MBed_Adafruit_GPS.cpp

00001 /***********************************
00002 This is our GPS library
00003 
00004 Adafruit invests time and resources providing this open source code,
00005 please support Adafruit and open-source hardware by purchasing
00006 products from Adafruit!
00007 
00008 Written by Limor Fried/Ladyada for Adafruit Industries.
00009 BSD license, check license.txt for more information
00010 All text above must be included in any redistribution
00011 ****************************************/
00012 
00013 #include "MBed_Adafruit_GPS.h"
00014 
00015 // how long are max NMEA lines to parse?
00016 #define MAXLINELENGTH 120
00017 
00018 // we double buffer: read one line in and leave one for the main program
00019 volatile char line1[MAXLINELENGTH];
00020 volatile char line2[MAXLINELENGTH];
00021 // our index into filling the current line
00022 volatile uint16_t lineidx=0;
00023 // pointers to the double buffers
00024 volatile char *currentline;
00025 volatile char *lastline;
00026 volatile bool recvdflag;
00027 volatile bool inStandbyMode;
00028 
00029 
00030 bool Adafruit_GPS::parse(char *nmea) {
00031   // do checksum check
00032 
00033   // first look if we even have one
00034   if (nmea[strlen(nmea)-4] == '*') {
00035     uint16_t sum = parseHex(nmea[strlen(nmea)-3]) * 16;
00036     sum += parseHex(nmea[strlen(nmea)-2]);
00037     
00038     // check checksum 
00039     for (uint8_t i=1; i < (strlen(nmea)-4); i++) {
00040       sum ^= nmea[i];
00041     }
00042     if (sum != 0) {
00043       // bad checksum :(
00044       //return false;
00045     }
00046   }
00047 
00048   // look for a few common sentences
00049   if (strstr(nmea, "$GPGGA")) {
00050     // found GGA
00051     char *p = nmea;
00052     // get time
00053     p = strchr(p, ',')+1;
00054     float timef = atof(p);
00055     uint32_t time = timef;
00056     hour = time / 10000;
00057     minute = (time % 10000) / 100;
00058     seconds = (time % 100);
00059 
00060     milliseconds = fmod((double) timef, 1.0) * 1000;
00061 
00062     // parse out latitude
00063     p = strchr(p, ',')+1;
00064     latitude = atof(p);
00065 
00066     p = strchr(p, ',')+1;
00067     if (p[0] == 'N') lat = 'N';
00068     else if (p[0] == 'S') lat = 'S';
00069     else if (p[0] == ',') lat = 0;
00070     else return false;
00071 
00072     // parse out longitude
00073     p = strchr(p, ',')+1;
00074     longitude = atof(p);
00075 
00076     p = strchr(p, ',')+1;
00077     if (p[0] == 'W') lon = 'W';
00078     else if (p[0] == 'E') lon = 'E';
00079     else if (p[0] == ',') lon = 0;
00080     else return false;
00081 
00082     p = strchr(p, ',')+1;
00083     fixquality = atoi(p);
00084 
00085     p = strchr(p, ',')+1;
00086     satellites = atoi(p);
00087 
00088     p = strchr(p, ',')+1;
00089     HDOP = atof(p);
00090 
00091     p = strchr(p, ',')+1;
00092     altitude = atof(p);
00093     p = strchr(p, ',')+1;
00094     p = strchr(p, ',')+1;
00095     geoidheight = atof(p);
00096     return true;
00097   }
00098   if (strstr(nmea, "$GPRMC")) {
00099    // found RMC
00100     char *p = nmea;
00101 
00102     // get time
00103     p = strchr(p, ',')+1;
00104     float timef = atof(p);
00105     uint32_t time = timef;
00106     hour = time / 10000;
00107     minute = (time % 10000) / 100;
00108     seconds = (time % 100);
00109 
00110     milliseconds = fmod((double) timef, 1.0) * 1000;
00111 
00112     p = strchr(p, ',')+1;
00113     // Serial.println(p);
00114     if (p[0] == 'A') 
00115       fix = true;
00116     else if (p[0] == 'V')
00117       fix = false;
00118     else
00119       return false;
00120 
00121     // parse out latitude
00122     p = strchr(p, ',')+1;
00123     latitude = atof(p);
00124 
00125     p = strchr(p, ',')+1;
00126     if (p[0] == 'N') lat = 'N';
00127     else if (p[0] == 'S') lat = 'S';
00128     else if (p[0] == ',') lat = 0;
00129     else return false;
00130 
00131     // parse out longitude
00132     p = strchr(p, ',')+1;
00133     longitude = atof(p);
00134 
00135     p = strchr(p, ',')+1;
00136     if (p[0] == 'W') lon = 'W';
00137     else if (p[0] == 'E') lon = 'E';
00138     else if (p[0] == ',') lon = 0;
00139     else return false;
00140 
00141     // speed
00142     p = strchr(p, ',')+1;
00143     speed = atof(p);
00144 
00145     // angle
00146     p = strchr(p, ',')+1;
00147     angle = atof(p);
00148 
00149     p = strchr(p, ',')+1;
00150     uint32_t fulldate = atof(p);
00151     day = fulldate / 10000;
00152     month = (fulldate % 10000) / 100;
00153     year = (fulldate % 100);
00154 
00155     // we dont parse the remaining, yet!
00156     return true;
00157   }
00158 
00159   return false;
00160 }
00161 
00162 char Adafruit_GPS::read(void) {
00163   char c = 0;
00164   
00165   if (paused) return c;
00166 
00167     if(!gpsSerial->readable()) return c;
00168     c = gpsSerial->getc();
00169 
00170   //print(c);
00171 
00172   if (c == '$') {
00173     currentline[lineidx] = 0;
00174     lineidx = 0;
00175   }
00176   if (c == '\n') {
00177     currentline[lineidx] = 0;
00178 
00179     if (currentline == line1) {
00180       currentline = line2;
00181       lastline = line1;
00182     } else {
00183       currentline = line1;
00184       lastline = line2;
00185     }
00186 
00187     lineidx = 0;
00188     recvdflag = true;
00189   }
00190 
00191   currentline[lineidx++] = c;
00192   if (lineidx >= MAXLINELENGTH)
00193     lineidx = MAXLINELENGTH-1;
00194 
00195   return c;
00196 }
00197 
00198 Adafruit_GPS::Adafruit_GPS (Serial *ser)
00199 {
00200   common_init();     // Set everything to common state, then...
00201   gpsSerial = ser; // ...override gpsSwSerial with value passed.
00202 }
00203 
00204 // Initialization code used by all constructor types
00205 void Adafruit_GPS::common_init(void) {
00206   gpsSerial = NULL;
00207   recvdflag   = false;
00208   paused      = false;
00209   lineidx     = 0;
00210   currentline = line1;
00211   lastline    = line2;
00212 
00213   hour = minute = seconds = year = month = day =
00214     fixquality = satellites = 0; // uint8_t
00215   lat = lon = mag = 0; // char
00216   fix = false; // bool
00217   milliseconds = 0; // uint16_t
00218   latitude = longitude = geoidheight = altitude =
00219     speed = angle = magvariation = HDOP = 0.0; // float
00220 }
00221 
00222 void Adafruit_GPS::begin(int baud)
00223 {
00224   gpsSerial->baud(baud);
00225   wait_ms(10);
00226 }
00227 
00228 void Adafruit_GPS::sendCommand(char *str) {
00229   gpsSerial->printf("%s",str);
00230 }
00231 
00232 bool Adafruit_GPS::newNMEAreceived(void) {
00233   return recvdflag;
00234 }
00235 
00236 void Adafruit_GPS::pause(bool p) {
00237   paused = p;
00238 }
00239 
00240 char *Adafruit_GPS::lastNMEA(void) {
00241   recvdflag = false;
00242   return (char *)lastline;
00243 }
00244 
00245 // read a Hex value and return the decimal equivalent
00246 uint8_t Adafruit_GPS::parseHex(char c) {
00247     if (c < '0')
00248       return 0;
00249     if (c <= '9')
00250       return c - '0';
00251     if (c < 'A')
00252        return 0;
00253     if (c <= 'F')
00254        return (c - 'A')+10;
00255 }
00256 
00257 bool Adafruit_GPS::waitForSentence(char *wait4me, uint8_t max) {
00258   char str[20];
00259 
00260   uint8_t i=0;
00261   while (i < max) {
00262     if (newNMEAreceived()) { 
00263       char *nmea = lastNMEA();
00264       strncpy(str, nmea, 20);
00265       str[19] = 0;
00266       i++;
00267 
00268       if (strstr(str, wait4me))
00269     return true;
00270     }
00271   }
00272 
00273   return false;
00274 }
00275 
00276 bool Adafruit_GPS::LOCUS_StartLogger(void) {
00277   sendCommand(PMTK_LOCUS_STARTLOG);
00278   recvdflag = false;
00279   return waitForSentence(PMTK_LOCUS_LOGSTARTED);
00280 }
00281 
00282 bool Adafruit_GPS::LOCUS_ReadStatus(void) {
00283   sendCommand(PMTK_LOCUS_QUERY_STATUS);
00284   
00285   if (! waitForSentence("$PMTKLOG"))
00286     return false;
00287 
00288   char *response = lastNMEA();
00289   uint16_t parsed[10];
00290   uint8_t i;
00291   
00292   for (i=0; i<10; i++) parsed[i] = -1;
00293   
00294   response = strchr(response, ',');
00295   for (i=0; i<10; i++) {
00296     if (!response || (response[0] == 0) || (response[0] == '*')) 
00297       break;
00298     response++;
00299     parsed[i]=0;
00300     while ((response[0] != ',') && 
00301        (response[0] != '*') && (response[0] != 0)) {
00302       parsed[i] *= 10;
00303       char c = response[0];
00304       if (isdigit(c))
00305         parsed[i] += c - '0';
00306       else
00307         parsed[i] = c;
00308       response++;
00309     }
00310   }
00311   LOCUS_serial = parsed[0];
00312   LOCUS_type = parsed[1];
00313   if (isalpha(parsed[2])) {
00314     parsed[2] = parsed[2] - 'a' + 10; 
00315   }
00316   LOCUS_mode = parsed[2];
00317   LOCUS_config = parsed[3];
00318   LOCUS_interval = parsed[4];
00319   LOCUS_distance = parsed[5];
00320   LOCUS_speed = parsed[6];
00321   LOCUS_status = !parsed[7];
00322   LOCUS_records = parsed[8];
00323   LOCUS_percent = parsed[9];
00324 
00325   return true;
00326 }
00327 
00328 // Standby Mode Switches
00329 bool Adafruit_GPS::standby(void) {
00330   if (inStandbyMode) {
00331     return false;  // Returns false if already in standby mode, so that you do not wake it up by sending commands to GPS
00332   }
00333   else {
00334     inStandbyMode = true;
00335     sendCommand(PMTK_STANDBY);
00336     //return waitForSentence(PMTK_STANDBY_SUCCESS);  // don't seem to be fast enough to catch the message, or something else just is not working
00337     return true;
00338   }
00339 }
00340 
00341 bool Adafruit_GPS::wakeup(void) {
00342   if (inStandbyMode) {
00343    inStandbyMode = false;
00344     sendCommand("");  // send byte to wake it up
00345     return waitForSentence(PMTK_AWAKE);
00346   }
00347   else {
00348       return false;  // Returns false if not in standby mode, nothing to wakeup
00349   }
00350 }
00351 
00352 bool Adafruit_GPS::hasFix(void)
00353 {
00354     return fix;    
00355 
00356 }