Mark Schwarzer / GPSINT

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

GPSINT.cpp@0:549c4aa291d5, 2020-11-17 (annotated)

Committer:
markschwarzer
Date:
Tue Nov 17 20:28:54 2020 +0000
Revision:
0:549c4aa291d5
logs gps data to SD card

Who changed what in which revision?

UserRevisionLine numberNew contents of line
markschwarzer 0:549c4aa291d5 1 /* GPSINT.cpp
markschwarzer 0:549c4aa291d5 2 * Original program from
markschwarzer 0:549c4aa291d5 3 * jbradshaw (20141101)
markschwarzer 0:549c4aa291d5 4 * The program is modified for ublox NEO 6M.
markschwarzer 0:549c4aa291d5 5 */
markschwarzer 0:549c4aa291d5 6
markschwarzer 0:549c4aa291d5 7 #include "GPSINT.h"
markschwarzer 0:549c4aa291d5 8
markschwarzer 0:549c4aa291d5 9 GPSINT::GPSINT(PinName tx, PinName rx) : _gps(tx, rx) {
markschwarzer 0:549c4aa291d5 10 _gps.baud(9600);
markschwarzer 0:549c4aa291d5 11 GPSidx=0; // Index for GPS buffer
markschwarzer 0:549c4aa291d5 12 GPSstate=0; // Used to wait for '$' in GPS interrupt
markschwarzer 0:549c4aa291d5 13 _gps.attach(this,&GPSINT::GPSSerialRecvInterrupt, _gps.RxIrq); // Recv interrupt handler
markschwarzer 0:549c4aa291d5 14 }
markschwarzer 0:549c4aa291d5 15
markschwarzer 0:549c4aa291d5 16 int GPSINT::nmea_validate(char *nmeastr){
markschwarzer 0:549c4aa291d5 17 char check[3];
markschwarzer 0:549c4aa291d5 18 char checkcalcstr[3];
markschwarzer 0:549c4aa291d5 19 int i;
markschwarzer 0:549c4aa291d5 20 int calculated_check;
markschwarzer 0:549c4aa291d5 21
markschwarzer 0:549c4aa291d5 22 i=0;
markschwarzer 0:549c4aa291d5 23 calculated_check=0;
markschwarzer 0:549c4aa291d5 24
markschwarzer 0:549c4aa291d5 25 // check to ensure that the string starts with a $
markschwarzer 0:549c4aa291d5 26 if(nmeastr[i] == '$')
markschwarzer 0:549c4aa291d5 27 i++;
markschwarzer 0:549c4aa291d5 28 else
markschwarzer 0:549c4aa291d5 29 return 0;
markschwarzer 0:549c4aa291d5 30
markschwarzer 0:549c4aa291d5 31 //No NULL reached, 75 char largest possible NMEA message, no '*' reached
markschwarzer 0:549c4aa291d5 32 while((nmeastr[i] != 0) && (nmeastr[i] != '*') && (i < 75)){
markschwarzer 0:549c4aa291d5 33 calculated_check ^= nmeastr[i];// calculate the checksum
markschwarzer 0:549c4aa291d5 34 i++;
markschwarzer 0:549c4aa291d5 35 }
markschwarzer 0:549c4aa291d5 36
markschwarzer 0:549c4aa291d5 37 if(i >= 75){
markschwarzer 0:549c4aa291d5 38 return 0;// the string was too long so return an error
markschwarzer 0:549c4aa291d5 39 }
markschwarzer 0:549c4aa291d5 40
markschwarzer 0:549c4aa291d5 41 if (nmeastr[i] == '*'){
markschwarzer 0:549c4aa291d5 42 check[0] = nmeastr[i+1]; //put hex chars in check string
markschwarzer 0:549c4aa291d5 43 check[1] = nmeastr[i+2];
markschwarzer 0:549c4aa291d5 44 check[2] = 0;
markschwarzer 0:549c4aa291d5 45 }
markschwarzer 0:549c4aa291d5 46 else
markschwarzer 0:549c4aa291d5 47 return 0;// no checksum separator found therefor invalid
markschwarzer 0:549c4aa291d5 48
markschwarzer 0:549c4aa291d5 49 sprintf(checkcalcstr,"%02X",calculated_check);
markschwarzer 0:549c4aa291d5 50 return((checkcalcstr[0] == check[0])
markschwarzer 0:549c4aa291d5 51 && (checkcalcstr[1] == check[1])) ? 1 : 0 ;
markschwarzer 0:549c4aa291d5 52 }
markschwarzer 0:549c4aa291d5 53
markschwarzer 0:549c4aa291d5 54 void GPSINT::parseGPSString(char *GPSstrParse){
markschwarzer 0:549c4aa291d5 55 //check if $GPGGA string
markschwarzer 0:549c4aa291d5 56 if(!strncmp(GPSstrParse, "$GPGGA", 6)){
markschwarzer 0:549c4aa291d5 57 if (sscanf(GPSstrParse, "$GPGGA,%f,%f,%c,%f,%c,%d,%d,%f,%f,%c", &utc_time, &nmea_latitude, &ns, &nmea_longitude, &ew, &lock, &satelites, &hdop, &msl_altitude, &msl_units) >= 1) {
markschwarzer 0:549c4aa291d5 58 // printf("%s", GPSstrParse);
markschwarzer 0:549c4aa291d5 59 return;
markschwarzer 0:549c4aa291d5 60 }
markschwarzer 0:549c4aa291d5 61 else{
markschwarzer 0:549c4aa291d5 62 // printf("BAD parse %s", GPSstrParse);
markschwarzer 0:549c4aa291d5 63 }
markschwarzer 0:549c4aa291d5 64 }
markschwarzer 0:549c4aa291d5 65 // Check if $GPRMC string
markschwarzer 0:549c4aa291d5 66 else if (!strncmp(GPSstrParse, "$GPRMC", 6)){
markschwarzer 0:549c4aa291d5 67 if(sscanf(GPSstrParse, "$GPRMC,%f,%c,%f,%c,%f,%c,%f,%f,%d", &utc_time, &status,&nmea_latitude, &ns, &nmea_longitude, &ew, &speed_k, &course_d, &date) >= 1) {
markschwarzer 0:549c4aa291d5 68 // printf("%s", GPSstrParse);
markschwarzer 0:549c4aa291d5 69 return;
markschwarzer 0:549c4aa291d5 70 }
markschwarzer 0:549c4aa291d5 71 else{
markschwarzer 0:549c4aa291d5 72 // printf("BAD parse %s", GPSstrParse);
markschwarzer 0:549c4aa291d5 73 }
markschwarzer 0:549c4aa291d5 74 }
markschwarzer 0:549c4aa291d5 75 // GLL - Geographic Position-Lat/Lon
markschwarzer 0:549c4aa291d5 76 else if (!strncmp(GPSstrParse, "$GPGLL", 6)){
markschwarzer 0:549c4aa291d5 77 if(sscanf(GPSstrParse, "$GPGLL,%f,%c,%f,%c,%f,%c", &nmea_latitude, &ns, &nmea_longitude, &ew, &utc_time, &gll_status) >= 1) {
markschwarzer 0:549c4aa291d5 78 // printf("%s", GPSstrParse);
markschwarzer 0:549c4aa291d5 79 return;
markschwarzer 0:549c4aa291d5 80 }
markschwarzer 0:549c4aa291d5 81 else{
markschwarzer 0:549c4aa291d5 82 // printf("BAD parse %s", GPSstrParse);
markschwarzer 0:549c4aa291d5 83 }
markschwarzer 0:549c4aa291d5 84 }
markschwarzer 0:549c4aa291d5 85 // VTG-Course Over Ground and Ground Speed
markschwarzer 0:549c4aa291d5 86 else if (!strncmp(GPSstrParse, "$GPVTG", 6)){
markschwarzer 0:549c4aa291d5 87 if(sscanf(GPSstrParse, "$GPVTG,%f,%c,%f,%c,%f,%c,%f,%c", &course_t, &course_t_unit, &course_m, &course_m_unit, &speed_k, &speed_k_unit, &speed_km, &speed_km_unit) >= 1) {
markschwarzer 0:549c4aa291d5 88 // printf("%s", GPSstrParse);
markschwarzer 0:549c4aa291d5 89 return;
markschwarzer 0:549c4aa291d5 90 }
markschwarzer 0:549c4aa291d5 91 else{
markschwarzer 0:549c4aa291d5 92 // printf("BAD parse %s", GPSstrParse);
markschwarzer 0:549c4aa291d5 93 }
markschwarzer 0:549c4aa291d5 94 }
markschwarzer 0:549c4aa291d5 95 }//parseGPSstring()
markschwarzer 0:549c4aa291d5 96
markschwarzer 0:549c4aa291d5 97 void GPSINT::GPSSerialRecvInterrupt(void)
markschwarzer 0:549c4aa291d5 98 {
markschwarzer 0:549c4aa291d5 99 char c;
markschwarzer 0:549c4aa291d5 100 c =_gps.getc(); // On receive interrupt, get the character.
markschwarzer 0:549c4aa291d5 101 // pc.printf("%c", c);
markschwarzer 0:549c4aa291d5 102
markschwarzer 0:549c4aa291d5 103 switch(GPSstate){
markschwarzer 0:549c4aa291d5 104 case 0:
markschwarzer 0:549c4aa291d5 105 if(c =='$'){
markschwarzer 0:549c4aa291d5 106 GPSidx=0;
markschwarzer 0:549c4aa291d5 107 Temp_GPSbuf[GPSidx] = c; //load char in current idx of array
markschwarzer 0:549c4aa291d5 108 GPSidx++;
markschwarzer 0:549c4aa291d5 109 GPSstate = 1;
markschwarzer 0:549c4aa291d5 110 }
markschwarzer 0:549c4aa291d5 111 break;
markschwarzer 0:549c4aa291d5 112 case 1:
markschwarzer 0:549c4aa291d5 113 Temp_GPSbuf[GPSidx] = c; //load char in current idx of array
markschwarzer 0:549c4aa291d5 114 GPSidx++;
markschwarzer 0:549c4aa291d5 115 if(c == '\n'){ //if last char was a newline
markschwarzer 0:549c4aa291d5 116 Temp_GPSbuf[GPSidx] = '\0'; //append a NULL
markschwarzer 0:549c4aa291d5 117 strcpy(GPSbuf, Temp_GPSbuf); //copy temp buf into GPS buf
markschwarzer 0:549c4aa291d5 118 GPSidx=0; //reset index
markschwarzer 0:549c4aa291d5 119 GPSstate = 0; //reset GPS state
markschwarzer 0:549c4aa291d5 120 if(nmea_validate(GPSbuf)){
markschwarzer 0:549c4aa291d5 121 parseGPSString(GPSbuf);
markschwarzer 0:549c4aa291d5 122 }
markschwarzer 0:549c4aa291d5 123 }
markschwarzer 0:549c4aa291d5 124 break;
markschwarzer 0:549c4aa291d5 125
markschwarzer 0:549c4aa291d5 126 default:
markschwarzer 0:549c4aa291d5 127 break;
markschwarzer 0:549c4aa291d5 128
markschwarzer 0:549c4aa291d5 129 }//switch state
markschwarzer 0:549c4aa291d5 130 }
markschwarzer 0:549c4aa291d5 131
markschwarzer 0:549c4aa291d5 132 float GPSINT::nmea_to_dec(float deg_coord, char nsew) {
markschwarzer 0:549c4aa291d5 133 int degree = (int)(deg_coord/100);
markschwarzer 0:549c4aa291d5 134 float minutes = deg_coord - degree*100;
markschwarzer 0:549c4aa291d5 135 float dec_deg = minutes / 60;
markschwarzer 0:549c4aa291d5 136 float decimal = degree + dec_deg;
markschwarzer 0:549c4aa291d5 137 if (nsew == 'S' || nsew == 'W') { // return negative
markschwarzer 0:549c4aa291d5 138 decimal *= -1;
markschwarzer 0:549c4aa291d5 139 }
markschwarzer 0:549c4aa291d5 140 return decimal;
markschwarzer 0:549c4aa291d5 141 }
markschwarzer 0:549c4aa291d5 142
markschwarzer 0:549c4aa291d5 143 // NAVIGATION FUNCTIONS ////////////////////////////////////////////////////////////
markschwarzer 0:549c4aa291d5 144 float GPSINT::calc_course_to(float pointLat, float pontLong) {
markschwarzer 0:549c4aa291d5 145 const double d2r = PI / 180.0;
markschwarzer 0:549c4aa291d5 146 const double r2d = 180.0 / PI;
markschwarzer 0:549c4aa291d5 147 double dlat = abs(pointLat - dec_latitude) * d2r;
markschwarzer 0:549c4aa291d5 148 double dlong = abs(pontLong - dec_longitude) * d2r;
markschwarzer 0:549c4aa291d5 149 double y = sin(dlong) * cos(pointLat * d2r);
markschwarzer 0:549c4aa291d5 150 double x = cos(dec_latitude*d2r)*sin(pointLat*d2r) - sin(dec_latitude*d2r)*cos(pointLat*d2r)*cos(dlong);
markschwarzer 0:549c4aa291d5 151 return atan2(y,x)*r2d;
markschwarzer 0:549c4aa291d5 152 }
markschwarzer 0:549c4aa291d5 153
markschwarzer 0:549c4aa291d5 154 /*
markschwarzer 0:549c4aa291d5 155 var y = Math.sin(dLon) * Math.cos(lat2);
markschwarzer 0:549c4aa291d5 156 var x = Math.cos(lat1)*Math.sin(lat2) -
markschwarzer 0:549c4aa291d5 157 Math.sin(lat1)*Math.cos(lat2)*Math.cos(dLon);
markschwarzer 0:549c4aa291d5 158 var brng = Math.atan2(y, x).toDeg();
markschwarzer 0:549c4aa291d5 159 */
markschwarzer 0:549c4aa291d5 160
markschwarzer 0:549c4aa291d5 161 /*
markschwarzer 0:549c4aa291d5 162 The Haversine formula according to Dr. Math.
markschwarzer 0:549c4aa291d5 163 http://mathforum.org/library/drmath/view/51879.html
markschwarzer 0:549c4aa291d5 164
markschwarzer 0:549c4aa291d5 165 dlon = lon2 - lon1
markschwarzer 0:549c4aa291d5 166 dlat = lat2 - lat1
markschwarzer 0:549c4aa291d5 167 a = (sin(dlat/2))^2 + cos(lat1) * cos(lat2) * (sin(dlon/2))^2
markschwarzer 0:549c4aa291d5 168 c = 2 * atan2(sqrt(a), sqrt(1-a))
markschwarzer 0:549c4aa291d5 169 d = R * c
markschwarzer 0:549c4aa291d5 170
markschwarzer 0:549c4aa291d5 171 Where
markschwarzer 0:549c4aa291d5 172 * dlon is the change in longitude
markschwarzer 0:549c4aa291d5 173 * dlat is the change in latitude
markschwarzer 0:549c4aa291d5 174 * c is the great circle distance in Radians.
markschwarzer 0:549c4aa291d5 175 * R is the radius of a spherical Earth.
markschwarzer 0:549c4aa291d5 176 * The locations of the two points in
markschwarzer 0:549c4aa291d5 177 spherical coordinates (longitude and
markschwarzer 0:549c4aa291d5 178 latitude) are lon1,lat1 and lon2, lat2.
markschwarzer 0:549c4aa291d5 179 */
markschwarzer 0:549c4aa291d5 180 double GPSINT::calc_dist_to_mi(float pointLat, float pontLong) {
markschwarzer 0:549c4aa291d5 181 const double d2r = PI / 180.0;
markschwarzer 0:549c4aa291d5 182 double dlat = pointLat - dec_latitude;
markschwarzer 0:549c4aa291d5 183 double dlong = pontLong - dec_longitude;
markschwarzer 0:549c4aa291d5 184 double a = pow(sin(dlat/2.0),2.0) + cos(dec_latitude*d2r) * cos(pointLat*d2r) * pow(sin(dlong/2.0),2.0);
markschwarzer 0:549c4aa291d5 185 double c = 2.0 * asin(sqrt(abs(a)));
markschwarzer 0:549c4aa291d5 186 double d = 63.765 * c;
markschwarzer 0:549c4aa291d5 187
markschwarzer 0:549c4aa291d5 188 return d;
markschwarzer 0:549c4aa291d5 189 }
markschwarzer 0:549c4aa291d5 190
markschwarzer 0:549c4aa291d5 191 double GPSINT::calc_dist_to_ft(float pointLat, float pontLong) {
markschwarzer 0:549c4aa291d5 192 return calc_dist_to_mi(pointLat, pontLong)*5280.0;
markschwarzer 0:549c4aa291d5 193 }
markschwarzer 0:549c4aa291d5 194
markschwarzer 0:549c4aa291d5 195 double GPSINT::calc_dist_to_km(float pointLat, float pontLong) {
markschwarzer 0:549c4aa291d5 196 return calc_dist_to_mi(pointLat, pontLong)*1.609344;
markschwarzer 0:549c4aa291d5 197 }
markschwarzer 0:549c4aa291d5 198
markschwarzer 0:549c4aa291d5 199 double GPSINT::calc_dist_to_m(float pointLat, float pontLong) {
markschwarzer 0:549c4aa291d5 200 return calc_dist_to_mi(pointLat, pontLong)*1609.344;
markschwarzer 0:549c4aa291d5 201 }