(m_OverlappedWrite, 0, sizeof (OVERLAPPED));

　　COMMTIMEOUTS CommTimeOuts;

　　CommTimeOuts.ReadIntervalTimeout=0×FFFFFFFF;

　　CommTimeOuts.ReadTotalTimeoutMultiplier = 0;

　　CommTimeOuts.ReadTotalTimeoutConstant = 0;

　　CommTimeOuts.WriteTotalTimeoutMultiplier = 0;

　　CommTimeOuts.WriteTotalTimeoutConstant = 5000;

　　SetCommTimeouts(m_hIDComDev, CommTimeOuts);

　　Wsprintf(szComparams, “COM2:9600, n, 8, 1”);

　　m_OverlappedRead. hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

　　m_OverlappedWrite. hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

　　dcb. DCBlength = sizeof(DCB);

　　GetCommState(m_hIDComDev, dcb);

　　dcb. BaudRate = 9600;

　　dcb. ByteSize= 8;

　　unsigned char ucSet;

　　ucSet = (unsigned char) ((FC_RTSCTSFC_DTRDSR) != 0);

　　ucSet = (unsigned char) ((FC_RTSCTSFC_RTSCTS) ! = 0);

　　ucSet = (unsigned char) ((FC_RTSCTSFC_XONXOFF) ! = 0);

　　if (!SetCommState(m_hIDComDev, dcb)‖

　　!SetupComm(m_hIDComDev,10000,10000)‖

　　m_OverlappedRead. hEvent ==NULL‖

　　m_OverlappedWrite. hEvent ==NULL)

　　{

　　DWORD dwError = GetLastError();

　　if (m_OverlappedRead. hEvent != NULL)

　　CloseHandle(m_OverlappedRead. hEvent);

　　if (m_OverlappedWrite. hEvent != NULL)

　　CloseHandle(m_OverlappedWrite. hEvent);

　　CloseHandle(m_hIDComDev);

　　}

　　endd:

　　;

　　}

　　//发送数据

　　void CSerialAPIView::OnSend()

　　{

　　char szMessage[20] = “thank you very much”;

　　DWORD dwBytesWritten;

　　for (int i=0; isizeof(szMessage); i++)

　　{

　　WriteFile(m_hIDComDev, (LPSTR)szMessage[i], 1, dwBytesWritten, m_OverlappedWrite);

　　if (WaitForSingleObject(m_OverlapperWrite, hEvent, 1000))dwBytesWritten = 0;

　　else

　　{

　　GentOverlappedResult(m_hIDComDev, m_OverlappedWrite, dwBytesWritten, FALSE);

　　m_OverlappedWrite. Offset += dwBytesWritten;

　　}