The code for the Flora GPS Jacket is pretty simple and straightforward.  We are using the standard Adafruit GPS Library, and the NeoPixel Library. In modern Arduino IDE versions, go to the Arduino Library Manager and select the following libraries to load:

  • Adafruit GPS Library
  • Adafruit NeoPixel Library.

If you are using versions of the IDE older than 1.5, links to the code for the libraries are below. Click the buttons below to download.

Follow the Flora Sewable NeoPixel tutorial for more information about installing the library. Test out the pixel sample code to be sure your pixels are functioning properly.

Next follow the Flora GPS tutorial to test out your GPS module. To make sure your GPS has a direct view of the sky, dip your jacket out the window (but don't let it fall out!). I used a USB extension cable so I could have the jacket out the window but still plugged in to the computer!

If both your pixels and your GPS module are working perfectly in your jacket circuit, head to GitHub to download the Flora GPS Jacket code or grab the code directly from this page:

// Flora GPS + LED Pixel Code
// 
// This code shows how to listen to the GPS module in an interrupt
// which allows the program to have more 'freedom' - just parse
// when a new NMEA sentence is available! Then access data when
// desired.
// 
// Tested and works great with the Adafruit Flora GPS module
//    ------> http://adafruit.com/products/1059
// Pick one up today at the Adafruit electronics shop 
// and help support open source hardware & software! -ada

#include <Adafruit_GPS.h>
#include <SoftwareSerial.h>
#include "Adafruit_NeoPixel.h"

Adafruit_GPS GPS(&Serial1);

// Set GPSECHO to 'false' to turn off echoing the GPS data to the Serial console
// Set to 'true' if you want to debug and listen to the raw GPS sentences
#define GPSECHO false

// this keeps track of whether we're using the interrupt
// off by default!
boolean usingInterrupt = false;

//--------------------------------------------------|
//                    WAYPOINTS                     |
//--------------------------------------------------|
//Please enter the latitude and longitude of your   |
//desired destination:                              |
  #define GEO_LAT                44.995012
  #define GEO_LON               -93.228967
//--------------------------------------------------|

//--------------------------------------------------|
//                    DISTANCE                      |
//--------------------------------------------------|
//Please enter the distance (in meters) from your   |
//destination that you want your LEDs to light up:  |
  #define DESTINATION_DISTANCE   20
//--------------------------------------------------|


// Navigation location
float targetLat = GEO_LAT;
float targetLon = GEO_LON;

// Trip distance
float tripDistance;

boolean isStarted = false;

// Set the first variable to the NUMBER of pixels. 25 = 25 pixels in a row
// second var is pin
Adafruit_NeoPixel strip = Adafruit_NeoPixel(2, 6, NEO_GRB + NEO_KHZ800);


uint8_t LED_Breathe_Table[]  = {   80,  87,  95, 103, 112, 121, 131, 141, 151, 161, 172, 182, 192, 202, 211, 220,
              228, 236, 242, 247, 251, 254, 255, 255, 254, 251, 247, 242, 236, 228, 220, 211,
              202, 192, 182, 172, 161, 151, 141, 131, 121, 112, 103,  95,  87,  80,  73,  66,
               60,  55,  50,  45,  41,  38,  34,  31,  28,  26,  24,  22,  20,  20,  20,  20,
               20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,
               20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  20,  22,  24,  26,  28,
               31,  34,  38,  41,  45,  50,  55,  60,  66,  73 };


#define BREATHE_TABLE_SIZE (sizeof(LED_Breathe_Table))
#define BREATHE_CYCLE    5000      /*breathe cycle in milliseconds*/
#define BREATHE_UPDATE    (BREATHE_CYCLE / BREATHE_TABLE_SIZE)
uint32_t lastBreatheUpdate = 0;
uint8_t breatheIndex = 0;

void setup()  
{
  // connect at 115200 so we can read the GPS fast enough and echo without dropping chars
  // also spit it out
  Serial.begin(115200);

  // 9600 NMEA is the default baud rate for Adafruit MTK GPS's- some use 4800
  GPS.begin(9600);
  
  // uncomment this line to turn on RMC (recommended minimum) and GGA (fix data) including altitude
  GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCGGA);
  // uncomment this line to turn on only the "minimum recommended" data
  //GPS.sendCommand(PMTK_SET_NMEA_OUTPUT_RMCONLY);
  // For parsing data, we don't suggest using anything but either RMC only or RMC+GGA since
  // the parser doesn't care about other sentences at this time
  
  // Set the update rate
  GPS.sendCommand(PMTK_SET_NMEA_UPDATE_1HZ);   // 1 Hz update rate
  // For the parsing code to work nicely and have time to sort thru the data, and
  // print it out we don't suggest using anything higher than 1 Hz

  delay(1000);
  // Ask for firmware version
  Serial1.println(PMTK_Q_RELEASE);
  
    // Start up the LED strip
  strip.begin();

  // Update the strip, to start they are all 'off'
  strip.show();
}

uint32_t timer = millis();

void loop()                     // run over and over again
{
  // read data from the GPS in the 'main loop'
  char c = GPS.read();
  // if you want to debug, this is a good time to do it!
  if (GPSECHO)
      if (c) Serial.print(c);
  
  // if a sentence is received, we can check the checksum, parse it...
  if (GPS.newNMEAreceived()) {
    // a tricky thing here is if we print the NMEA sentence, or data
    // we end up not listening and catching other sentences! 
    // so be very wary if using OUTPUT_ALLDATA and trytng to print out data
    //Serial.println(GPS.lastNMEA());   // this also sets the newNMEAreceived() flag to false
  
    if (!GPS.parse(GPS.lastNMEA()))   // this also sets the newNMEAreceived() flag to false
      return;  // we can fail to parse a sentence in which case we should just wait for another
  }
  

    if (GPS.fix) {
      //Serial.print("Location: ");
      //Serial.print(GPS.latitude, 2); Serial.print(GPS.lat);
      //Serial.print(", "); 
      //Serial.print(GPS.longitude, 2); Serial.println(GPS.lon);
      
      float fLat = decimalDegrees(GPS.latitude, GPS.lat);
      float fLon = decimalDegrees(GPS.longitude, GPS.lon);
      
      if (!isStarted) {
        isStarted = true;
        tripDistance = (double)calc_dist(fLat, fLon, targetLat, targetLon);
      }
      
      //Uncomment below if you want your Flora to navigate to a certain destination.  Then modify the headingDirection function.
      /*if ((calc_bearing(fLat, fLon, targetLat, targetLon) - GPS.angle) > 0) {
        headingDirection(calc_bearing(fLat, fLon, targetLat, targetLon)-GPS.angle);
       }
      else {
        headingDirection(calc_bearing(fLat, fLon, targetLat, targetLon)-GPS.angle+360);
      }*/
      
      headingDistance((double)calc_dist(fLat, fLon, targetLat, targetLon));
      //Serial.print("Distance Remaining:"); Serial.println((double)calc_dist(fLat, fLon, targetLat, targetLon));
      
    }
  //}
  
}

int calc_bearing(float flat1, float flon1, float flat2, float flon2)
{
  float calc;
  float bear_calc;

  float x = 69.1 * (flat2 - flat1); 
  float y = 69.1 * (flon2 - flon1) * cos(flat1/57.3);

  calc=atan2(y,x);

  bear_calc= degrees(calc);

  if(bear_calc<=1){
    bear_calc=360+bear_calc; 
  }
  return bear_calc;
}

void headingDirection(float heading) 
{
  //Use this part of the code to determine which way you need to go.
  //Remember: this is not the direction you are heading, it is the direction to the destination (north = forward).
  if ((heading > 348.75)||(heading < 11.25)) {
    Serial.println("  N");
    //Serial.println("Forward");
  }
  
  if ((heading >= 11.25)&&(heading < 33.75)) {
    Serial.println("NNE");
    //Serial.println("Go Right");
  }  
  
  if ((heading >= 33.75)&&(heading < 56.25)) {
    Serial.println(" NE");
    //Serial.println("Go Right");
  }
  
  if ((heading >= 56.25)&&(heading < 78.75)) {
    Serial.println("ENE");
    //Serial.println("Go Right");
  }
  
  if ((heading >= 78.75)&&(heading < 101.25)) {
    Serial.println("  E");
    //Serial.println("Go Right");
  }
  
  if ((heading >= 101.25)&&(heading < 123.75)) {
    Serial.println("ESE");
    //Serial.println("Go Right");
  }
  
  if ((heading >= 123.75)&&(heading < 146.25)) {
    Serial.println(" SE");
    //Serial.println("Go Right");
  }
  
  if ((heading >= 146.25)&&(heading < 168.75)) {
    Serial.println("SSE");
    //Serial.println("Go Right");
  }
  
  if ((heading >= 168.75)&&(heading < 191.25)) {
    Serial.println("  S");
    //Serial.println("Turn Around");
  }
  
  if ((heading >= 191.25)&&(heading < 213.75)) {
    Serial.println("SSW");
    //Serial.println("Go Left");
  }
  
  if ((heading >= 213.75)&&(heading < 236.25)) {
    Serial.println(" SW");
    //Serial.println("Go Left");
  }
  
  if ((heading >= 236.25)&&(heading < 258.75)) {
    Serial.println("WSW");
    //Serial.println("Go Left");
  }
  
  if ((heading >= 258.75)&&(heading < 281.25)) {
    Serial.println("  W");
    //Serial.println("Go Left");
  }
  
  if ((heading >= 281.25)&&(heading < 303.75)) {
    Serial.println("WNW");
    //Serial.println("Go Left");
  }
  
  if ((heading >= 303.75)&&(heading < 326.25)) {
    Serial.println(" NW");
    //Serial.println("Go Left");
  }
  
  if ((heading >= 326.25)&&(heading < 348.75)) {
    Serial.println("NWN");
    //Serial.println("Go Left");
  }
}

void headingDistance(float fDist)
{
  //Use this part of the code to determine how far you are away from the destination.
  //The total trip distance (from where you started) is divided into five trip segments.
 Serial.println(fDist);
 if ((fDist >= DESTINATION_DISTANCE)) { // You are now within 5 meters of your destination.
    //Serial.println("Trip Distance: 1");
    //Serial.println("Arrived at destination!");
    int i;
    for (i=0; i < strip.numPixels(); i++) {
      strip.setPixelColor(i, 0, 0, 0);
    }  
    strip.show();   // write all the pixels out
  }


  if ((fDist < DESTINATION_DISTANCE)) { // You are now within 5 meters of your destination.
    //Serial.println("Trip Distance: 0");
    //Serial.println("Arrived at destination!");
    breath();
  }
  
}

unsigned long calc_dist(float flat1, float flon1, float flat2, float flon2)
{
  float dist_calc=0;
  float dist_calc2=0;
  float diflat=0;
  float diflon=0;

  diflat=radians(flat2-flat1);
  flat1=radians(flat1);
  flat2=radians(flat2);
  diflon=radians((flon2)-(flon1));

  dist_calc = (sin(diflat/2.0)*sin(diflat/2.0));
  dist_calc2= cos(flat1);
  dist_calc2*=cos(flat2);
  dist_calc2*=sin(diflon/2.0);
  dist_calc2*=sin(diflon/2.0);
  dist_calc +=dist_calc2;

  dist_calc=(2*atan2(sqrt(dist_calc),sqrt(1.0-dist_calc)));

  dist_calc*=6371000.0; //Converting to meters
  return dist_calc;
}

// Convert NMEA coordinate to decimal degrees
float decimalDegrees(float nmeaCoord, char dir) {
  uint16_t wholeDegrees = 0.01*nmeaCoord;
  int modifier = 1;

  if (dir == 'W' || dir == 'S') {
    modifier = -1;
  }
  
  return (wholeDegrees + (nmeaCoord - 100.0*wholeDegrees)/60.0) * modifier;
}

void breath()
{
  uniformBreathe(LED_Breathe_Table, BREATHE_TABLE_SIZE, BREATHE_UPDATE, 127, 127, 127);
}

void uniformBreathe(uint8_t* breatheTable, uint8_t breatheTableSize, uint16_t updatePeriod, uint16_t r, uint16_t g, uint16_t b)
{
  int i;

  uint8_t breatheBlu;
  
  if ((millis() - lastBreatheUpdate) > updatePeriod) {
    lastBreatheUpdate = millis();

    
    for (i=0; i < strip.numPixels(); i++) {
      breatheBlu = (b * breatheTable[breatheIndex]) / 256;
      strip.setPixelColor(i, 0, 0, breatheBlu);
    }
    strip.show();   
    
    breatheIndex++;
    if (breatheIndex > breatheTableSize) {
      breatheIndex = 0;
    }   
  }
}

Unzip the package and drag the Flora_GPS_Jacket folder into your Arduino folder (located by default in Documents on OS X). Open the enclosed Flora_GPS_Jacket.ino file in the Adafruit Arduino IDE.

The code is easy to modify for your own waypoint and range of sensitivity. Adjust these variables to your own preference. We like GetLatLong.Net for finding latitudes and longitudes online. Upload your customized code to your jacket.

This guide was first published on Jan 09, 2013. It was last updated on Jan 09, 2013.

This page (The Code) was last updated on Nov 27, 2020.