如何用中断串口读取串口？
How to read serial with interrupt serial?
我正在尝试阅读 Linux 中的 NMEA 消息。但是我无法得到完整的消息：
54.441,V,,,,,0.00,0.00,010720,,,N*42
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32
$GPGGA,020954.441,,,,,0,0,,,M,,M,,*43
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79
$GLGSV,1,1,00*65
$GPGLL,,,,,020954.441,V,N*71
$GP
第一行和最后一行是一条消息，但已拆分。我的事情，这是由睡眠 1 秒引起的。这根本不对。我想我应该使用中断串行。
我的想法是当数据进来时，中断串行将 运行 一个读取串行并处理它的函数。之后，系统将休眠直到下一条消息。我搜索了一些 material 但没有帮助。
这是我的新代码，它不起作用：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <errno.h>
#include <termios.h>
void signal_handler_IO ();
int fd;
int connected;
struct termios termAttr;
struct sigaction saio;
int main(int argc, char *argv[])
{
fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1)
{
perror("open_port: Unable to open port\n");
exit(1);
}
saio.sa_handler = signal_handler_IO;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO,&saio,NULL);
fcntl(fd, F_SETFL, FNDELAY);
fcntl(fd, F_SETOWN, getpid());
fcntl(fd, F_SETFL, O_ASYNC );
tcgetattr(fd,&termAttr);
cfsetispeed(&termAttr,B9600);
cfsetospeed(&termAttr,B9600);
termAttr.c_cflag &= ~PARENB;
termAttr.c_cflag &= ~CSTOPB;
termAttr.c_cflag &= ~CSIZE;
termAttr.c_cflag |= CS8;
termAttr.c_cflag |= (CLOCAL | CREAD);
termAttr.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
termAttr.c_iflag &= ~(IXON | IXOFF | IXANY);
termAttr.c_oflag &= ~OPOST;
tcsetattr(fd,TCSANOW,&termAttr);
printf("UART1 configured....\n");
while(1){
sleep(1);
}
close(fd);
exit(0);
}
void signal_handler_IO ()
{
FILE *csv;
char buff [1024];
int n = read(fd, &buff, sizeof(buff));
char * token = strtok(buff, ",");
csv=fopen("csvfile.csv","w");
while( token != NULL ) {
fprintf(csv,"%s\n",token);
token = strtok(NULL, ",");
}
fclose(csv);
}
我现在该怎么办？
NMEA 消息为 行 ，以 '\n'.
结尾
将read()更改为fgets()（使用fopen()打开）并作为行读入字符串 用于稍后 strtok() 处理。
另请参阅 个想法。
这是我的最高评论。
thank you for your positive response. Did you mean I should use read() function like my old code ? And actually, I have never working with select before. But I very interesting with your idea. And I hope you can show me more the way which apply on my case.
好的，这是一个不使用信号处理程序的简单[且未经测试]的版本。而且，我使用 poll 而不是 select [它们很相似] 因为它更容易使用。
请注意，您使用 O_NDELAY 打开了 TTY 设备文件，因此 read 调用是非阻塞的。
另请注意，打开的设备将不会产生 EOF 条件，无论是您的方式还是我的方式。
因此，您必须使用代码来查找表示最后一行的行（例如 $GP）。
或者，在循环中第一次初始等待之后，后续超时应该表明不再有输入
无论如何，这是代码：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <errno.h>
#include <termios.h>
#if 1
#include <poll.h>
#endif
void signal_handler_IO(); /* definition of signal handler */
int fd;
struct termios termAttr;
struct sigaction saio;
struct pollfd fdpoll;
int
main(int argc, char *argv[])
{
int timout;
FILE *fout = NULL;
int buf_has_GP = 0;
int lastchr = -1;
int curchr;
int err;
int rlen;
int idx;
char buf[1000];
fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror("open_port: Unable to open port\n");
exit(1);
}
#if 0
saio.sa_handler = signal_handler_IO;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO, &saio, NULL);
#endif
fcntl(fd, F_SETFL, FNDELAY);
fcntl(fd, F_SETOWN, getpid());
fcntl(fd, F_SETFL, O_ASYNC);
tcgetattr(fd, &termAttr);
cfsetispeed(&termAttr, B9600);
cfsetospeed(&termAttr, B9600);
termAttr.c_cflag &= ~PARENB;
termAttr.c_cflag &= ~CSTOPB;
termAttr.c_cflag &= ~CSIZE;
termAttr.c_cflag |= CS8;
termAttr.c_cflag |= (CLOCAL | CREAD);
termAttr.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
termAttr.c_iflag &= ~(IXON | IXOFF | IXANY);
termAttr.c_oflag &= ~OPOST;
tcsetattr(fd, TCSANOW, &termAttr);
printf("UART1 configured....\n");
fout = fopen("csvfile.csv","w");
fdpoll.fd = fd;
fdpoll.events = POLLIN;
timout = 10000;
while (1) {
err = poll(&fdpoll,1,timout);
// timeout
if (err == 0)
break;
// error
if (err < 0) {
fprintf(stderr,"error -- %s\n",strerror(errno));
break;
}
// err will always be _one_ because poll's second arg is 1
while (1) {
rlen = read(fd,buf,sizeof(buf));
if (rlen <= 0)
break;
fwrite(buf,1,rlen,fout);
// need to check buf looking for last line (e.g. $GP)
// to know when to stop
// since read is _not_ line oriented we have to check for G followed
// by P [and they may or may not occur in the same read call]
// FIXME -- this is quite crude -- just to illustrate
for (idx = 0; idx < rlen; ++idx) {
curchr = buf[idx];
buf_has_GP = ((lastchr == 'G') && (curchr == 'P'));
if (buf_has_GP)
break;
lastchr = curchr;
}
if (buf_has_GP)
break;
}
if (buf_has_GP)
break;
timout = 1000;
#if 0
sleep(1);
#endif
}
close(fd);
fclose(fout);
exit(0);
}
void
signal_handler_IO()
{
FILE *csv;
FILE *ff;
char buff[1024];
ff = fopen("/dev/ttyUSB0", "r");
// int n = read(fd, &buff, sizeof(buff));
fgets(buff, sizeof(buff), ff);
char *token = strtok(buff, ",");
csv = fopen("csvfile.csv", "w");
while (token != NULL) {
fprintf(csv, "%s\n", token);
token = strtok(NULL, ",");
}
sleep(0.2);
fclose(csv);
}
更新：
Thank you so much for spend your time for me. I compiled it without error. Unfortunately, I get nothing from output and empty file.
这可能是因为simple/crude EOF字符串检测代码。我认为它可能过早地停止了。我添加了更强大的检查。
我还添加了调试打印（如果给出 -d）。
因为我无法访问真正的 ttyUSB 设备，所以我使用 PTY [伪 TTY] 添加了测试代码。要使用它，请将示例 NMEA 数据放入文件中（例如 input.txt）并将 -pinput.txt 添加到参数中。
这就是我调试一般程序流程的方式。
我已经关闭了所有不必要的 fcntl 选项。
如果尝试此操作后仍有问题，您可能希望使用终端程序（例如 minicom）测试您的设备接口，以验证远程设备确实在发送数据。
如果 minicom 产生输出，但您的程序没有，您可能需要修改某些 termios 选项。
一些usbtty/uart设备需要RTS/CTS[我实际上已经使用这样的设备工作]。 minicom 有一个配置选项来处理这个问题。
在程序中[虽然我怀疑它默认是关闭]，你可能需要禁用RTS/CTS硬件，这样端口才不会被挂断。 And/or 确保 XON/XOFF 流量控制被禁用。
或者，远程设备需要 RTS/CTS支持[你必须以某种方式强制远程设备看到 CTS 高]。虽然不太可能，但 可能 必须在电缆本身中完成。
无论如何，这是更新后的代码：
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <errno.h>
#include <termios.h>
#if 1
#include <poll.h>
#include <pty.h>
#include <sys/wait.h>
#include <time.h>
#endif
#ifndef RAWOUT
#define RAWOUT 1
#endif
void signal_handler_IO(); /* definition of signal handler */
const char *ttydev = "/dev/ttyUSB0";
int fd;
int opt_d; // 1=debug print
char *opt_pty; // PTY input file
int ptypid;
#define PTYSLP 1
FILE *fout = NULL;
struct termios termAttr;
struct sigaction saio;
struct pollfd fdpoll;
int linelen;
char linebuf[1000];
#define SHOWPOLL(_msk) \
if (events & _msk) \
bp += sprintf(bp,"/" #_msk)
typedef long long tsc_t;
tsc_t
tscget(void)
{
struct timespec ts;
tsc_t tsc;
static tsc_t tsczero = 0;
clock_gettime(CLOCK_REALTIME,&ts);
tsc = ts.tv_sec;
tsc *= 1000000000;
tsc += ts.tv_nsec;
if (tsczero == 0)
tsczero = tsc;
tsc -= tsczero;
return tsc;
}
double
tscsec(tsc_t tsc)
{
double sec;
sec = tsc;
sec /= 1e9;
return sec;
}
void
tscprt(void)
{
tsc_t tsc;
tsc = tscget();
printf("%.9f ",tscsec(tsc));
}
#define dbgprt(_fmt...) \
do { \
if (! opt_d) \
break; \
int sverr = errno; \
tscprt(); \
printf(_fmt); \
errno = sverr; \
} while (0)
// dopty -- generate pseudo TTY test device
void
dopty(void)
{
int fdm;
int fdtxt;
int rlen;
int wlen;
int off;
char buf[1000];
#if 0
fdm = open("/dev/pts/ptmx",O_RDWR | O_NDELAY);
#else
fdm = getpt();
#endif
if (fdm < 0) {
perror("dopty/open");
exit(1);
}
dbgprt("dopty: GETPT fdm=%d\n",fdm);
ttydev = ptsname(fdm);
dbgprt("dopty: PTSNAME ttydev=%s\n",ttydev);
grantpt(fdm);
unlockpt(fdm);
dbgprt("dopty: INPUT opt_pty=%s\n",opt_pty);
do {
ptypid = fork();
if (ptypid != 0) {
close(fdm);
break;
}
// open sample test data file
fdtxt = open(opt_pty,O_RDONLY);
if (fdtxt < 0) {
perror("dopty/open");
exit(1);
}
sleep(PTYSLP);
while (1) {
rlen = read(fdtxt,buf,sizeof(buf));
if (rlen <= 0)
break;
dbgprt("dopty: READ rlen=%d\n",rlen);
for (off = 0; off < rlen; off += wlen) {
wlen = rlen - off;
wlen = write(fdm,&buf[off],wlen);
dbgprt("dopty: WRITE wlen=%d\n",wlen);
}
}
sleep(PTYSLP);
dbgprt("dopty: CLOSE\n");
close(fdtxt);
close(fdm);
sleep(PTYSLP);
dbgprt("dopty: EXIT\n");
exit(0);
} while (0);
}
char *
showpoll(short events)
{
char *bp;
static char buf[1000];
bp = buf;
bp += sprintf(bp,"%4.4X",events);
SHOWPOLL(POLLIN);
SHOWPOLL(POLLPRI);
SHOWPOLL(POLLOUT);
SHOWPOLL(POLLRDHUP);
SHOWPOLL(POLLERR);
SHOWPOLL(POLLHUP);
return buf;
}
// lineadd -- add character to line buffer
void
lineadd(int chr)
{
char *bp;
char buf[10];
if (opt_d) {
bp = buf;
*bp = 0;
if ((chr >= 0x20) && (chr <= 0x7E))
bp += sprintf(bp," '%c'",chr);
dbgprt("showchr: CHR chr=%2.2X%s\n",chr,buf);
}
linebuf[linelen++] = chr;
linebuf[linelen] = 0;
}
// eoftst -- decide if current line is the last line
int
eoftst(void)
{
static char *eofstr = "$GP\n";
static int eoflen = 0;
int stopflg = 0;
if (eoflen == 0)
eoflen = strlen(eofstr);
stopflg = ((linelen == eoflen) && (memcmp(linebuf,eofstr,eoflen) == 0));
dbgprt("eoftst: %s\n",stopflg ? "STOP" : "CONT");
return stopflg;
}
int
main(int argc, char **argv)
{
int timout;
int buf_has_eof = 0;
int curchr;
int err;
int rlen;
int idx;
char buf[1000];
--argc;
++argv;
setlinebuf(stdout);
setlinebuf(stderr);
for (; argc > 0; --argc, ++argv) {
char *cp = *argv;
if (*cp != '-')
break;
cp += 2;
switch (cp[-1]) {
case 'd':
opt_d = ! opt_d;
break;
case 'p':
opt_pty = (*cp != 0) ? cp : "input.txt";
break;
}
}
do {
// create test device
if (opt_pty != NULL) {
dopty();
break;
}
if (argc > 0) {
ttydev = *argv;
--argc;
++argv;
}
} while (0);
dbgprt("main: TTYDEV ttydev=%s\n",ttydev);
fd = open(ttydev, O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror("open_port: Unable to open port\n");
exit(1);
}
#if 0
saio.sa_handler = signal_handler_IO;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO, &saio, NULL);
#endif
// not needed unless doing signal handler
#if 0
fcntl(fd, F_SETFL, FNDELAY);
fcntl(fd, F_SETOWN, getpid());
fcntl(fd, F_SETFL, O_ASYNC);
#endif
#if 1
tcgetattr(fd, &termAttr);
#endif
#if 1
cfsetispeed(&termAttr, B9600);
cfsetospeed(&termAttr, B9600);
#endif
// force immediate return from device read if no chars available
#if 1
dbgprt("main: CC VMIN=%d VTIME=%d\n",
termAttr.c_cc[VMIN],termAttr.c_cc[VTIME]);
termAttr.c_cc[VMIN] = 0;
termAttr.c_cc[VTIME] = 0;
#endif
termAttr.c_cflag &= ~PARENB;
termAttr.c_cflag &= ~CSTOPB;
termAttr.c_cflag &= ~CSIZE;
termAttr.c_cflag |= CS8;
termAttr.c_cflag |= (CLOCAL | CREAD);
// FIXME -- you may need to handle this
#if 1
termAttr.c_cflag &= ~CRTSCTS;
#else
termAttr.c_cflag |= CRTSCTS;
#endif
termAttr.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
termAttr.c_iflag &= ~(IXON | IXOFF | IXANY);
termAttr.c_oflag &= ~OPOST;
#if 1
tcsetattr(fd, TCSANOW, &termAttr);
#endif
printf("UART1 configured....\n");
// open output file
fout = fopen("csvfile.csv","w");
if (fout == NULL) {
perror("main/fopen");
exit(1);
}
fdpoll.fd = fd;
fdpoll.events = POLLIN;
fdpoll.revents = 0;
// set initial timeout of 10 seconds
timout = 10000;
// NOTE: iter is just for testing to prevent infinite looping if failure to
// read or match the EOF string
for (int iter = 1; iter < 10; ++iter) {
dbgprt("main: POLL iter=%d events=%s timout=%d\n",
iter,showpoll(fdpoll.events),timout);
err = poll(&fdpoll,1,timout);
dbgprt("main: POLL revents=%s err=%d\n",showpoll(fdpoll.revents),err);
// timeout
if (err == 0)
break;
// error
if (err < 0) {
fprintf(stderr,"error -- %s\n",strerror(errno));
break;
}
// err will always be _one_ because poll's second arg is 1
// process all data in current chunk
while (1) {
rlen = read(fd,buf,sizeof(buf));
dbgprt("main: READ iter=%d rlen=%d\n",iter,rlen);
if (rlen <= 0)
break;
// send data to output file
#if RAWOUT
fwrite(buf,1,rlen,fout);
#endif
// need to check buf looking for last line (e.g. $GP)
// to know when to stop
// since read is _not_ line oriented we have to check for G followed
// by P [and they may or may not occur in the same read call]
// FIXME -- this is quite crude -- just to illustrate
for (idx = 0; idx < rlen; ++idx) {
curchr = buf[idx];
// add to line buffer
lineadd(curchr);
// wait for newline
if (curchr != '\n')
continue;
// decide if this is the last line of the current NMEA message
buf_has_eof = eoftst();
#if (! RAWOUT)
// do processing on line buffer ...
#endif
// reset line buffer index/length for next line
linelen = 0;
if (buf_has_eof)
break;
}
if (buf_has_eof)
break;
}
if (buf_has_eof)
break;
// set 1 second timeout for subsequent reads
timout = 1000;
#if 0
sleep(1);
#endif
}
close(fd);
fclose(fout);
// reap any child processes [only if doing PTY mode]
while (opt_pty != NULL) {
pid_t pid = wait(NULL);
dbgprt("main: WAIT pid=%d\n",pid);
if (pid <= 0)
break;
}
exit(0);
}
void
signal_handler_IO()
{
FILE *csv;
FILE *ff;
char buff[1024];
ff = fopen("/dev/ttyUSB0", "r");
// int n = read(fd, &buff, sizeof(buff));
fgets(buff, sizeof(buff), ff);
char *token = strtok(buff, ",");
csv = fopen("csvfile.csv", "w");
while (token != NULL) {
fprintf(csv, "%s\n", token);
token = strtok(NULL, ",");
}
sleep(0.2);
fclose(csv);
}
我正在尝试阅读 Linux 中的 NMEA 消息。但是我无法得到完整的消息：
54.441,V,,,,,0.00,0.00,010720,,,N*42
$GPVTG,0.00,T,,M,0.00,N,0.00,K,N*32
$GPGGA,020954.441,,,,,0,0,,,M,,M,,*43
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79
$GLGSV,1,1,00*65
$GPGLL,,,,,020954.441,V,N*71
$GP
第一行和最后一行是一条消息，但已拆分。我的事情，这是由睡眠 1 秒引起的。这根本不对。我想我应该使用中断串行。
我的想法是当数据进来时，中断串行将 运行 一个读取串行并处理它的函数。之后，系统将休眠直到下一条消息。我搜索了一些 material 但没有帮助。
这是我的新代码，它不起作用：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <errno.h>
#include <termios.h>
void signal_handler_IO ();
int fd;
int connected;
struct termios termAttr;
struct sigaction saio;
int main(int argc, char *argv[])
{
fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1)
{
perror("open_port: Unable to open port\n");
exit(1);
}
saio.sa_handler = signal_handler_IO;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO,&saio,NULL);
fcntl(fd, F_SETFL, FNDELAY);
fcntl(fd, F_SETOWN, getpid());
fcntl(fd, F_SETFL, O_ASYNC );
tcgetattr(fd,&termAttr);
cfsetispeed(&termAttr,B9600);
cfsetospeed(&termAttr,B9600);
termAttr.c_cflag &= ~PARENB;
termAttr.c_cflag &= ~CSTOPB;
termAttr.c_cflag &= ~CSIZE;
termAttr.c_cflag |= CS8;
termAttr.c_cflag |= (CLOCAL | CREAD);
termAttr.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
termAttr.c_iflag &= ~(IXON | IXOFF | IXANY);
termAttr.c_oflag &= ~OPOST;
tcsetattr(fd,TCSANOW,&termAttr);
printf("UART1 configured....\n");
while(1){
sleep(1);
}
close(fd);
exit(0);
}
void signal_handler_IO ()
{
FILE *csv;
char buff [1024];
int n = read(fd, &buff, sizeof(buff));
char * token = strtok(buff, ",");
csv=fopen("csvfile.csv","w");
while( token != NULL ) {
fprintf(csv,"%s\n",token);
token = strtok(NULL, ",");
}
fclose(csv);
}
我现在该怎么办？
NMEA 消息为 行 ，以 '\n'.
将read()更改为fgets()（使用fopen()打开）并作为行读入字符串 用于稍后 strtok() 处理。
另请参阅
这是我的最高评论。
thank you for your positive response. Did you mean I should use
read()function like my old code ? And actually, I have never working withselectbefore. But I very interesting with your idea. And I hope you can show me more the way which apply on my case.
好的，这是一个不使用信号处理程序的简单[且未经测试]的版本。而且，我使用 poll 而不是 select [它们很相似] 因为它更容易使用。
请注意，您使用 O_NDELAY 打开了 TTY 设备文件，因此 read 调用是非阻塞的。
另请注意，打开的设备将不会产生 EOF 条件，无论是您的方式还是我的方式。
因此，您必须使用代码来查找表示最后一行的行（例如 $GP）。
或者，在循环中第一次初始等待之后，后续超时应该表明不再有输入
无论如何，这是代码：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <errno.h>
#include <termios.h>
#if 1
#include <poll.h>
#endif
void signal_handler_IO(); /* definition of signal handler */
int fd;
struct termios termAttr;
struct sigaction saio;
struct pollfd fdpoll;
int
main(int argc, char *argv[])
{
int timout;
FILE *fout = NULL;
int buf_has_GP = 0;
int lastchr = -1;
int curchr;
int err;
int rlen;
int idx;
char buf[1000];
fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror("open_port: Unable to open port\n");
exit(1);
}
#if 0
saio.sa_handler = signal_handler_IO;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO, &saio, NULL);
#endif
fcntl(fd, F_SETFL, FNDELAY);
fcntl(fd, F_SETOWN, getpid());
fcntl(fd, F_SETFL, O_ASYNC);
tcgetattr(fd, &termAttr);
cfsetispeed(&termAttr, B9600);
cfsetospeed(&termAttr, B9600);
termAttr.c_cflag &= ~PARENB;
termAttr.c_cflag &= ~CSTOPB;
termAttr.c_cflag &= ~CSIZE;
termAttr.c_cflag |= CS8;
termAttr.c_cflag |= (CLOCAL | CREAD);
termAttr.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
termAttr.c_iflag &= ~(IXON | IXOFF | IXANY);
termAttr.c_oflag &= ~OPOST;
tcsetattr(fd, TCSANOW, &termAttr);
printf("UART1 configured....\n");
fout = fopen("csvfile.csv","w");
fdpoll.fd = fd;
fdpoll.events = POLLIN;
timout = 10000;
while (1) {
err = poll(&fdpoll,1,timout);
// timeout
if (err == 0)
break;
// error
if (err < 0) {
fprintf(stderr,"error -- %s\n",strerror(errno));
break;
}
// err will always be _one_ because poll's second arg is 1
while (1) {
rlen = read(fd,buf,sizeof(buf));
if (rlen <= 0)
break;
fwrite(buf,1,rlen,fout);
// need to check buf looking for last line (e.g. $GP)
// to know when to stop
// since read is _not_ line oriented we have to check for G followed
// by P [and they may or may not occur in the same read call]
// FIXME -- this is quite crude -- just to illustrate
for (idx = 0; idx < rlen; ++idx) {
curchr = buf[idx];
buf_has_GP = ((lastchr == 'G') && (curchr == 'P'));
if (buf_has_GP)
break;
lastchr = curchr;
}
if (buf_has_GP)
break;
}
if (buf_has_GP)
break;
timout = 1000;
#if 0
sleep(1);
#endif
}
close(fd);
fclose(fout);
exit(0);
}
void
signal_handler_IO()
{
FILE *csv;
FILE *ff;
char buff[1024];
ff = fopen("/dev/ttyUSB0", "r");
// int n = read(fd, &buff, sizeof(buff));
fgets(buff, sizeof(buff), ff);
char *token = strtok(buff, ",");
csv = fopen("csvfile.csv", "w");
while (token != NULL) {
fprintf(csv, "%s\n", token);
token = strtok(NULL, ",");
}
sleep(0.2);
fclose(csv);
}
更新：
Thank you so much for spend your time for me. I compiled it without error. Unfortunately, I get nothing from output and empty file.
这可能是因为simple/crude EOF字符串检测代码。我认为它可能过早地停止了。我添加了更强大的检查。
我还添加了调试打印（如果给出 -d）。
因为我无法访问真正的 ttyUSB 设备，所以我使用 PTY [伪 TTY] 添加了测试代码。要使用它，请将示例 NMEA 数据放入文件中（例如 input.txt）并将 -pinput.txt 添加到参数中。
这就是我调试一般程序流程的方式。
我已经关闭了所有不必要的 fcntl 选项。
如果尝试此操作后仍有问题，您可能希望使用终端程序（例如 minicom）测试您的设备接口，以验证远程设备确实在发送数据。
如果 minicom 产生输出，但您的程序没有，您可能需要修改某些 termios 选项。
一些usbtty/uart设备需要RTS/CTS[我实际上已经使用这样的设备工作]。 minicom 有一个配置选项来处理这个问题。
在程序中[虽然我怀疑它默认是关闭]，你可能需要禁用RTS/CTS硬件，这样端口才不会被挂断。 And/or 确保 XON/XOFF 流量控制被禁用。
或者，远程设备需要 RTS/CTS支持[你必须以某种方式强制远程设备看到 CTS 高]。虽然不太可能，但 可能 必须在电缆本身中完成。
无论如何，这是更新后的代码：
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <errno.h>
#include <termios.h>
#if 1
#include <poll.h>
#include <pty.h>
#include <sys/wait.h>
#include <time.h>
#endif
#ifndef RAWOUT
#define RAWOUT 1
#endif
void signal_handler_IO(); /* definition of signal handler */
const char *ttydev = "/dev/ttyUSB0";
int fd;
int opt_d; // 1=debug print
char *opt_pty; // PTY input file
int ptypid;
#define PTYSLP 1
FILE *fout = NULL;
struct termios termAttr;
struct sigaction saio;
struct pollfd fdpoll;
int linelen;
char linebuf[1000];
#define SHOWPOLL(_msk) \
if (events & _msk) \
bp += sprintf(bp,"/" #_msk)
typedef long long tsc_t;
tsc_t
tscget(void)
{
struct timespec ts;
tsc_t tsc;
static tsc_t tsczero = 0;
clock_gettime(CLOCK_REALTIME,&ts);
tsc = ts.tv_sec;
tsc *= 1000000000;
tsc += ts.tv_nsec;
if (tsczero == 0)
tsczero = tsc;
tsc -= tsczero;
return tsc;
}
double
tscsec(tsc_t tsc)
{
double sec;
sec = tsc;
sec /= 1e9;
return sec;
}
void
tscprt(void)
{
tsc_t tsc;
tsc = tscget();
printf("%.9f ",tscsec(tsc));
}
#define dbgprt(_fmt...) \
do { \
if (! opt_d) \
break; \
int sverr = errno; \
tscprt(); \
printf(_fmt); \
errno = sverr; \
} while (0)
// dopty -- generate pseudo TTY test device
void
dopty(void)
{
int fdm;
int fdtxt;
int rlen;
int wlen;
int off;
char buf[1000];
#if 0
fdm = open("/dev/pts/ptmx",O_RDWR | O_NDELAY);
#else
fdm = getpt();
#endif
if (fdm < 0) {
perror("dopty/open");
exit(1);
}
dbgprt("dopty: GETPT fdm=%d\n",fdm);
ttydev = ptsname(fdm);
dbgprt("dopty: PTSNAME ttydev=%s\n",ttydev);
grantpt(fdm);
unlockpt(fdm);
dbgprt("dopty: INPUT opt_pty=%s\n",opt_pty);
do {
ptypid = fork();
if (ptypid != 0) {
close(fdm);
break;
}
// open sample test data file
fdtxt = open(opt_pty,O_RDONLY);
if (fdtxt < 0) {
perror("dopty/open");
exit(1);
}
sleep(PTYSLP);
while (1) {
rlen = read(fdtxt,buf,sizeof(buf));
if (rlen <= 0)
break;
dbgprt("dopty: READ rlen=%d\n",rlen);
for (off = 0; off < rlen; off += wlen) {
wlen = rlen - off;
wlen = write(fdm,&buf[off],wlen);
dbgprt("dopty: WRITE wlen=%d\n",wlen);
}
}
sleep(PTYSLP);
dbgprt("dopty: CLOSE\n");
close(fdtxt);
close(fdm);
sleep(PTYSLP);
dbgprt("dopty: EXIT\n");
exit(0);
} while (0);
}
char *
showpoll(short events)
{
char *bp;
static char buf[1000];
bp = buf;
bp += sprintf(bp,"%4.4X",events);
SHOWPOLL(POLLIN);
SHOWPOLL(POLLPRI);
SHOWPOLL(POLLOUT);
SHOWPOLL(POLLRDHUP);
SHOWPOLL(POLLERR);
SHOWPOLL(POLLHUP);
return buf;
}
// lineadd -- add character to line buffer
void
lineadd(int chr)
{
char *bp;
char buf[10];
if (opt_d) {
bp = buf;
*bp = 0;
if ((chr >= 0x20) && (chr <= 0x7E))
bp += sprintf(bp," '%c'",chr);
dbgprt("showchr: CHR chr=%2.2X%s\n",chr,buf);
}
linebuf[linelen++] = chr;
linebuf[linelen] = 0;
}
// eoftst -- decide if current line is the last line
int
eoftst(void)
{
static char *eofstr = "$GP\n";
static int eoflen = 0;
int stopflg = 0;
if (eoflen == 0)
eoflen = strlen(eofstr);
stopflg = ((linelen == eoflen) && (memcmp(linebuf,eofstr,eoflen) == 0));
dbgprt("eoftst: %s\n",stopflg ? "STOP" : "CONT");
return stopflg;
}
int
main(int argc, char **argv)
{
int timout;
int buf_has_eof = 0;
int curchr;
int err;
int rlen;
int idx;
char buf[1000];
--argc;
++argv;
setlinebuf(stdout);
setlinebuf(stderr);
for (; argc > 0; --argc, ++argv) {
char *cp = *argv;
if (*cp != '-')
break;
cp += 2;
switch (cp[-1]) {
case 'd':
opt_d = ! opt_d;
break;
case 'p':
opt_pty = (*cp != 0) ? cp : "input.txt";
break;
}
}
do {
// create test device
if (opt_pty != NULL) {
dopty();
break;
}
if (argc > 0) {
ttydev = *argv;
--argc;
++argv;
}
} while (0);
dbgprt("main: TTYDEV ttydev=%s\n",ttydev);
fd = open(ttydev, O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror("open_port: Unable to open port\n");
exit(1);
}
#if 0
saio.sa_handler = signal_handler_IO;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO, &saio, NULL);
#endif
// not needed unless doing signal handler
#if 0
fcntl(fd, F_SETFL, FNDELAY);
fcntl(fd, F_SETOWN, getpid());
fcntl(fd, F_SETFL, O_ASYNC);
#endif
#if 1
tcgetattr(fd, &termAttr);
#endif
#if 1
cfsetispeed(&termAttr, B9600);
cfsetospeed(&termAttr, B9600);
#endif
// force immediate return from device read if no chars available
#if 1
dbgprt("main: CC VMIN=%d VTIME=%d\n",
termAttr.c_cc[VMIN],termAttr.c_cc[VTIME]);
termAttr.c_cc[VMIN] = 0;
termAttr.c_cc[VTIME] = 0;
#endif
termAttr.c_cflag &= ~PARENB;
termAttr.c_cflag &= ~CSTOPB;
termAttr.c_cflag &= ~CSIZE;
termAttr.c_cflag |= CS8;
termAttr.c_cflag |= (CLOCAL | CREAD);
// FIXME -- you may need to handle this
#if 1
termAttr.c_cflag &= ~CRTSCTS;
#else
termAttr.c_cflag |= CRTSCTS;
#endif
termAttr.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
termAttr.c_iflag &= ~(IXON | IXOFF | IXANY);
termAttr.c_oflag &= ~OPOST;
#if 1
tcsetattr(fd, TCSANOW, &termAttr);
#endif
printf("UART1 configured....\n");
// open output file
fout = fopen("csvfile.csv","w");
if (fout == NULL) {
perror("main/fopen");
exit(1);
}
fdpoll.fd = fd;
fdpoll.events = POLLIN;
fdpoll.revents = 0;
// set initial timeout of 10 seconds
timout = 10000;
// NOTE: iter is just for testing to prevent infinite looping if failure to
// read or match the EOF string
for (int iter = 1; iter < 10; ++iter) {
dbgprt("main: POLL iter=%d events=%s timout=%d\n",
iter,showpoll(fdpoll.events),timout);
err = poll(&fdpoll,1,timout);
dbgprt("main: POLL revents=%s err=%d\n",showpoll(fdpoll.revents),err);
// timeout
if (err == 0)
break;
// error
if (err < 0) {
fprintf(stderr,"error -- %s\n",strerror(errno));
break;
}
// err will always be _one_ because poll's second arg is 1
// process all data in current chunk
while (1) {
rlen = read(fd,buf,sizeof(buf));
dbgprt("main: READ iter=%d rlen=%d\n",iter,rlen);
if (rlen <= 0)
break;
// send data to output file
#if RAWOUT
fwrite(buf,1,rlen,fout);
#endif
// need to check buf looking for last line (e.g. $GP)
// to know when to stop
// since read is _not_ line oriented we have to check for G followed
// by P [and they may or may not occur in the same read call]
// FIXME -- this is quite crude -- just to illustrate
for (idx = 0; idx < rlen; ++idx) {
curchr = buf[idx];
// add to line buffer
lineadd(curchr);
// wait for newline
if (curchr != '\n')
continue;
// decide if this is the last line of the current NMEA message
buf_has_eof = eoftst();
#if (! RAWOUT)
// do processing on line buffer ...
#endif
// reset line buffer index/length for next line
linelen = 0;
if (buf_has_eof)
break;
}
if (buf_has_eof)
break;
}
if (buf_has_eof)
break;
// set 1 second timeout for subsequent reads
timout = 1000;
#if 0
sleep(1);
#endif
}
close(fd);
fclose(fout);
// reap any child processes [only if doing PTY mode]
while (opt_pty != NULL) {
pid_t pid = wait(NULL);
dbgprt("main: WAIT pid=%d\n",pid);
if (pid <= 0)
break;
}
exit(0);
}
void
signal_handler_IO()
{
FILE *csv;
FILE *ff;
char buff[1024];
ff = fopen("/dev/ttyUSB0", "r");
// int n = read(fd, &buff, sizeof(buff));
fgets(buff, sizeof(buff), ff);
char *token = strtok(buff, ",");
csv = fopen("csvfile.csv", "w");
while (token != NULL) {
fprintf(csv, "%s\n", token);
token = strtok(NULL, ",");
}
sleep(0.2);
fclose(csv);
}