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分享关于LINUX的串口编程（解决问题者另开帖每人100-200分，UP有分！！！！！！！！！）
小弟最近在研究LINUX的串口编程，看过了《Linux 程序设计》和《Linux Serial Programming HOW-TO》上的有关串口编程的介绍。我试验着把COM1和COM2直接连接起来。稍微改编了一下lpg中miniterm.c，分成两个程序read_com.c和write_com.c。我分别在tty1和tty2运行这两个程序。令人不解的是这两个程序不能正常的通讯（我的COM1和COM2经测试，同一条线，在WINDOWS下是好的）。另外，为何两个程序的打开的文件描述符都是3？
read_com.c和write_com.c分别如下。望高手指点帮着解决这个问题，并希望再点拨小弟一下有关Linux串口编程的细节（我想用两个串口，每个控制一个设备）。如果有更详细的资料或者是代码请告诉小弟。谢谢！！
解决问题者另开帖每人100-200分（觉得不够可以再加，我都快被这个郁闷死了），UP有分
read_com.c和write_com.c分别如下。望高手指点帮着解决这个问题，并希望再点拨小弟一下有关Linux串口编程的细节（我想用两个串口，每个控制一个设备）。如果有更详细的资料或者是代码请告诉小弟。谢谢！！
解决问题者另开帖每人100-200分（觉得不够可以再加，我都快被这个郁闷死了），UP有分
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Ten0201 2003-06-10
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UP...可惜偶是菜鸟...不然....
wutong312 2003-06-10
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你载一个minicom工具，对串口直接进行初始化，然后对串口文件直接打开读写就行了，不知道你是不是需要这方面的知识，不用上面那么复杂，这样简单一点
kakafung 2003-06-10
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没发现前后给出的代码有什么区别啊
lpc007 2003-06-10
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up
hover_online 2003-06-09
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我们得东西也要用，多谢！
ljb130 2003-06-08
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up&gz
Joran 2003-06-08
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to Hobbytp(谭鹏) :
newtio.c_cflag = BAUDRATE | CRTSCTS | 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;
newtio.c_cflag = BAUDRATE | CRTSCTS | 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;
Hobbytp 2003-06-08
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我只想知道错在哪里，分倒不重要
Joran 2003-06-08
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大家还可以来拣分啊。：）
Joran 2003-06-08
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问题已经解决，Linux Serial Programming HOW-TO给的例子是错误的。
哈哈。
哈哈。
Joran 2003-05-31
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to fwbmail(斌) :
2, 3线交叉.windows 下可以正常收发信息.
2, 3线交叉.windows 下可以正常收发信息.
fwbmail 2003-05-31
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把两个com口直接连接，你的针脚也是对号连接的吗？我不太清楚具体的连接方式，不过我看到有
文章说，自己制作的COM线，需要变换阵脚的
文章说，自己制作的COM线，需要变换阵脚的
hitsmail 2003-05-30
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我也遇到同样的问题。我是在unix上测试都是可以读并可以写的，将程序改造到linux上就不能读和写了。
如果有详细的资料可以发送到我的信箱中！
lih@ffcs.fujitsu.co.jp
谢谢
关注中！
如果有详细的资料可以发送到我的信箱中！
lih@ffcs.fujitsu.co.jp
谢谢
关注中！
vcsongs 2003-05-30
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关注
Joran 2003-05-30
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当然是先设置好权限了。：（
我说的tty1和tty2是指virtual console（虚拟控制台）！
我说的tty1和tty2是指virtual console（虚拟控制台）！
lubaixu 2003-05-30
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好厉害呀.
我什么时候也可以这样高谈阔论.........
我什么时候也可以这样高谈阔论.........
Legend 2003-05-30
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另外，你前面说的是ttyS1和ttyS2，程序中却是0和1，不知道是否写错了。com1和com2应当是ttyS0和ttyS1，确定一下。
Legend 2003-05-30
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先 ll /dev/ttyS* 看看权限是不是设置好了
solar 2003-05-29
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gz
Joran 2003-05-29
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文件read_com.c 内容
/* File: read_com.c */
#include <termios.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/signal.h>
#define BAUDRATE B38400
#define MODEMDEVICE "/dev/ttyS0"
#define ENDMINITERM 2 /* ctrl-b to quit miniterm */
#define _POSIX_SOURCE 1 /* POSIX compliant source */
#define FALSE 0
#define TRUE 1
volatile int STOP = FALSE;
void child_handler(int s)
{
STOP = TRUE;
}
main()
{
int fd, c;
struct termios oldtio, newtio, oldstdtio, newstdtio;
struct sigaction sa;
/*
Open modem device for reading and writing and not as controlling tty
because we don't want to get killed if linenoise sends CTRL-C.
*/
fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY);
if (fd < 0) {
perror(MODEMDEVICE);
exit(-1);
}
tcgetattr(fd, &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 | CRTSCTS | 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] = 1;
newtio.c_cc[VTIME] = 0;
/* now clean the modem line and activate the settings for modem */
tcflush(fd, TCIFLUSH);
tcsetattr(fd, TCSANOW, &newtio);
/*
Strange, but if you uncomment this command miniterm will not work
even if you stop canonical mode for stdout. This is a linux bug.
*/
// tcsetattr(1, TCSANOW, &newtio); /* stdout settings like modem settings */
/* next stop echo and buffering for stdin */
tcgetattr(0, &oldstdtio);
tcgetattr(0, &newstdtio); /* get working stdtio */
newstdtio.c_lflag &= ~(ICANON | ECHO);
tcsetattr(0, TCSANOW, &newstdtio);
/* terminal settings done, now handle in/ouput */
switch (fork()) {
case 0: /* child */
/* user input */
//close(1); /* stdout not needed */
printf("Fork child process\n");
for (c = getchar(); c != ENDMINITERM; c = getchar()) {
write(fd, &c, 1);
printf("write %c to fd %d\n", c, fd);
}
tcsetattr(fd, TCSANOW, &oldtio); /* restore old modem setings */
tcsetattr(0, TCSANOW, &oldstdtio); /* restore old tty setings */
close(fd);
exit(0); /* will send a SIGCHLD to the parent */
break;
case -1:
perror("fork");
tcsetattr(fd, TCSANOW, &oldtio);
close(fd);
exit(-1);
default: /* parent */
//close(0); /* stdin not needed */
printf("Fork parent process\n");
sa.sa_handler = child_handler;
sa.sa_flags = 0;
sigaction(SIGCHLD, &sa, NULL); /* handle dying child */
while (STOP == FALSE) { /* modem input handler */
printf("Looping for read...\n");
read(fd, &c, 1); /* modem */
//write(1, &c, 1); /* stdout */
printf("receive %c\n", c);
}
wait(NULL); /* wait for child to die or it will become a zombie */
break;
}
}
/* File: read_com.c */
#include <termios.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/signal.h>
#define BAUDRATE B38400
#define MODEMDEVICE "/dev/ttyS0"
#define ENDMINITERM 2 /* ctrl-b to quit miniterm */
#define _POSIX_SOURCE 1 /* POSIX compliant source */
#define FALSE 0
#define TRUE 1
volatile int STOP = FALSE;
void child_handler(int s)
{
STOP = TRUE;
}
main()
{
int fd, c;
struct termios oldtio, newtio, oldstdtio, newstdtio;
struct sigaction sa;
/*
Open modem device for reading and writing and not as controlling tty
because we don't want to get killed if linenoise sends CTRL-C.
*/
fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY);
if (fd < 0) {
perror(MODEMDEVICE);
exit(-1);
}
tcgetattr(fd, &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 | CRTSCTS | 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] = 1;
newtio.c_cc[VTIME] = 0;
/* now clean the modem line and activate the settings for modem */
tcflush(fd, TCIFLUSH);
tcsetattr(fd, TCSANOW, &newtio);
/*
Strange, but if you uncomment this command miniterm will not work
even if you stop canonical mode for stdout. This is a linux bug.
*/
// tcsetattr(1, TCSANOW, &newtio); /* stdout settings like modem settings */
/* next stop echo and buffering for stdin */
tcgetattr(0, &oldstdtio);
tcgetattr(0, &newstdtio); /* get working stdtio */
newstdtio.c_lflag &= ~(ICANON | ECHO);
tcsetattr(0, TCSANOW, &newstdtio);
/* terminal settings done, now handle in/ouput */
switch (fork()) {
case 0: /* child */
/* user input */
//close(1); /* stdout not needed */
printf("Fork child process\n");
for (c = getchar(); c != ENDMINITERM; c = getchar()) {
write(fd, &c, 1);
printf("write %c to fd %d\n", c, fd);
}
tcsetattr(fd, TCSANOW, &oldtio); /* restore old modem setings */
tcsetattr(0, TCSANOW, &oldstdtio); /* restore old tty setings */
close(fd);
exit(0); /* will send a SIGCHLD to the parent */
break;
case -1:
perror("fork");
tcsetattr(fd, TCSANOW, &oldtio);
close(fd);
exit(-1);
default: /* parent */
//close(0); /* stdin not needed */
printf("Fork parent process\n");
sa.sa_handler = child_handler;
sa.sa_flags = 0;
sigaction(SIGCHLD, &sa, NULL); /* handle dying child */
while (STOP == FALSE) { /* modem input handler */
printf("Looping for read...\n");
read(fd, &c, 1); /* modem */
//write(1, &c, 1); /* stdout */
printf("receive %c\n", c);
}
wait(NULL); /* wait for child to die or it will become a zombie */
break;
}
}
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