求助关于Linux下串口收数据的问题

lishi_1991 2014-07-17 11:13:00

现在想做一个项目从windows通过串口向arm-linux发几字节的小数据，写完程序调试时候发现Linux下串口默认行缓冲，收到数据先放在缓冲区内，只有当收到回车符的才会发出SIGIO信号，这是才能read出数据。
但是项目中windows下发数据不是由我控制的，发送数据无法自动添加回车符，这样windows下发送小数据的时候，我这边Linux程序就read不出数据，这该怎么解决呢？
下面贴上我串口设置及收数据的代码：

串口设置代码：

int OpenDev(char *Dev)

{

    //int fd = open( Dev,  O_RDWR | O_NOCTTY | O_NDELAY );         //| O_NOCTTY | O_NDELAY    

    int fd = open( Dev,  O_RDWR);         //| O_NOCTTY | O_NDELAY    

    if (fd == -1)   

    {           

        perror("Can't Open Serial Port");

        return -1;      

    }   

    else    

		{

      return fd;

		}

}

/**

*@brief  设置串口通信速率

*@param  fd     类型 int  打开串口的文件句柄

*@param  speed  类型 int  串口速度

*@return  void

*/

int speed_arr[] = { B38400, B19200, B9600, B4800, B2400, B1200, B300,

                    B38400, B19200, B9600, B4800, B2400, B1200, B300, };

int name_arr[] = {38400,  19200,  9600,  4800,  2400,  1200,  300, 38400,  

                    19200,  9600, 4800, 2400, 1200,  300, };

void set_speed(int fd, int speed)

{

    int   i; 

    int   status; 

    struct termios   Opt;

    tcgetattr(fd, &Opt); 

    for ( i= 0;  i < sizeof(speed_arr) / sizeof(int);  i++) { 

        if  (speed == name_arr[i]) {     

            tcflush(fd, TCIOFLUSH);     

            cfsetispeed(&Opt, speed_arr[i]);  

            cfsetospeed(&Opt, speed_arr[i]);   

            status = tcsetattr(fd, TCSANOW, &Opt);  

            if  (status != 0) {        

                perror("tcsetattr fd1");  

                return;     

            }    

            tcflush(fd,TCIOFLUSH);   

        }  

    }

}

int set_Parity(int fd,int databits,int stopbits,int parity)

{ 

    struct termios options; 

    options.c_lflag  &= ~(ICANON | ECHO | ECHOE | ISIG);  /*Input*/

    options.c_oflag  &= ~OPOST;   /*Output*/

    if  ( tcgetattr( fd,&options)  !=  0) { 

        perror("SetupSerial 1");     

        return(FALSE);  

    }

    options.c_cflag &= ~CSIZE; 

    switch (databits)

    {   

    case 7:     

        options.c_cflag |= CS7; 

        break;

    case 8:     

        options.c_cflag |= CS8;

        break;   

    default:    

        fprintf(stderr,"Unsupported data size/n"); return (FALSE);  

    }

    switch (parity) 

    {   

        case 'n':

        case 'N':    

            options.c_cflag &= ~PARENB;   /* Clear parity enable */

            options.c_iflag &= ~INPCK;     /* Enable parity checking */ 

            break;  

        case 'o':   

        case 'O':     

            options.c_cflag |= (PARODD | PARENB); /* 设置为奇效验*/  

            options.c_iflag |= INPCK;             /* Disnable parity checking */ 

            break;  

        case 'e':  

        case 'E':   

            options.c_cflag |= PARENB;     /* Enable parity */    

            options.c_cflag &= ~PARODD;   /* 转换为偶效验*/     

            options.c_iflag |= INPCK;       /* Disnable parity checking */

            break;

        case 'S': 

        case 's':  /*as no parity*/   

            options.c_cflag &= ~PARENB;

            options.c_cflag &= ~CSTOPB;break;  

        default:   

            fprintf(stderr,"Unsupported parity/n");    

            return (FALSE);  

    }  

    /* 设置停止位*/  

    switch (stopbits)

    {   

        case 1:    

            options.c_cflag &= ~CSTOPB;  

            break;  

        case 2:    

            options.c_cflag |= CSTOPB;  

           break;

        default:    

             fprintf(stderr,"Unsupported stop bits/n");  

             return (FALSE); 

    } 

    /* Set input parity option */ 

    if (parity != 'n')   

        options.c_iflag |= INPCK; 

    //tcflush(fd,TCIFLUSH);

    tcflush(fd,TCIOFLUSH);

    options.c_cc[VTIME] = 150; /* 设置超时15 seconds*/   

    options.c_cc[VMIN] = 0; /* Update the options and do it NOW */

    if (tcsetattr(fd,TCSANOW,&options) != 0)   

    { 

        perror("SetupSerial 3");   

        return (FALSE);  

    } 

    return (TRUE);  

}

读取数据代码：

void *uart_recv(void *args)

{

	int fd_uart;

    int nread;

    char buff[512];

	char command[128];

    int fp_save = 0;

	int dev_num;



	dev_num = (int) args;

	sprintf(command, "stty -F /dev/ttyO%d 115200", dev_num);

	printf("set tty: %s\n", command);

    system(command);



	sprintf(command, "uart%d.data", dev_num);

    fp_save = open(command, O_WRONLY|O_CREAT|O_APPEND);

    if(fp_save == -1)

    {

        printf("open file err\n");

    }



	sprintf(command, "/dev/ttyO%d", dev_num);

    fd_uart = OpenDev(command);

    set_speed(fd_uart, 115200);

    if (set_Parity(fd_uart, 8, 1, 'N') == FALSE)

    {

        printf("Set Parity Error/n");

        return 0;

    }



    while(1)

    {

		memset(buff, 0, sizeof(buff));

		nread = read(fd_uart, buff, 16);

		if(nread > 0)

		{

			if(strstr(buff, FINISH_FLAG) != NULL )

			{

				printf("recv FINISH_FLAG so exit \n");

				break;

			}

			else

			{

				buff[nread] = '\0';

				write(fp_save, buff, nread);

				printf("receive ascii:%s receive byte:%d\n", buff, nread);

			}

		}

    }

	close(fp_save);

    close(fd_uart);

	return NULL;

}