北斗/GPS

北斗/GPS都是用的nmea通用协议。

NMEA-0183协议定义的语句非常多，但是常用的或者说兼容性最广的语句只有$GPGGA、$GPGSA、$GPGSV、$GPRMC、$GPVTG、$GPGLL等。

GPRMC具体细节：

/*
Format

  $GPRMC,123519,A,4807.038,N,01131.000,E,022.4,084.4,230394,003.1,W*6A
     |     |        | |             |             |       |     |        |       |
     |     |        | |             |             |       |     |        |       *6A Checksum data
     |     |        | |             |             |       |     |        |
     |     |        | |             |             |       |     |        003.1,W Magnetic Variation
     |     |        | |             |             |       |     |
     |     |        | |             |             |       |     230394 Date - 23rd of March 1994
     |     |        | |             |             |       |
     |     |        | |             |             |       084.4 Track angle in degrees
     |     |        | |             |             |
     |     |        | |             |             022.4 Speed over the ground in knots
     |     |        | |             |
     |     |        | |             01131.000,E Longitude 11 deg 31.000‘ E
     |     |        | |
     |     |        | 4807.038,N Latitude 48 deg 07.038‘ N
     |     |        |
     |     |        A Status A=active or V=Void
     |     |
     |     123519 Fix taken at 12:35:19 UTC
     |
     RMC Recommended Minimum sentence C

*/

1、NMEA library

开源的NMEA library就够用了，而且至今也没发现有比这个更好的解析库

支持: GPGGA, GPGSA, GPGSV, GPRMC, GPVTG

跨平台，支持如下编译环境

• Microsoft Windows (MS Visual Studio 8.0, GCC)
• Windows Mobile, Windows CE (MS Visual Studio 8.0)
• UNIX (GCC)

http://nmea.sourceforge.net/

有人建了个eclipse工程，这些库建工程很繁琐，偷懒无罪。

https://github.com/AHR-Project/nmealib

2、GPS Library

之前在cortex-m3上调过北斗并且在cortex-m4上调过GPS，也都是在网上找了个现成的解析实例，这种大众化的模块不用重复造轮子了。

Library 27- Read GPS data on STM32F4 devices

Features

• Parse GPS data
• Supported NMEA 0183 standard
• Works with GPGGA, GPRMC, GPGSA, GPGSV NMEA statements
• Version 1.1 – August 22, 2014
  • Calculate distance between 2 coordinates
  • Calculate bearing between 2 coordinates
• Allows you to select custom NMEA statements

http://stm32f4-discovery.com/2014/08/library-27-gps-stm32f4-devices/

完整的库文件和工程在github

https://github.com/MaJerle/stm32f429