如何通过带有 c 的串行端口从带有 NMEA 协议的 GPS 模块获取数据 [英] How can I get data from a GPS module coming with NMEA protocol through a Serial port with c
问题描述
我需要通过串行端口从采用 NMEA 协议的 GPS 模块获取数据，输入如下所示:
I need to get data from a GPS module which is coming in NMEA protocol through a Serial port, and the input looks something like this:
$GPRMC,190335.389,V,3754.931,N,08002.496,W,33.6,0.59,110619,,E*47$GPGGA,190336.389,3754.931,N,08002.496,W,0,00,,,M,,M,,*52$GPGLL,3754.931,N,08002.496,W,190337.389,V*33$GPVTG,0.59,T,,M,33.6,N,62.2,K*5C$GPRMC,190339.389,V,3754.932,N,08002.494,W,11.9,0.62,110619,,E*4D$GPGGA,190340.389,3754.932,N,08002.494,W,0,00,,,M,,M,,*52$GPGLL,3754.932,N,08002.494,W,190341.389,V*33
$GPRMC,190335.389,V,3754.931,N,08002.496,W,33.6,0.59,110619,,E*47 $GPGGA,190336.389,3754.931,N,08002.496,W,0,00,,,M,,M,,*52 $GPGLL,3754.931,N,08002.496,W,190337.389,V*33 $GPVTG,0.59,T,,M,33.6,N,62.2,K*5C $GPRMC,190339.389,V,3754.932,N,08002.494,W,11.9,0.62,110619,,E*4D $GPGGA,190340.389,3754.932,N,08002.494,W,0,00,,,M,,M,,*52 $GPGLL,3754.932,N,08002.494,W,190341.389,V*33
问题是，我只需要以 GPRMC 开头的行.问题是数据是异步的，例如，首先是一行的前半部分，然后是另一半和另一行的一些，依此类推.现在我怎样才能逐行获取输入并且只获取以 GPRMC 开头的输入.输入不断，我需要实时获得正确的线路.我怎么能用C做到这一点?
The thing is, I only need the lines starting with GPRMC. And the problem is the data is coming asynchronous, first comes the first half of a line, for example, then the other half and some of the other line and so on. Now how can I get the input line-by-line and only get the ones starting with GPRMC. The input is coming incessant and I need to get the correct line real-time. How could I do this with C?
我真的不知道如何从串行端口读取，我尝试了一些方法，但由于输入是异步的，我无法获得正确的行.哦，还有一件事，一行的最大长度是 83.
I don't really know how to read from a Serial port, I tried something but because the input's coming asynchronous, I couldn't get the correct lines. Oh, and one more thing, the maximum length of a line is 83.
这是我试过的一些代码，我知道它很糟糕
Here's some code I tried, I know it's bad
int a = 0;
int test = 0;
int gprmc_find(char* gps)
{
while(a < strlen(gps))
{
if(gps[a] =='$' && gps[a+1] == 'G' && gps[a+2] == 'P' && gps[a+3] == 'R' )
{
test = 1;
break;
}
else
{
test = 0;
}
a++;
return test;
}
}
int main()
{
DWORD accessdirection =GENERIC_READ | GENERIC_WRITE;
HANDLE hSerial = CreateFile("COM4",
accessdirection,
0,
0,
OPEN_EXISTING,
0,
0);
if (hSerial == INVALID_HANDLE_VALUE) {
printf("Invalid\n");
}
DCB dcbSerialParams = {0};
dcbSerialParams.DCBlength=sizeof(dcbSerialParams);
if (!GetCommState(hSerial, &dcbSerialParams)) {
printf("could not get the state of the comport\n");
}
dcbSerialParams.BaudRate=9600;
dcbSerialParams.ByteSize=8;
dcbSerialParams.StopBits=ONESTOPBIT;
dcbSerialParams.Parity=NOPARITY;
if(!SetCommState(hSerial, &dcbSerialParams)){
printf("Error\n");
}
COMMTIMEOUTS timeouts={0};
timeouts.ReadIntervalTimeout=50;
timeouts.ReadTotalTimeoutConstant=50;
timeouts.ReadTotalTimeoutMultiplier=10;
timeouts.WriteTotalTimeoutConstant=50;
timeouts.WriteTotalTimeoutMultiplier=10;
if(!SetCommTimeouts(hSerial, &timeouts)){
printf("handle error1");
}
char buf[83] = {0};
while(1)
{
DWORD dwBytesRead = 0;
//CloseHandle(hSerial);
if(!ReadFile(hSerial, buf, 82, &dwBytesRead, NULL)){
printf("handle error");
}
printf(" %d \n", test);
if(gprmc_find(buf) == 1)
{
printf(buf);
}
memset(buf, 0, 83);
delay(1);
}
return 0;
}
推荐答案
GPS NMEA 0183是一种基于文本的协议，可以使用独立于平台的 C 语言标准库进行处理.
已经开发了许多库和解析器，您无需重新开发即可使用它们.
GPS NMEA 0183 is a text-based protocol and can be processed with a platform-independent C language standard library.
Many libraries and parsers have already been developed, and you can use them without redevelopment.
例如，您可以在 StackOverflow 站点上找到这篇文章:
NMEA 库 - nmeaINFO 为空/NMEA 库
linux串口的C GPS nmea解析器没有解析读缓冲区的最后一行
GPS NMEA 字符串的解析代码
For example, you can find this article on the StackOverflow site:
NMEA library - nmeaINFO empty / NMEA Library
C Gps nmea parser from linux serial port does not parse the last line of the read buffer
Parsing code for GPS NMEA string
其他网站:
使用 BOOST 的多平台串行接口:GPS 传感器和 OPENDDS - 第 I 部分/第二部分
这些是解析器，解析读取数据的库.
jacketizer/libnmea
kosma/minmea
MaJerle/GPS_NMEA_parser
These are parsers, libraries that parse the read data.
jacketizer/libnmea
kosma/minmea
MaJerle/GPS_NMEA_parser
在上述库中分析后，您应该只使用您想要的数据.
After analyzing in the above library, you should use only the data you want.
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