串口收到的为什么是乱码

OpenQNX中文论坛 四海同心QNX论坛
1

用下面的代码收串口的数据，收到的字节数对，可是数据不对是乱码。会是什么问题呢？代码如下：
int SetupCOM(int com, long baud, int parity, int databit,int stopbit)
{
int fd;
char path[20];
U32 comflag=0;
struct termios termios_p;
switch ( com )
{
case COM1:
strcpy(path,"/dev/ser1");
break;
case COM2:
strcpy(path,"/dev/ser2");
break;
default:
break;
}

if ( ( fd = open ( path, O_RDWR,S_IRUSR | S_IWUSR) ) != -1 )
{
//设置波特率
tcgetattr( fd, &termios_p );
cfsetispeed( &termios_p, baud );
cfsetospeed( &termios_p, baud );
tcsetattr( fd, TCSADRAIN, &termios_p );

switch(databit)
{
case DATABIT_5:
comflag |= CS5 | CREAD;
break;
case DATABIT_6:
comflag |= CS6 | CREAD;
break;
case DATABIT_7:
comflag |= CS7 | CREAD;
break;
case DATABIT_8:
comflag |= CS8 | CREAD ;
break;
}
switch(stopbit)
{
case STOPBIT_1:
comflag &= ~CSTOPB;
break;
case STOPBIT_2:
comflag |= CSTOPB;
break;
}
switch(parity)
{
case NO_PARITY:
comflag &= ~PARENB;
break;
case EVEN_PARITY:
comflag |= PARENB;
comflag &=~ PARODD;
break;
case ODD_PARITY:
comflag |= PARENB;
comflag |= PARODD;
break;
}
tcgetattr( fd, &termios_p );
termios_p.c_cflag = comflag;
tcsetattr( fd, TCSADRAIN, &termios_p );

}
return fd;
}
int fd=SetupCOM(COM2, 9600, EVEN_PARITY, DATABIT_8,STOPBIT_1);
if((ReceivedSize=readcond(fd,TempReceivedData,30,512,1,2))<0)

2

实在不行可以试试下面的代码：）
串口波特率设置
static void serial_port_speed_set(int speed,struct termios options)
{
/

  • set the baud rates to speed
    /
    cfsetispeed(options,speed);
    cfsetospeed(options,speed);
    /
  • enable the receiver and set local mode
    */
    options->c_cflag |= (CLOCAL | CREAD);
    }
    串口数据位设置
    static void serial_port_character_size_set(int data_size,struct termios options)
    {
    /
  • mask the character size bits
    */
    options->c_cflag &= ~CSIZE;
    switch(data_size)
    {
    case 5:
    options->c_cflag |= CS5;
    break;
    case 6:
    options->c_cflag |= CS6;
    break;
    case 7:
    options->c_cflag |= CS7;
    break;
    case 8:
    options->c_cflag |= CS8;
    break;
    default:
    printf(“error data size config!\n”);
    exit(EXIT_FAILURE);
    }
    }
    串口校验位设置
    static void serial_port_parity_set(char parity_mode,struct termios *options)
    {
    switch(parity_mode)
    {
    case ‘n’:
    case ‘N’:
    options->c_cflag &= ~PARENB;//clear parity enable
    options->c_iflag &= ~INPCK;//disable parity checking
    break;
    case ‘o’:
    case ‘O’:
    options->c_cflag |= (PARODD | PARENB);//奇校验
    options->c_iflag |= INPCK;//disable parity checking
    break;
    case ‘e’:
    case ‘E’:
    options->c_cflag |= PARENB;//enable parity
    options->c_cflag &= ~PARODD;//偶校验
    options->c_iflag |= INPCK;//disable parity checking
    break;
    case ‘s’:
    case ‘S’:
    options->c_cflag &= ~PARENB;
    options->c_cflag &= ~CSTOPB;
    break;
    default:
    printf(“unsupported parity\n”);
    exit(EXIT_FAILURE);
    }
    }
    串口停止位设置
    static void serial_port_stop_set(int stopbits,struct termios options)
    {
    switch(stopbits)
    {
    case 1:
    options->c_cflag &= ~CSTOPB;
    break;
    case 2:
    options->c_cflag |= CSTOPB;
    break;
    default:
    printf(“unsupported stop bits\n”);
    exit(EXIT_FAILURE);
    }
    }
    对上面几个设置函数的封装
    void serial_port_config(int fd,int speed,int data_size,
    char parity_mode,int stopbits)
    {
    struct termios options;
    /
  • get the current options for the port
    /
    tcgetattr(fd,&options);
    /
  • do what you want
    /
    serial_port_speed_set(speed,&options);
    serial_port_character_size_set(data_size,&options);
    serial_port_parity_set(parity_mode,&options);
    serial_port_stop_set(stopbits,&options);
    /
  • disable hardware flow control
    /
    options.c_cflag &= ~(IHFLOW | OHFLOW);
    /    *
  • choose raw input
    /
    options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
    /    *
  • choose raw output
    /
    options.c_oflag &= ~OPOST;
    /    *
  • minimum number of characters to read
    /
    options.c_cc[VMIN] = 0;
    /    *
  • time to wait for data
    /
    options.c_cc[VTIME] = 5;
    /
  • set new options for the port
    */
    tcsetattr(fd,TCSANOW,&options);
    }
    我把qnx当成unix来编程，这个也就是按照posix协议写的。具体原理的话可以看看unix高级编程那本书：）
3

你这程序试过OK吗？

4

试过，x86的机器上。

5

找到原因了，波特率应该加B