Jordan Beason / GPSINT

Happy Turkey Day

GPSINT.cpp@0:f14093b3b3cf, 2019-11-28 (annotated)

Committer:
jbeason3
Date:
Thu Nov 28 01:38:50 2019 +0000
Revision:
0:f14093b3b3cf
Happy Turkey Day

Who changed what in which revision?

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jbeason3 0:f14093b3b3cf 1 /* GPSINT.cpp
jbeason3 0:f14093b3b3cf 2 * Original program from
jbeason3 0:f14093b3b3cf 3 * jbradshaw (20141101)
jbeason3 0:f14093b3b3cf 4 * The program is modified for ublox NEO 6M.
jbeason3 0:f14093b3b3cf 5 */
jbeason3 0:f14093b3b3cf 6
jbeason3 0:f14093b3b3cf 7 #include "GPSINT.h"
jbeason3 0:f14093b3b3cf 8
jbeason3 0:f14093b3b3cf 9 GPSINT::GPSINT(PinName tx, PinName rx) : _gps(tx, rx) {
jbeason3 0:f14093b3b3cf 10 _gps.baud(9600);
jbeason3 0:f14093b3b3cf 11 GPSidx=0; // Index for GPS buffer
jbeason3 0:f14093b3b3cf 12 GPSstate=0; // Used to wait for '$' in GPS interrupt
jbeason3 0:f14093b3b3cf 13 _gps.attach(this,&GPSINT::GPSSerialRecvInterrupt, _gps.RxIrq); // Recv interrupt handler
jbeason3 0:f14093b3b3cf 14 }
jbeason3 0:f14093b3b3cf 15
jbeason3 0:f14093b3b3cf 16 int GPSINT::nmea_validate(char *nmeastr){
jbeason3 0:f14093b3b3cf 17 char check[3];
jbeason3 0:f14093b3b3cf 18 char checkcalcstr[3];
jbeason3 0:f14093b3b3cf 19 int i;
jbeason3 0:f14093b3b3cf 20 int calculated_check;
jbeason3 0:f14093b3b3cf 21
jbeason3 0:f14093b3b3cf 22 i=0;
jbeason3 0:f14093b3b3cf 23 calculated_check=0;
jbeason3 0:f14093b3b3cf 24
jbeason3 0:f14093b3b3cf 25 // check to ensure that the string starts with a $
jbeason3 0:f14093b3b3cf 26 if(nmeastr[i] == '$')
jbeason3 0:f14093b3b3cf 27 i++;
jbeason3 0:f14093b3b3cf 28 else
jbeason3 0:f14093b3b3cf 29 return 0;
jbeason3 0:f14093b3b3cf 30
jbeason3 0:f14093b3b3cf 31 //No NULL reached, 75 char largest possible NMEA message, no '*' reached
jbeason3 0:f14093b3b3cf 32 while((nmeastr[i] != 0) && (nmeastr[i] != '*') && (i < 75)){
jbeason3 0:f14093b3b3cf 33 calculated_check ^= nmeastr[i];// calculate the checksum
jbeason3 0:f14093b3b3cf 34 i++;
jbeason3 0:f14093b3b3cf 35 }
jbeason3 0:f14093b3b3cf 36
jbeason3 0:f14093b3b3cf 37 if(i >= 75){
jbeason3 0:f14093b3b3cf 38 return 0;// the string was too long so return an error
jbeason3 0:f14093b3b3cf 39 }
jbeason3 0:f14093b3b3cf 40
jbeason3 0:f14093b3b3cf 41 if (nmeastr[i] == '*'){
jbeason3 0:f14093b3b3cf 42 check[0] = nmeastr[i+1]; //put hex chars in check string
jbeason3 0:f14093b3b3cf 43 check[1] = nmeastr[i+2];
jbeason3 0:f14093b3b3cf 44 check[2] = 0;
jbeason3 0:f14093b3b3cf 45 }
jbeason3 0:f14093b3b3cf 46 else
jbeason3 0:f14093b3b3cf 47 return 0;// no checksum separator found therefor invalid
jbeason3 0:f14093b3b3cf 48
jbeason3 0:f14093b3b3cf 49 sprintf(checkcalcstr,"%02X",calculated_check);
jbeason3 0:f14093b3b3cf 50 return((checkcalcstr[0] == check[0])
jbeason3 0:f14093b3b3cf 51 && (checkcalcstr[1] == check[1])) ? 1 : 0 ;
jbeason3 0:f14093b3b3cf 52 }
jbeason3 0:f14093b3b3cf 53
jbeason3 0:f14093b3b3cf 54 void GPSINT::parseGPSString(char *GPSstrParse){
jbeason3 0:f14093b3b3cf 55 //check if $GPGGA string
jbeason3 0:f14093b3b3cf 56 if(!strncmp(GPSstrParse, "$GPGGA", 6)){
jbeason3 0:f14093b3b3cf 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) {
jbeason3 0:f14093b3b3cf 58 // printf("%s", GPSstrParse);
jbeason3 0:f14093b3b3cf 59 return;
jbeason3 0:f14093b3b3cf 60 }
jbeason3 0:f14093b3b3cf 61 else{
jbeason3 0:f14093b3b3cf 62 // printf("BAD parse %s", GPSstrParse);
jbeason3 0:f14093b3b3cf 63 }
jbeason3 0:f14093b3b3cf 64 }
jbeason3 0:f14093b3b3cf 65 // Check if $GPRMC string
jbeason3 0:f14093b3b3cf 66 else if (!strncmp(GPSstrParse, "$GPRMC", 6)){
jbeason3 0:f14093b3b3cf 67 if(sscanf(GPSstrParse, "$GPRMC,%f,%c,%f,%c,%f,%c,%f,%f,%d", &utc_time, &status,&nmea_latitude, &ns, &nmea_longitude, &ew, &speed_k, &course_d, &date) >= 1) {
jbeason3 0:f14093b3b3cf 68 // printf("%s", GPSstrParse);
jbeason3 0:f14093b3b3cf 69 return;
jbeason3 0:f14093b3b3cf 70 }
jbeason3 0:f14093b3b3cf 71 else{
jbeason3 0:f14093b3b3cf 72 // printf("BAD parse %s", GPSstrParse);
jbeason3 0:f14093b3b3cf 73 }
jbeason3 0:f14093b3b3cf 74 }
jbeason3 0:f14093b3b3cf 75 // GLL - Geographic Position-Lat/Lon
jbeason3 0:f14093b3b3cf 76 else if (!strncmp(GPSstrParse, "$GPGLL", 6)){
jbeason3 0:f14093b3b3cf 77 if(sscanf(GPSstrParse, "$GPGLL,%f,%c,%f,%c,%f,%c", &nmea_latitude, &ns, &nmea_longitude, &ew, &utc_time, &gll_status) >= 1) {
jbeason3 0:f14093b3b3cf 78 // printf("%s", GPSstrParse);
jbeason3 0:f14093b3b3cf 79 return;
jbeason3 0:f14093b3b3cf 80 }
jbeason3 0:f14093b3b3cf 81 else{
jbeason3 0:f14093b3b3cf 82 // printf("BAD parse %s", GPSstrParse);
jbeason3 0:f14093b3b3cf 83 }
jbeason3 0:f14093b3b3cf 84 }
jbeason3 0:f14093b3b3cf 85 // VTG-Course Over Ground and Ground Speed
jbeason3 0:f14093b3b3cf 86 else if (!strncmp(GPSstrParse, "$GPVTG", 6)){
jbeason3 0:f14093b3b3cf 87 if(sscanf(GPSstrParse, "$GPVTG,%f,%c,%f,%c,%f,%c,%f,%c", &course_t, &course_t_unit, &course_m, &course_m_unit, &speed_k, &speed_k_unit, &speed_km, &speed_km_unit) >= 1) {
jbeason3 0:f14093b3b3cf 88 // printf("%s", GPSstrParse);
jbeason3 0:f14093b3b3cf 89 return;
jbeason3 0:f14093b3b3cf 90 }
jbeason3 0:f14093b3b3cf 91 else{
jbeason3 0:f14093b3b3cf 92 // printf("BAD parse %s", GPSstrParse);
jbeason3 0:f14093b3b3cf 93 }
jbeason3 0:f14093b3b3cf 94 }
jbeason3 0:f14093b3b3cf 95 }//parseGPSstring()
jbeason3 0:f14093b3b3cf 96
jbeason3 0:f14093b3b3cf 97 void GPSINT::GPSSerialRecvInterrupt(void)
jbeason3 0:f14093b3b3cf 98 {
jbeason3 0:f14093b3b3cf 99 char c;
jbeason3 0:f14093b3b3cf 100 c =_gps.getc(); // On receive interrupt, get the character.
jbeason3 0:f14093b3b3cf 101 // pc.printf("%c", c);
jbeason3 0:f14093b3b3cf 102
jbeason3 0:f14093b3b3cf 103 switch(GPSstate){
jbeason3 0:f14093b3b3cf 104 case 0:
jbeason3 0:f14093b3b3cf 105 if(c =='$'){
jbeason3 0:f14093b3b3cf 106 GPSidx=0;
jbeason3 0:f14093b3b3cf 107 Temp_GPSbuf[GPSidx] = c; //load char in current idx of array
jbeason3 0:f14093b3b3cf 108 GPSidx++;
jbeason3 0:f14093b3b3cf 109 GPSstate = 1;
jbeason3 0:f14093b3b3cf 110 }
jbeason3 0:f14093b3b3cf 111 break;
jbeason3 0:f14093b3b3cf 112 case 1:
jbeason3 0:f14093b3b3cf 113 Temp_GPSbuf[GPSidx] = c; //load char in current idx of array
jbeason3 0:f14093b3b3cf 114 GPSidx++;
jbeason3 0:f14093b3b3cf 115 if(c == '\n'){ //if last char was a newline
jbeason3 0:f14093b3b3cf 116 Temp_GPSbuf[GPSidx] = '\0'; //append a NULL
jbeason3 0:f14093b3b3cf 117 strcpy(GPSbuf, Temp_GPSbuf); //copy temp buf into GPS buf
jbeason3 0:f14093b3b3cf 118 GPSidx=0; //reset index
jbeason3 0:f14093b3b3cf 119 GPSstate = 0; //reset GPS state
jbeason3 0:f14093b3b3cf 120 if(nmea_validate(GPSbuf)){
jbeason3 0:f14093b3b3cf 121 parseGPSString(GPSbuf);
jbeason3 0:f14093b3b3cf 122 }
jbeason3 0:f14093b3b3cf 123 }
jbeason3 0:f14093b3b3cf 124 break;
jbeason3 0:f14093b3b3cf 125
jbeason3 0:f14093b3b3cf 126 default:
jbeason3 0:f14093b3b3cf 127 break;
jbeason3 0:f14093b3b3cf 128
jbeason3 0:f14093b3b3cf 129 }//switch state
jbeason3 0:f14093b3b3cf 130 }
jbeason3 0:f14093b3b3cf 131
jbeason3 0:f14093b3b3cf 132 float GPSINT::nmea_to_dec(float deg_coord, char nsew) {
jbeason3 0:f14093b3b3cf 133 int degree = (int)(deg_coord/100);
jbeason3 0:f14093b3b3cf 134 float minutes = deg_coord - degree*100;
jbeason3 0:f14093b3b3cf 135 float dec_deg = minutes / 60;
jbeason3 0:f14093b3b3cf 136 float decimal = degree + dec_deg;
jbeason3 0:f14093b3b3cf 137 if (nsew == 'S' || nsew == 'W') { // return negative
jbeason3 0:f14093b3b3cf 138 decimal *= -1;
jbeason3 0:f14093b3b3cf 139 }
jbeason3 0:f14093b3b3cf 140 return decimal;
jbeason3 0:f14093b3b3cf 141 }
jbeason3 0:f14093b3b3cf 142
jbeason3 0:f14093b3b3cf 143 // NAVIGATION FUNCTIONS ////////////////////////////////////////////////////////////
jbeason3 0:f14093b3b3cf 144 float GPSINT::calc_course_to(float pointLat, float pontLong) {
jbeason3 0:f14093b3b3cf 145 const double d2r = PI / 180.0;
jbeason3 0:f14093b3b3cf 146 const double r2d = 180.0 / PI;
jbeason3 0:f14093b3b3cf 147 double dlat = abs(pointLat - dec_latitude) * d2r;
jbeason3 0:f14093b3b3cf 148 double dlong = abs(pontLong - dec_longitude) * d2r;
jbeason3 0:f14093b3b3cf 149 double y = sin(dlong) * cos(pointLat * d2r);
jbeason3 0:f14093b3b3cf 150 double x = cos(dec_latitude*d2r)*sin(pointLat*d2r) - sin(dec_latitude*d2r)*cos(pointLat*d2r)*cos(dlong);
jbeason3 0:f14093b3b3cf 151 return atan2(y,x)*r2d;
jbeason3 0:f14093b3b3cf 152 }
jbeason3 0:f14093b3b3cf 153
jbeason3 0:f14093b3b3cf 154 /*
jbeason3 0:f14093b3b3cf 155 var y = Math.sin(dLon) * Math.cos(lat2);
jbeason3 0:f14093b3b3cf 156 var x = Math.cos(lat1)*Math.sin(lat2) -
jbeason3 0:f14093b3b3cf 157 Math.sin(lat1)*Math.cos(lat2)*Math.cos(dLon);
jbeason3 0:f14093b3b3cf 158 var brng = Math.atan2(y, x).toDeg();
jbeason3 0:f14093b3b3cf 159 */
jbeason3 0:f14093b3b3cf 160
jbeason3 0:f14093b3b3cf 161 /*
jbeason3 0:f14093b3b3cf 162 The Haversine formula according to Dr. Math.
jbeason3 0:f14093b3b3cf 163 http://mathforum.org/library/drmath/view/51879.html
jbeason3 0:f14093b3b3cf 164
jbeason3 0:f14093b3b3cf 165 dlon = lon2 - lon1
jbeason3 0:f14093b3b3cf 166 dlat = lat2 - lat1
jbeason3 0:f14093b3b3cf 167 a = (sin(dlat/2))^2 + cos(lat1) * cos(lat2) * (sin(dlon/2))^2
jbeason3 0:f14093b3b3cf 168 c = 2 * atan2(sqrt(a), sqrt(1-a))
jbeason3 0:f14093b3b3cf 169 d = R * c
jbeason3 0:f14093b3b3cf 170
jbeason3 0:f14093b3b3cf 171 Where
jbeason3 0:f14093b3b3cf 172 * dlon is the change in longitude
jbeason3 0:f14093b3b3cf 173 * dlat is the change in latitude
jbeason3 0:f14093b3b3cf 174 * c is the great circle distance in Radians.
jbeason3 0:f14093b3b3cf 175 * R is the radius of a spherical Earth.
jbeason3 0:f14093b3b3cf 176 * The locations of the two points in
jbeason3 0:f14093b3b3cf 177 spherical coordinates (longitude and
jbeason3 0:f14093b3b3cf 178 latitude) are lon1,lat1 and lon2, lat2.
jbeason3 0:f14093b3b3cf 179 */
jbeason3 0:f14093b3b3cf 180 double GPSINT::calc_dist_to_mi(float pointLat, float pontLong) {
jbeason3 0:f14093b3b3cf 181 const double d2r = PI / 180.0;
jbeason3 0:f14093b3b3cf 182 double dlat = pointLat - dec_latitude;
jbeason3 0:f14093b3b3cf 183 double dlong = pontLong - dec_longitude;
jbeason3 0:f14093b3b3cf 184 double a = pow(sin(dlat/2.0),2.0) + cos(dec_latitude*d2r) * cos(pointLat*d2r) * pow(sin(dlong/2.0),2.0);
jbeason3 0:f14093b3b3cf 185 double c = 2.0 * asin(sqrt(abs(a)));
jbeason3 0:f14093b3b3cf 186 double d = 63.765 * c;
jbeason3 0:f14093b3b3cf 187
jbeason3 0:f14093b3b3cf 188 return d;
jbeason3 0:f14093b3b3cf 189 }
jbeason3 0:f14093b3b3cf 190
jbeason3 0:f14093b3b3cf 191 double GPSINT::calc_dist_to_ft(float pointLat, float pontLong) {
jbeason3 0:f14093b3b3cf 192 return calc_dist_to_mi(pointLat, pontLong)*5280.0;
jbeason3 0:f14093b3b3cf 193 }
jbeason3 0:f14093b3b3cf 194
jbeason3 0:f14093b3b3cf 195 double GPSINT::calc_dist_to_km(float pointLat, float pontLong) {
jbeason3 0:f14093b3b3cf 196 return calc_dist_to_mi(pointLat, pontLong)*1.609344;
jbeason3 0:f14093b3b3cf 197 }
jbeason3 0:f14093b3b3cf 198
jbeason3 0:f14093b3b3cf 199 double GPSINT::calc_dist_to_m(float pointLat, float pontLong) {
jbeason3 0:f14093b3b3cf 200 return calc_dist_to_mi(pointLat, pontLong)*1609.344;
jbeason3 0:f14093b3b3cf 201 }