用VC++6.0實現PC機與單片機之間的數據交換

　　1 Windows API通信函數方法

　　與通信有關的Windows API函數共有26個，但主要有關的有：

　　CreateFile() 用 “comn”（n為串口號）作為文件名就可以打開串口。

　　ReadFile() 讀串口。

　　WriteFile() 寫串口。

　　CloseHandle() 關閉串口句柄。

　　初始化時應注意CreateFile()函數中串口共享方式應設為0，串口為不可共享設備，其它與一般文件讀寫類似。以下給出API實現的源代碼。

　　1.1 發送的例程

　　//聲明全局變量

　　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:

　　;

　　}

　　//發送數據

　　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;

　　}