Linux系统串口接收数据编程
2017-03-21 20:41
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之前基于IBM deveplopworks社区的代码，做了串口初始化和发送的程序，今天在此基础上添加了读取串口数据的程序。首先是最简单的循环读取程序，第二个是通过软中断方式，使用信号signal机制读取串口，这里需要注意的是硬件中断是设备驱动层级的，而读写串口是用户级行为，只能通过信号机制模拟中断，信号机制的发生和处理其实于硬件中断无异，第三个是通过select系统调用，在没有数据时阻塞进程，串口有数据需要读时唤醒进程。第二个和第三个例子都能用来后台读取数据，值得学习。
代码一：循环读取数据
[cpp] view
plain copy
#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>
#define FALSE -1
#define TRUE 0
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;
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);
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; /* Enable parity */
options.c_cflag &= ~PARODD;
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);
}
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);
options.c_cc[VTIME] = 150;
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);
}
int main()
{
printf("This program updates last time at %s %s\n",__TIME__,__DATE__);
printf("STDIO COM1\n");
int fd;
fd = open("/dev/ttyS0",O_RDWR);
if(fd == -1)
{
perror("serialport error\n");
}
else
{
printf("open ");
printf("%s",ttyname(fd));
printf(" succesfully\n");
}
set_speed(fd,115200);
if (set_Parity(fd,8,1,'N') == FALSE) {
printf("Set Parity Error\n");
exit (0);
}
char buf[] = "fe55aa07bc010203040506073d";
write(fd,&buf,26);
char buff[512];
int nread;
while(1)
{
if((nread = read(fd, buff, 512))>0)
{
printf("\nLen: %d\n",nread);
buff[nread+1] = '\0';
printf("%s",buff);
}
}
close(fd);
return 0;
}
代码清单二：通过signal机制读取数据
[cpp] view
plain copy
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<sys/signal.h>
#include<fcntl.h>
#include<termios.h>
#include<errno.h>
#define FALSE -1
#define TRUE 0
#define flag 1
#define noflag 0
int wait_flag = noflag;
int STOP = 0;
int res;
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;
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);
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; /* Enable parity */
options.c_cflag &= ~PARODD;
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);
}
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);
options.c_cc[VTIME] = 150;
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);
}
void
signal_handler_IO (int status)
{
printf ("received SIGIO signale.\n");
wait_flag = noflag;
}
int
main ()
{
printf ("This program updates last time at %s %s\n", __TIME__, __DATE__);
printf ("STDIO COM1\n");
int fd;
struct sigaction saio;
fd = open ("/dev/ttyUSB0", O_RDWR);
if (fd == -1)
{
perror ("serialport error\n");
}
else
{
printf ("open ");
printf ("%s", ttyname (fd));
printf (" succesfully\n");
}
saio.sa_handler = signal_handler_IO;
sigemptyset (&saio.sa_mask);
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction (SIGIO, &saio, NULL);
//allow the process to receive SIGIO
fcntl (fd, F_SETOWN, getpid ());
//make the file descriptor asynchronous
fcntl (fd, F_SETFL, FASYNC);
set_speed (fd, 115200);
if (set_Parity (fd, 8, 1, 'N') == FALSE)
{
printf ("Set Parity Error\n");
exit (0);
}
char buf[255];
while (STOP == 0)
{
usleep (100000);
/* after receving SIGIO ,wait_flag = FALSE,input is availabe and can be read */
if (wait_flag == 0)
{
memset (buf, 0, sizeof(buf));
res = read (fd, buf, 255);
printf ("nread=%d,%s\n", res, buf);
// if (res ==1)
// STOP = 1; /*stop loop if only a CR was input */
wait_flag = flag; /*wait for new input */
}
}
close (fd);
return 0;
}
代码三：通过select系统调用进行io多路切换，实现异步读取串口数据
[python] view
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#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<sys/signal.h>
#include<fcntl.h>
#include<termios.h>
#include<errno.h>
#define FALSE -1
#define TRUE 0
#define flag 1
#define noflag 0
int wait_flag = noflag;
int STOP = 0;
int res;
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;
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);
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; /* Enable parity */
options.c_cflag &= ~PARODD;
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);
}
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);
options.c_cc[VTIME] = 150;
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);
}
void
signal_handler_IO (int status)
{
printf ("received SIGIO signale.\n");
wait_flag = noflag;
}
int
main ()
{
printf ("This program updates last time at %s %s\n", __TIME__, __DATE__);
printf ("STDIO COM1\n");
int fd;
fd = open ("/dev/ttyUSB0", O_RDWR);
if (fd == -1)
{
perror ("serialport error\n");
}
else
{
printf ("open ");
printf ("%s", ttyname (fd));
printf (" succesfully\n");
}
set_speed (fd, 115200);
if (set_Parity (fd, 8, 1, 'N') == FALSE)
{
printf ("Set Parity Error\n");
exit (0);
}
char buf[255];
fd_set rd;
int nread = 0;
while(1)
{
FD_ZERO(&rd);
FD_SET(fd, &rd);
while(FD_ISSET(fd, &rd))
{
if(select(fd+1, &rd, NULL,NULL,NULL) < 0)
{
perror("select error\n");
}
else
{
while((nread = read(fd, buf, sizeof(buf))) > 0)
{
printf("nread = %d,%s\n",nread, buf);
printf("test\n");
memset(buf, 0 , sizeof(buf));
}
}
}
}
close (fd);
return 0;
}
代码一：循环读取数据
[cpp] view
plain copy
#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>
#define FALSE -1
#define TRUE 0
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;
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);
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; /* Enable parity */
options.c_cflag &= ~PARODD;
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);
}
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);
options.c_cc[VTIME] = 150;
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);
}
int main()
{
printf("This program updates last time at %s %s\n",__TIME__,__DATE__);
printf("STDIO COM1\n");
int fd;
fd = open("/dev/ttyS0",O_RDWR);
if(fd == -1)
{
perror("serialport error\n");
}
else
{
printf("open ");
printf("%s",ttyname(fd));
printf(" succesfully\n");
}
set_speed(fd,115200);
if (set_Parity(fd,8,1,'N') == FALSE) {
printf("Set Parity Error\n");
exit (0);
}
char buf[] = "fe55aa07bc010203040506073d";
write(fd,&buf,26);
char buff[512];
int nread;
while(1)
{
if((nread = read(fd, buff, 512))>0)
{
printf("\nLen: %d\n",nread);
buff[nread+1] = '\0';
printf("%s",buff);
}
}
close(fd);
return 0;
}
代码清单二：通过signal机制读取数据
[cpp] view
plain copy
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<sys/signal.h>
#include<fcntl.h>
#include<termios.h>
#include<errno.h>
#define FALSE -1
#define TRUE 0
#define flag 1
#define noflag 0
int wait_flag = noflag;
int STOP = 0;
int res;
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;
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);
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; /* Enable parity */
options.c_cflag &= ~PARODD;
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);
}
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);
options.c_cc[VTIME] = 150;
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);
}
void
signal_handler_IO (int status)
{
printf ("received SIGIO signale.\n");
wait_flag = noflag;
}
int
main ()
{
printf ("This program updates last time at %s %s\n", __TIME__, __DATE__);
printf ("STDIO COM1\n");
int fd;
struct sigaction saio;
fd = open ("/dev/ttyUSB0", O_RDWR);
if (fd == -1)
{
perror ("serialport error\n");
}
else
{
printf ("open ");
printf ("%s", ttyname (fd));
printf (" succesfully\n");
}
saio.sa_handler = signal_handler_IO;
sigemptyset (&saio.sa_mask);
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction (SIGIO, &saio, NULL);
//allow the process to receive SIGIO
fcntl (fd, F_SETOWN, getpid ());
//make the file descriptor asynchronous
fcntl (fd, F_SETFL, FASYNC);
set_speed (fd, 115200);
if (set_Parity (fd, 8, 1, 'N') == FALSE)
{
printf ("Set Parity Error\n");
exit (0);
}
char buf[255];
while (STOP == 0)
{
usleep (100000);
/* after receving SIGIO ,wait_flag = FALSE,input is availabe and can be read */
if (wait_flag == 0)
{
memset (buf, 0, sizeof(buf));
res = read (fd, buf, 255);
printf ("nread=%d,%s\n", res, buf);
// if (res ==1)
// STOP = 1; /*stop loop if only a CR was input */
wait_flag = flag; /*wait for new input */
}
}
close (fd);
return 0;
}
代码三：通过select系统调用进行io多路切换，实现异步读取串口数据
[python] view
plain copy
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<sys/signal.h>
#include<fcntl.h>
#include<termios.h>
#include<errno.h>
#define FALSE -1
#define TRUE 0
#define flag 1
#define noflag 0
int wait_flag = noflag;
int STOP = 0;
int res;
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;
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);
options.c_iflag |= INPCK; /* Disnable parity checking */
break;
case 'e':
case 'E':
options.c_cflag |= PARENB; /* Enable parity */
options.c_cflag &= ~PARODD;
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);
}
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);
options.c_cc[VTIME] = 150;
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);
}
void
signal_handler_IO (int status)
{
printf ("received SIGIO signale.\n");
wait_flag = noflag;
}
int
main ()
{
printf ("This program updates last time at %s %s\n", __TIME__, __DATE__);
printf ("STDIO COM1\n");
int fd;
fd = open ("/dev/ttyUSB0", O_RDWR);
if (fd == -1)
{
perror ("serialport error\n");
}
else
{
printf ("open ");
printf ("%s", ttyname (fd));
printf (" succesfully\n");
}
set_speed (fd, 115200);
if (set_Parity (fd, 8, 1, 'N') == FALSE)
{
printf ("Set Parity Error\n");
exit (0);
}
char buf[255];
fd_set rd;
int nread = 0;
while(1)
{
FD_ZERO(&rd);
FD_SET(fd, &rd);
while(FD_ISSET(fd, &rd))
{
if(select(fd+1, &rd, NULL,NULL,NULL) < 0)
{
perror("select error\n");
}
else
{
while((nread = read(fd, buf, sizeof(buf))) > 0)
{
printf("nread = %d,%s\n",nread, buf);
printf("test\n");
memset(buf, 0 , sizeof(buf));
}
}
}
}
close (fd);
return 0;
}
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