nmealib解析-----（6）----sentence

/*
 *
 * NMEA library
 * URL: http://nmea.sourceforge.net
 * Author: Tim ( [email protected])
 * Licence: http://www.gnu.org/licenses/lgpl.html
 * $Id: sentence.h 17 2008-03-11 11:56:11Z xtimor $
 *
 */

/*! \file */

#ifndef __NMEA_SENTENCE_H__
#define __NMEA_SENTENCE_H__

#include "info.h"

#ifdef  __cplusplus
extern "C" {
#endif

/**
 * NMEA packets type which parsed and generated by library

//nmea数据包类型，用于打包和解包
 */
enum nmeaPACKTYPE
{
    GPNON   = 0x0000,   /**< Unknown packet type. */
    GPGGA   = 0x0001,   /**< GGA - Essential fix data which provide 3D location and accuracy data. */
    GPGSA   = 0x0002,   /**< GSA - GPS receiver operating mode, SVs used for navigation, and DOP values. */
    GPGSV   = 0x0004,   /**< GSV - Number of SVs in view, PRN numbers, elevation, azimuth & SNR values. */
    GPRMC   = 0x0008,   /**< RMC - Recommended Minimum Specific GPS/TRANSIT Data. */
    GPVTG   = 0x0010    /**< VTG - Actual track made good and speed over ground. */
};   //打包类型，他们的值为什么是跳跃式的？？？？

/**
 * GGA packet information structure (Global Positioning System Fix Data)
 */
typedef struct _nmeaGPGGA   //都是使用的typedef来对付struct
{
    nmeaTIME utc;       /**< UTC of position (just time) */
 double  lat;        /**< Latitude in NDEG - [degree][min].[sec/60] */
    char    ns;         /**< [N]orth or [S]outh */
 double  lon;        /**< Longitude in NDEG - [degree][min].[sec/60] */
    char    ew;         /**< [E]ast or [W]est */
    int     sig;        /**< GPS quality indicator (0 = Invalid; 1 = Fix; 2 = Differential, 3 = Sensitive) */
 int     satinuse;   /**< Number of satellites in use (not those in view) */
    double  HDOP;       /**< Horizontal dilution of precision */
    double  elv;        /**< Antenna altitude above/below mean sea level (geoid) */
    char    elv_units;  /**< [M]eters (Antenna height unit) */
    double  diff;       /**< Geoidal separation (Diff. between WGS-84 earth ellipsoid and mean sea level. '-' = geoid is below WGS-84 ellipsoid) */
    char    diff_units; /**< [M]eters (Units of geoidal separation) */
    double  dgps_age;   /**< Time in seconds since last DGPS update */
    int     dgps_sid;   /**< DGPS station ID number */

} nmeaGPGGA;

/**
 * GSA packet information structure (Satellite status)
 */
typedef struct _nmeaGPGSA
{
    char    fix_mode;   /**< Mode (M = Manual, forced to operate in 2D or 3D; A = Automatic, 3D/2D) */
    int     fix_type;   /**< Type, used for navigation (1 = Fix not available; 2 = 2D; 3 = 3D) */
    int     sat_prn[NMEA_MAXSAT]; /**< PRNs of satellites used in position fix (null for unused fields) */
    double  PDOP;       /**< Dilution of precision */
    double  HDOP;       /**< Horizontal dilution of precision */
    double  VDOP;       /**< Vertical dilution of precision */

} nmeaGPGSA;

/**
 * GSV packet information structure (Satellites in view)
 */
typedef struct _nmeaGPGSV
{
    int     pack_count; /**< Total number of messages of this type in this cycle */
    int     pack_index; /**< Message number */
    int     sat_count;  /**< Total number of satellites in view */
    nmeaSATELLITE sat_data[NMEA_SATINPACK];

} nmeaGPGSV;

/**
 * RMC packet information structure (Recommended Minimum sentence C)
 */
typedef struct _nmeaGPRMC
{
    nmeaTIME utc;       /**< UTC of position */
    char    status;     /**< Status (A = active or V = void) */
 double  lat;        /**< Latitude in NDEG - [degree][min].[sec/60] */
    char    ns;         /**< [N]orth or [S]outh */
 double  lon;        /**< Longitude in NDEG - [degree][min].[sec/60] */
    char    ew;         /**< [E]ast or [W]est */
    double  speed;      /**< Speed over the ground in knots */
    double  direction;  /**< Track angle in degrees True */
    double  declination; /**< Magnetic variation degrees (Easterly var. subtracts from true course) */
    char    declin_ew;  /**< [E]ast or [W]est */
    char    mode;       /**< Mode indicator of fix type (A = autonomous, D = differential, E = estimated, N = not valid, S = simulator) */

} nmeaGPRMC;

/**
 * VTG packet information structure (Track made good and ground speed)
 */
typedef struct _nmeaGPVTG
{
    double  dir;        /**< True track made good (degrees) */
    char    dir_t;      /**< Fixed text 'T' indicates that track made good is relative to true north */
    double  dec;        /**< Magnetic track made good */
    char    dec_m;      /**< Fixed text 'M' */
    double  spn;        /**< Ground speed, knots */
    char    spn_n;      /**< Fixed text 'N' indicates that speed over ground is in knots */
    double  spk;        /**< Ground speed, kilometers per hour */
    char    spk_k;      /**< Fixed text 'K' indicates that speed over ground is in kilometers/hour */

} nmeaGPVTG;

 

//初始化各种结构，这里一共就五种结构，也就是说这个lib只能识别这五种结构

void nmea_zero_GPGGA(nmeaGPGGA *pack);
void nmea_zero_GPGSA(nmeaGPGSA *pack);
void nmea_zero_GPGSV(nmeaGPGSV *pack);
void nmea_zero_GPRMC(nmeaGPRMC *pack);
void nmea_zero_GPVTG(nmeaGPVTG *pack);

#ifdef  __cplusplus
}
#endif

#endif /* __NMEA_SENTENCE_H__ */

 

 

 

 

 

/*
 *
 * NMEA library
 * URL: http://nmea.sourceforge.net
 * Author: Tim ( [email protected])
 * Licence: http://www.gnu.org/licenses/lgpl.html
 * $Id: sentence.c 17 2008-03-11 11:56:11Z xtimor $
 *
 */

#include "nmea/sentence.h"

#include <string.h>

void nmea_zero_GPGGA(nmeaGPGGA *pack)
{
    memset(pack, 0, sizeof(nmeaGPGGA));
    nmea_time_now(&pack->utc);    //初始值的时间都可以通过这个函数获得
    pack->ns = 'N';
    pack->ew = 'E';
    pack->elv_units = 'M';
    pack->diff_units = 'M';
}

void nmea_zero_GPGSA(nmeaGPGSA *pack)
{
    memset(pack, 0, sizeof(nmeaGPGSA));
    pack->fix_mode = 'A';
    pack->fix_type = NMEA_FIX_BAD;
}

void nmea_zero_GPGSV(nmeaGPGSV *pack)
{
    memset(pack, 0, sizeof(nmeaGPGSV));
}

void nmea_zero_GPRMC(nmeaGPRMC *pack)
{
    memset(pack, 0, sizeof(nmeaGPRMC));
    nmea_time_now(&pack->utc);
    pack->status = 'V';
    pack->ns = 'N';
    pack->ew = 'E';
    pack->declin_ew = 'E';
}

void nmea_zero_GPVTG(nmeaGPVTG *pack)
{
    memset(pack, 0, sizeof(nmeaGPVTG));
    pack->dir_t = 'T';
    pack->dec_m = 'M';
    pack->spn_n = 'N';
    pack->spk_k = 'K';
}