串口0接收数据问题求助！！！

只看该作者 · 2010-8-9 21:42

最近研究w90p710串口通讯，看了下手册，发现有四个串口可以用，我选择了UART0来进行数据传输。telnetd到开发板上，进行操作，没有采用终端控制。
发送程序：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <string.h>

int main()
{
      int fd;
      int nwrite;
      struct termios oldtio,newtio;
      char buff[]="hello world";
      if((fd = open("/dev/ttyS0", O_RDWR|O_NOCTTY)) == -1)
      {
            perror("open");
            return -1;
      }
      printf("fd = %d\n",fd);

      tcgetattr(fd, &oldtio);
      cfsetispeed(&oldtio, B115200);
      cfsetospeed(&oldtio, B115200);

      bzero(&newtio, sizeof(newtio));

      newtio.c_cflag |= CS8;
      newtio.c_cflag &=~PARENB;
      newtio.c_iflag &=~INPCK;
      newtio.c_cflag &=~CSTOPB;

      newtio.c_cc[VTIME]=1;
      newtio.c_cc[VMIN]=0;

      tcflush(fd,TCIFLUSH);
      tcsetattr(fd,TCSANOW, &newtio);
      tcsetattr(fd, TCSANOW, &oldtio);

/*向串口写数据*/
      if((nwrite = write(fd,buff,sizeof(buff))) == -1)
      {
            perror("read");
            exit(EXIT_FAILURE);
      }

      //printf("%s\n",buff);
      return 0;
}
运行以后的结果是 fd = 3 然后等待

接收程序

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <string.h>

int main()
{
      int fd;
      int nread;
      struct termios oldtio,newtio;
      char buff[16];
      if((fd = open("/dev/ttyS0", O_RDWR|O_NOCTTY)) == -1)
      {
            perror("open");
            return -1;
      }
      printf("fd = %d\n",fd);

      tcgetattr(fd, &oldtio);
      cfsetispeed(&oldtio, B115200);
      cfsetospeed(&oldtio, B115200);

      bzero(&newtio, sizeof(newtio));

      newtio.c_cflag |= CS8;
      newtio.c_cflag &=~PARENB;
      newtio.c_iflag &=~INPCK;
      newtio.c_cflag &=~CSTOPB;

      newtio.c_cc[VTIME]=1;
      newtio.c_cc[VMIN]=0;

      tcflush(fd,TCIFLUSH);
      tcsetattr(fd,TCSANOW, &newtio);
      tcsetattr(fd, TCSANOW, &oldtio);

/*向串口读数据*/
      if((nread = read(fd,buff,sizeof(buff))) == -1)
      {
            perror("read");
            exit(EXIT_FAILURE);
      }

      printf("%s\n",buff);
      return 0;
}

运行后的结果 fd = 3 一直等待。

当我选择终端控制时，接收端运行后的结果是fd = 4，能打印发送端的发送过来的数据。

请问大虾，在不开启终端的情况下应该怎样修改程序，才能输出发送端传来的字符呢？

只看该作者 · 2010-8-11 18:01

要这样设定

tcgetattr(handle,&oldtio); /* save current modem settings */

/*
Set bps rate and hardware flow control and 8n1 (8bit,no parity,1 stopbit).
Also don't hangup automatically and ignore modem status.
Finally enable receiving characters.
*/
newtio.c_cflag = BAUDRATE | CS8 | CLOCAL | CREAD;

/*
Ignore bytes with parity errors and make terminal raw and dumb.
*/
newtio.c_iflag = IGNPAR;

/*
Raw output.
*/
newtio.c_oflag = 0;

/*
Don't echo characters because if you connect to a host it or your
modem will echo characters for you. Don't generate signals.
*/
newtio.c_lflag = 0;

/* blocking read until 1 char arrives */
newtio.c_cc[VMIN]=0;
newtio.c_cc[VTIME]=20;

/* now clean the modem line and activate the settings for modem */
tcflush(handle, TCIFLUSH);
tcsetattr(handle,TCSANOW,&newtio);
//cfsetospeed(&newtio,B38400);
if(!flag)
cfsetispeed(&newtio,BAUDRATE);
else
cfsetospeed(&newtio,BAUDRATE);

串口0接收数据问题求助！！！

相关下载

相关帖子