板子的串口驱动有问题！求救啊！

fdds 2008-12-24 20:56 楼主

照着书上写的串口驱动测试程序，现在有问题了。
问题出现在下面这个程序当中！
series.c文件

#include "series.h"

int set_opt(int fd, int nSpeed, int nBits, char nEvent, int nStop)
{
struct termios newtio, oldtio;
if( (tcgetattr( fd, &oldtio ) ) != 0)
{
perror("SetupSerial 1");
return -1;
}
bzero( &newtio, sizeof( newtio ) );
newtio.c_cflag |= CLOCAL | CREAD;
newtio.c_cflag &= ~CSIZE;
switch( nBits )
{
case 7:
      newtio.c_cflag |= CS7;
    case 8:
      newtio.c_cflag |= CS8;
      break;
}

switch( nEvent )
{
case 'O':
      newtio.c_cflag |= PARENB;
      newtio.c_cflag |= PARODD;
      newtio.c_iflag |= (INPCK | ISTRIP);
      break;
case 'E':
      newtio.c_iflag |= (INPCK | ISTRIP);
      newtio.c_cflag |= PARENB;
      newtio.c_cflag &= ~PARODD;
      break;
case 'N':
      newtio.c_cflag &= ~PARENB;
      break;
}

switch( nSpeed )
{
case 2400:
      cfsetispeed( &newtio, B2400 );
      cfsetospeed( &newtio, B2400 );
      break;
case 4800:
      cfsetispeed( &newtio, B4800 );
      cfsetospeed( &newtio, B4800 );
      break;
case 9600:
      cfsetispeed( &newtio, B9600 );
      cfsetospeed( &newtio, B9600 );
      break;
case 115200:
      cfsetispeed( &newtio, B115200 );
      cfsetospeed( &newtio, B115200 );
      break;
case 460800:
      cfsetispeed( &newtio, B460800 );
      cfsetospeed( &newtio, B460800 );
      break;
default:
      cfsetispeed( &newtio, B9600);
      cfsetospeed( &newtio, B9600 );
      break;
}

if( nStop == 1 )
newtio.c_cflag &= ~CSTOPB;
else if( nStop == 2 )
newtio.c_cflag |= CSTOPB;

newtio.c_cc[VTIME] = 0;
newtio.c_cc[VMIN] = 0;
tcflush( fd, TCIFLUSH );
if( (tcsetattr( fd, TCSANOW, &newtio ) ) != 0)
{
perror(" com set error");
return -1;
}
printf("set done!\n");
return 0;
}
先在PC机上读写串口
lcw@series_driver>>> sudo ./gcc_write
fcntl = 0
isatty success!
fd-open = 3
set done!
fd=3
nwrite=8
lcw@series_driver>>>

lcw@series_driver>>> sudo ./gcc_read
fcntl = 0
isatty success!
fd-open = 3
set done!
nread = 8, Hello!

在PC机上可以读写取，现将读取函数交叉编译下载到板子上出现了问题
[root@lcw /home]#./arm_gcc_read
fcntl = 0
isatty success!
fd-open = 3
SetupSerial 1: Input/output error
set_opt error: Illegal seek
[root@lcw /home]#
[root@lcw /home]#./arm_gcc_write
fcntl = 0
isatty success!
fd-open = 3
SetupSerial 1: Input/output error
set_opt error: Illegal seek
[root@lcw /home]#

读取写入都出现了错误，据我分析问题是当下载到板子上时，读写函数在打开secies.c文件中的
tcgetattr( fd, &oldtio )时返回了负值，但是在PC机上是正确是，这是怎么回事呢？
请牛人们帮帮忙吧！