用C语言实现串口通讯程序

1. 首先安装虚拟串口vspd软件，用于创建虚拟串口进行互联调试

2.打开vspd软件，选择COM1和COM4，点击Add pair，把COM1和COM4互联

3.打开虚拟串口助手，设置串口号为COM1，波特率为19200，其他设置使用默认值，点击连接

4.用C语言编写串口调试代码，使用COM4

typedef struct {
 HANDLE hCom;
 uint32_t baudrate;
 uint32_t bytesize;
 char parity;
 uint32_t stopbit;
}rs232_device;  

int set_opt(HANDLE hFile, int nSpeed, int nBits, char nEvent, int nStop)
{
 DCB dcb;
 COMMTIMEOUTS timeouts;  

//set input buf and output buf
 SetupComm(hFile, 512, 512);  

//set read timeout
 timeouts.ReadIntervalTimeout = 1000;
 timeouts.ReadTotalTimeoutMultiplier = 500;
 timeouts.ReadTotalTimeoutConstant = 5000;
//set write timeout
 timeouts.WriteTotalTimeoutMultiplier = 0;
 timeouts.WriteTotalTimeoutConstant = 2000;
 SetCommTimeouts(hFile, &timeouts);  

//store current setting
    if (0 == GetCommState(hFile, &dcb)){
        return -1;
    }  

//set BaudRate
 switch(nSpeed){
  case 2400:
   dcb.BaudRate = CBR_2400;
   break;
  case 4800:
   dcb.BaudRate = CBR_4800;
   break;
  case 115200:
   dcb.BaudRate = CBR_115200;
   break;
  default:
   dcb.BaudRate = CBR_9600;
   break;
 }  

//set ByteSize
 switch(nBits){
  case 7:
   dcb.ByteSize = 7;
   break;
  case 8:
   dcb.ByteSize = 8;
   break;
  default:
   dcb.ByteSize = 8;
   break;
 }  

//set Parity
 switch(nEvent){
  case 'N':
   dcb.Parity = NOPARITY;
   break;
  case 'O':
   dcb.Parity = ODDPARITY;
   break;
  case 'E':
   dcb.Parity = EVENPARITY;
   break;
 }  

//set StopBit
 switch(nStop){
  case 1:
   dcb.StopBits = ONESTOPBIT;
   break;
  case 2:
   dcb.StopBits = TWOSTOPBITS;
   break;
 }  

 if(0 == SetCommState(hFile, &dcb)){
  return -1;
 }  

    return 0;
}  

 rs232_device rs232_dev;
 rs232_dev.baudrate = 119200;
 rs232_dev.bytesize = 8;
 rs232_dev.parity = 'N'; 
 rs232_dev.stopbit = 1;
 //打开串口4
 rs232_dev.hCom = CreateFile("COM4",GENERIC_READ |GENERIC_WRITE, 0,NULL,OPEN_EXISTING,0,NULL);
 if (rs232_dev.hCom !=INVALID_HANDLE_VALUE){
  printf("Open COM4 OK!\n");
 }else 
  printf("Open COM4 Fail!\n");
 //通讯设置
 if(-1 == set_opt(rs232_dev.hCom,
     rs232_dev.baudrate,
     rs232_dev.bytesize,
     rs232_dev.parity,
     rs232_dev.stopbit))
 {
  if(INVALID_HANDLE_VALUE != rs232_dev.hCom)
   CloseHandle(rs232_dev.hCom); 
 }  

 unsigned char readBuf[1024] = {0};
 char writeBuf[1024] = "Hello Ketty!";
 int count = 100;
 DWORD readsize = 0;
 DWORD writesize = 0;
 int i;
 while(1){
  if(INVALID_HANDLE_VALUE != rs232_dev.hCom){
   printf("Start Read!\n");
   //串口读操作
   ReadFile(rs232_dev.hCom, readBuf, count, &readsize, NULL);
   printf("Read Buf=");
   for(i=0;i<readsize;i++)
    printf("%x ", readBuf[i]);
   printf("\n");
  }  

  //串口写操作
  WriteFile(rs232_dev.hCom, writeBuf, count, &writesize, NULL);
 }