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The Citi Bike Helmet code takes the FLORA to the limit. The code is used to drive LEDs, the FLORA GPS module, and the FLORA compass/accelerometer module. It looks at a long list of all Citi bike sharing stations in NYC (over 300!) and determines which coordinate is closest to you. It then uses the GPS module, and the compass module to navigate you there. The code is located in this GitHub repo. Click the button below to download the code.

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// SPDX-FileCopyrightText: 2019 Becky Stern for Adafruit Industries
// SPDX-FileCopyrightText: 2019 Justin Cooper for Adafruit Industries
//
// SPDX-License-Identifier: MIT

// Code for the Adafruit FLora Citi Bike Helmet Tutorial
// https://learn.adafruit.com/citi-bike-helmet
// Becky Stern and Justin Cooper, Adafruit.com
//
// 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
//    ------> https://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 <Wire.h>
#include <LSM303.h>
#include <Adafruit_NeoPixel.h>

LSM303 compass;

#define LAT_LON_SIZE 311

const float lat_lon[LAT_LON_SIZE][2] PROGMEM = {
  {40.767272, -73.993928},
  {40.719115, -74.006666},
  {40.711174, -74.000165},
  {40.683826, -73.976323},
  {40.741776, -74.001497},
  {40.696089, -73.978034},
  {40.686767, -73.959281},
  {40.731724, -74.006744},
  {40.727102, -74.002970},
  {40.714255, -73.981308},
  {40.692395, -73.993379},
  {40.698398, -73.980689},
  {40.716250, -74.009105},
  {40.715421, -74.011219},
  {40.720873, -73.980857},
  {40.721815, -73.997203},
  {40.714739, -74.009106},
  {40.690892, -73.996123},
  {40.729170, -73.998102},
  {40.753230, -73.970325},
  {40.748900, -73.976048},
  {40.739713, -73.994564},
  {40.760646, -73.984426},
  {40.738176, -73.977386},
  {40.709056, -74.010433},
  {40.743349, -74.006817},
  {40.700378, -73.995480},
  {40.702771, -73.993836},
  {40.690284, -73.987071},
  {40.737815, -73.999946},
  {40.711463, -74.005524},
  {40.741951, -74.008030},
  {40.727434, -73.993790},
  {40.695976, -73.990148},
  {40.692462, -73.989639},
  {40.728418, -73.987139},
  {40.730473, -73.986723},
  {40.736196, -74.008592},
  {40.691965, -73.981301},
  {40.689810, -73.974931},
  {40.697883, -73.973503},
  {40.688663, -73.980518},
  {40.691960, -73.965368},
  {40.693270, -73.977038},
  {40.735353, -74.004830},
  {40.721853, -74.007717},
  {40.718709, -74.009000},
  {40.724560, -73.995652},
  {40.723179, -73.994800},
  {40.732263, -73.998522},
  {40.735439, -73.994539},
  {40.735324, -73.998004},
  {40.719392, -74.002472},
  {40.689407, -73.968854},
  {40.701221, -74.012342},
  {40.703651, -74.011677},
  {40.694748, -73.983624},
  {40.691782, -73.973729},
  {40.717290, -73.996375},
  {40.707064, -74.007318},
  {40.722293, -73.991475},
  {40.723683, -73.975748},
  {40.750977, -73.987654},
  {40.719105, -73.999733},
  {40.693082, -73.971789},
  {40.685281, -73.978058},
  {40.686918, -73.976682},
  {40.686500, -73.965633},
  {40.717487, -74.010455},
  {40.697665, -73.984764},
  {40.699869, -73.982719},
  {40.733319, -73.995101},
  {40.708272, -73.968341},
  {40.734545, -73.990741},
  {40.684568, -73.958810},
  {40.760202, -73.964784},
  {40.713452, -73.983985},
  {40.730286, -73.990764},
  {40.730493, -73.995721},
  {40.714066, -73.992939},
  {40.714130, -73.997046},
  {40.686832, -73.979677},
  {40.728984, -73.990518},
  {40.722174, -73.983687},
  {40.720828, -73.977931},
  {40.723627, -73.999496},
  {40.704633, -74.013617},
  {40.760957, -73.967244},
  {40.708235, -74.005300},
  {40.714274, -73.989900},
  {40.713079, -73.998511},
  {40.714978, -74.013012},
  {40.689269, -73.989128},
  {40.717227, -73.988020},
  {40.722632, -73.988873},
  {40.696102, -73.967510},
  {40.694246, -73.992159},
  {40.703553, -74.006702},
  {40.709559, -74.006536},
  {40.724537, -73.981854},
  {40.753201, -73.977987},
  {40.713361, -74.009376},
  {40.717439, -74.005834},
  {40.699917, -73.989717},
  {40.696192, -73.991218},
  {40.692361, -73.986317},
  {40.689888, -73.981013},
  {40.736245, -73.984737},
  {40.729538, -73.984267},
  {40.715337, -74.016583},
  {40.724055, -74.009659},
  {40.720434, -74.010206},
  {40.714504, -74.005627},
  {40.711731, -73.991930},
  {40.712199, -73.979481},
  {40.742387, -73.997262},
  {40.729039, -73.994046},
  {40.730477, -73.999060},
  {40.703799, -74.008386},
  {40.725806, -73.974224},
  {40.712690, -73.987763},
  {40.717821, -73.976289},
  {40.717399, -73.980165},
  {40.697940, -73.969868},
  {40.685144, -73.953809},
  {40.736494, -73.997043},
  {40.736528, -74.006180},
  {40.728738, -74.007488},
  {40.724909, -74.001547},
  {40.718502, -73.983298},
  {40.715595, -73.987029},
  {40.705309, -74.006125},
  {40.763406, -73.977224},
  {40.685395, -73.974314},
  {40.693631, -73.962235},
  {40.716021, -73.999743},
  {40.716226, -73.982612},
  {40.732617, -73.991580},
  {40.732915, -74.007113},
  {40.755102, -73.974986},
  {40.707179, -74.008873},
  {40.716058, -73.991907},
  {40.751726, -73.987535},
  {40.708346, -74.017134},
  {40.689004, -73.960238},
  {40.682231, -73.961458},
  {40.693261, -73.968896},
  {40.758280, -73.970694},
  {40.730385, -74.002149},
  {40.732241, -74.000263},
  {40.694528, -73.958089},
  {40.693317, -73.953819},
  {40.726794, -73.996950},
  {40.708621, -74.007221},
  {40.722437, -74.005664},
  {40.734011, -74.002938},
  {40.734926, -73.992005},
  {40.736251, -74.000836},
  {40.683178, -73.965964},
  {40.714948, -74.002344},
  {40.712732, -74.004607},
  {40.710445, -73.965250},
  {40.692215, -73.984284},
  {40.697601, -73.993445},
  {40.695078, -73.987247},
  {40.722992, -73.979954},
  {40.725213, -73.977687},
  {40.688070, -73.984106},
  {40.680342, -73.955768},
  {40.684157, -73.969222},
  {40.691651, -73.999978},
  {40.688515, -73.964762},
  {40.719260, -73.981780},
  {40.720195, -73.989978},
  {40.740343, -73.989551},
  {40.725028, -73.990696},
  {40.740582, -74.005508},
  {40.739323, -74.008119},
  {40.695128, -73.995950},
  {40.700101, -73.991043},
  {40.710762, -73.994003},
  {40.720664, -73.985179},
  {40.722280, -73.976687},
  {40.715815, -73.994223},
  {40.702818, -73.987657},
  {40.704717, -74.009260},
  {40.687534, -73.972651},
  {40.712912, -74.010202},
  {40.702240, -73.982578},
  {40.695807, -73.973555},
  {40.687644, -73.969689},
  {40.695733, -73.971296},
  {40.770513, -73.988038},
  {40.765849, -73.986905},
  {40.717548, -74.013220},
  {40.702515, -74.014270},
  {40.724677, -73.987834},
  {40.701485, -73.986569},
  {40.688646, -73.982634},
  {40.726217, -73.983798},
  {40.729553, -73.980572},
  {40.743174, -74.003664},
  {40.741739, -73.994155},
  {40.682165, -73.953990},
  {40.680983, -73.950047},
  {40.727791, -73.985649},
  {40.726280, -73.989780},
  {40.752554, -73.972826},
  {40.756019, -73.967446},
  {40.746841, -73.994458},
  {40.708530, -73.964089},
  {40.742354, -73.989150},
  {40.727407, -73.981420},
  {40.744876, -73.995298},
  {40.763707, -73.985161},
  {40.756603, -73.997900},
  {40.764618, -73.987894},
  {40.762272, -73.987882},
  {40.744751, -73.999153},
  {40.754557, -73.965929},
  {40.750019, -73.969053},
  {40.759710, -73.974023},
  {40.766953, -73.981693},
  {40.748061, -74.007231},
  {40.745227, -74.007979},
  {40.712858, -73.965902},
  {40.735876, -73.982050},
  {40.746919, -74.004518},
  {40.742065, -74.004431},
  {40.759345, -73.967596},
  {40.755135, -73.986580},
  {40.743954, -73.991448},
  {40.683124, -73.978951},
  {40.765265, -73.981923},
  {40.763440, -73.982681},
  {40.743453, -74.000040},
  {40.712868, -73.956981},
  {40.745712, -73.981948},
  {40.721100, -73.991925},
  {40.745167, -73.986830},
  {40.735242, -73.987585},
  {40.743943, -73.979660},
  {40.756405, -73.990026},
  {40.760300, -73.998842},
  {40.760192, -73.991255},
  {40.766696, -73.990617},
  {40.712604, -73.962644},
  {40.739355, -73.999317},
  {40.732232, -73.988899},
  {40.755002, -73.980144},
  {40.750380, -73.983389},
  {40.746200, -73.988557},
  {40.733142, -73.975738},
  {40.756458, -73.993722},
  {40.750663, -74.001768},
  {40.751575, -73.994190},
  {40.740963, -73.986022},
  {40.750199, -73.990930},
  {40.756800, -73.982911},
  {40.747348, -73.997235},
  {40.762698, -73.993012},
  {40.737261, -73.992389},
  {40.737049, -73.990092},
  {40.748548, -73.988084},
  {40.762288, -73.983361},
  {40.744219, -73.971212},
  {40.738274, -73.987519},
  {40.732218, -73.981655},
  {40.749012, -73.988483},
  {40.739126, -73.979737},
  {40.763413, -73.996674},
  {40.745497, -74.001971},
  {40.760659, -73.980420},
  {40.729386, -73.977724},
  {40.750072, -73.998392},
  {40.768254, -73.988639},
  {40.760875, -74.002776},
  {40.760094, -73.994618},
  {40.752068, -73.967843},
  {40.751492, -73.977988},
  {40.747803, -73.973441},
  {40.751884, -73.977701},
  {40.759922, -73.976485},
  {40.750449, -73.994810},
  {40.757147, -73.972078},
  {40.754665, -73.991381},
  {40.755273, -73.983169},
  {40.755941, -74.002116},
  {40.747659, -73.984907},
  {40.743155, -73.974347},
  {40.742909, -73.977060},
  {40.757569, -73.990985},
  {40.771522, -73.990541},
  {40.718939, -73.992662},
  {40.710451, -73.960876},
  {40.752996, -73.987216},
  {40.702550, -74.012723},
  {40.741443, -73.975360},
  {40.740258, -73.984092},
  {40.757952, -73.977876},
  {40.715348, -73.960241},
  {40.741472, -73.983209},
  {40.736502, -73.978094},
  {40.744449, -73.983035},
  {40.702550, -73.989402},
  {40.698920, -73.973329},
  {40.716887, -73.963198},
  {40.734160, -73.980242},
  {40.725500, -74.004451},
  {40.705311, -73.971000},
  {40.765909, -73.976341}
};

// Connect the GPS Power pin to 5V
// Connect the GPS Ground pin to ground
// If using software serial (sketch example default):
//   Connect the GPS TX (transmit) pin to Digital 8
//   Connect the GPS RX (receive) pin to Digital 7
// If using hardware serial:
//   Connect the GPS TX (transmit) pin to Arduino RX1 (Digital 0)
//   Connect the GPS RX (receive) pin to matching TX1 (Digital 1)

// If using software serial, keep these lines enabled
// (you can change the pin numbers to match your wiring):
//SoftwareSerial mySerial(8, 7);
//Adafruit_GPS GPS(&mySerial);

// If using hardware serial, comment
// out the above two lines and enable these two lines instead:
Adafruit_GPS GPS(&Serial1);
HardwareSerial mySerial = 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

Adafruit_NeoPixel strip = Adafruit_NeoPixel(45, 6, NEO_GRB + NEO_KHZ800);
int FarRight = 9;
int CenterRight = 10;
int CenterLeft = 34;
int FarLeft = 35;
int HeadsUp[] = {35, 34, 10, 9};
int RightStrip[] = {8, 7, 6, 5, 4, 3, 2, 1, 0};
int RightCenterStrip[] = {11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21};
int LeftCenterStrip[] = {33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23};
int LeftStrip[] = {36, 37, 38, 39, 40, 41, 42, 43, 44};
int counter = 0;

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

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);
  delay(5000);
  
  Serial.println("initialize");
  //test to find the closest location from the list, just plug in a lat lon from the above Array
  //Serial.print("Closest Test Loc: ");
  //Serial.println(find_closest_location(40.726378, -74.005437));

  Wire.begin();
  // 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
  compass.init();
  compass.enableDefault();
  // Calibration values. Use the Calibrate example program to get the values for
  // your compass.
  compass.m_min.x = -581; compass.m_min.y = -731; compass.m_min.z = -1097;
  compass.m_max.x = +615; compass.m_max.y = +470; compass.m_max.z = 505;
  delay(1000);
  // Ask for firmware version
  Serial1.println(PMTK_Q_RELEASE);
  
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
}



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 millis() or timer wraps around, we'll just reset it
  if (timer > millis())  timer = millis();

  // every 300 milliseconds, update the heading/distance indicators
  if (millis() - timer > 300) { 
    timer = millis(); // reset the timer
    
    //Serial.print("\nTime: ");
    //Serial.print(GPS.hour, DEC); Serial.print(':');
    //Serial.print(GPS.minute, DEC); Serial.print(':');
    //Serial.print(GPS.seconds, DEC); Serial.print('.');
    //Serial.println(GPS.milliseconds);
    //Serial.print("Date: ");
    //Serial.print(GPS.day, DEC); Serial.print('/');
    //Serial.print(GPS.month, DEC); Serial.print("/20");
    //Serial.println(GPS.year, DEC);
    //Serial.print("Fix: "); Serial.print((int)GPS.fix);
    //Serial.print(" quality: "); Serial.println((int)GPS.fixquality); 
    if (GPS.fix) {
      Serial.print("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);
      
      int closest_loc = find_closest_location(fLat, fLon);
      float targetLat = pgm_read_float(&lat_lon[closest_loc][0]);
      float targetLon = pgm_read_float(&lat_lon[closest_loc][1]);
      
      //Serial.print("Speed (knots): "); Serial.println(GPS.speed);
      //Serial.print("Angle: "); Serial.println(GPS.angle);
      //Serial.print("Altitude: "); Serial.println(GPS.altitude);
      //Serial.print("Satellites: "); Serial.println((int)GPS.satellites);
      compass.read();
      int heading = compass.heading((LSM303::vector<int16_t>){0,-1,0});
      Serial.print("Heading: ");
      Serial.println(heading);
      if ((calc_bearing(fLat, fLon, targetLat, targetLon) - heading) > 0) {
        headingDirection(calc_bearing(fLat, fLon, targetLat, targetLon)-heading);
       }
      else {
        headingDirection(calc_bearing(fLat, fLon, targetLat, targetLon)-heading+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");
    GoForward(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 11.25)&&(heading < 33.75)) {
    Serial.println("NNE");
    //Serial.println("Go Right");
    TurnRight(strip.Color(16, 247, 206), 200);
  }  
  
  if ((heading >= 33.75)&&(heading < 56.25)) {
    Serial.println(" NE");
    //Serial.println("Go Right");
    TurnRight(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 56.25)&&(heading < 78.75)) {
    Serial.println("ENE");
    //Serial.println("Go Right");
    TurnRight(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 78.75)&&(heading < 101.25)) {
    Serial.println("  E");
    //Serial.println("Go Right");
    TurnRight(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 101.25)&&(heading < 123.75)) {
    Serial.println("ESE");
    //Serial.println("Go Right");
    TurnRight(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 123.75)&&(heading < 146.25)) {
    Serial.println(" SE");
    //Serial.println("Go Right");
    TurnRight(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 146.25)&&(heading < 168.75)) {
    Serial.println("SSE");
    //Serial.println("Go Right");
    TurnRight(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 168.75)&&(heading < 191.25)) {
    Serial.println("  S");
    //Serial.println("Turn Around");
    TurnAround(strip.Color(247, 16, 70), 200);
  }
  
  if ((heading >= 191.25)&&(heading < 213.75)) {
    Serial.println("SSW");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 213.75)&&(heading < 236.25)) {
    Serial.println(" SW");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 236.25)&&(heading < 258.75)) {
    Serial.println("WSW");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 258.75)&&(heading < 281.25)) {
    Serial.println("  W");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 281.25)&&(heading < 303.75)) {
    Serial.println("WNW");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 303.75)&&(heading < 326.25)) {
    Serial.println(" NW");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(16, 247, 206), 200);
  }
  
  if ((heading >= 326.25)&&(heading < 348.75)) {
    Serial.println("NWN");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(16, 247, 206), 200);
  }
}

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;
}

//returns the location in the lat_lon array of the closest lat lon to the current location
int find_closest_location(float current_lat, float current_lon)
{  
  int closest = 0;
  signed long minDistance = -1;
  signed long tempDistance;
  for (int i=0; i < LAT_LON_SIZE; i++) {
    float target_lat = pgm_read_float(&lat_lon[i][0]);
    float target_lon = pgm_read_float(&lat_lon[i][1]);

    tempDistance = calc_dist(current_lat, current_lon, target_lat, target_lon);
    
    /*
    Serial.print("current_lat: ");
    Serial.println(current_lat, 6);
    Serial.print("current_lon: ");
    Serial.println(current_lon, 6); 
    Serial.print("target_lat: ");
    Serial.println(target_lat, 6);
    Serial.print("target_lon: ");
    Serial.println(target_lon, 6);  
    
    Serial.print("tempDistance: ");
    Serial.println(tempDistance);
    Serial.print("Array Loc: ");
    Serial.println(i); 
    */
    
    if ((minDistance > tempDistance) || (minDistance == -1)) {
      minDistance = tempDistance;
      closest = i;

    }
 
  }
  return closest;
}

// 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 TurnLeft (uint32_t c, uint8_t wait) {
  strip.setPixelColor(CenterRight, 0);
  strip.setPixelColor(CenterLeft, 0);
  strip.setPixelColor(FarLeft, c);
      strip.show();
      delay(wait);
  strip.setPixelColor(FarLeft, 0);
  strip.show();
      delay(wait);
}

void TurnRight (uint32_t c, uint8_t wait) {
  strip.setPixelColor(CenterRight, 0);
  strip.setPixelColor(CenterLeft, 0);
  strip.setPixelColor(FarRight, c);
      strip.show();
      delay(wait);
  strip.setPixelColor(FarRight, 0);
  strip.show();
      delay(wait);
}

void TurnAround (uint32_t c, uint8_t wait) {
  strip.setPixelColor(CenterRight, c);
  strip.setPixelColor(CenterLeft, c);
      strip.show();
      delay(wait);
  strip.setPixelColor(CenterRight, 0);
  strip.setPixelColor(CenterLeft, 0);
  strip.show();
      delay(wait);
      
}

void GoForward (uint32_t c, uint8_t wait) {
  strip.setPixelColor(CenterRight, c);
  strip.setPixelColor(CenterLeft, c);
      strip.show();
      
      delay(wait);
}

// Slightly different, this makes the rainbow equally distributed throughout
void rainbowCycle(uint8_t wait) {
  uint16_t i;

  //for(j=0; j<256*5; j++) { // 5 cycles of all colors on wheel
    for(i=0; i< 10; i++) {
      strip.setPixelColor(RightStrip[i], Wheel(((i * 256 / 10) + counter) & 255));
      strip.setPixelColor(RightCenterStrip[i], Wheel(((i * 256 / 10) + counter) & 255));
      strip.setPixelColor(LeftCenterStrip[i], Wheel(((i * 256 / 10) + counter) & 255));
      strip.setPixelColor(LeftStrip[i], Wheel(((i * 256 / 10) + counter) & 255));
    }
    counter = counter+25;
    if (counter >256*5) {counter = 0;}
    strip.show();
    delay(wait);
  //}
}


// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if(WheelPos < 85) {
   return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if(WheelPos < 170) {
   WheelPos -= 85;
   return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
   WheelPos -= 170;
   return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}
View on GitHub
Right near the top of the sketch, you are going to see a long list of GPS coordinates that look like this:
Download File
Copy Code 
float lat_lon[LAT_LON_SIZE][2] PROGMEM = {
  {40.767272, -73.993928},
  {40.719115, -74.006666},
  {40.711174, -74.000165},
These coordinates were copied and pasted using a bit of node.js (learn more here). This also means that if you live in a city other than NYC that has a bike sharing program, you can use our code to get your own list of coordinates. If you live in NYC, all of the current bike share stations are loaded into the sketch.
The next piece of important code is this:
Download File
Copy Code 
// Change the first # to match the # of LEDs in your strip -- we have 45 LEDs
Adafruit_NeoPixel strip = Adafruit_NeoPixel(45, 6, NEO_GRB + NEO_KHZ800);

int FarRight = 9;
int CenterRight = 10;
int CenterLeft = 34;
int FarLeft = 35;
int HeadsUp[] = {35, 34, 10, 9};
int RightStrip[] = {8, 7, 6, 5, 4, 3, 2, 1, 0};
int RightCenterStrip[] = {11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21};
int LeftCenterStrip[] = {33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23};
int LeftStrip[] = {36, 37, 38, 39, 40, 41, 42, 43, 44};
int counter = 0;
This is where we set up which LEDs on our helmet are used. This will likely need to be updated to fit your own bike helmet project. Learn more about how the FLORA NeoPixels work here.

In the setup function, you will find a section that deals with calibrating the FLORA compass module.
Download File
Copy Code 
// Calibration values. Use the Calibrate example program to get the values for
// your compass.
  compass.m_min.x = -581; compass.m_min.y = -731; compass.m_min.z = -1097;
  compass.m_max.x = +615; compass.m_max.y = +470; compass.m_max.z = 505;
Included with the Pololu LSM303 library is a little sketch that will get you these values. Run the sketch and view the serial monitor. Then tilt your helmet/sensor in every possible direction. When done, dump the values in the serial monitor into the above bit of code (replacing our values).

Thats about all you need to know to get started. Upload the code to your FLORA, and you are ready to hit the road.
To test out your animations inside, try the following code that reacts to just the compass:
Download File
Copy Code 
#include <Adafruit_NeoPixel.h>
#include <LSM303.h>
// Test code for Adafruit Flora GPS modules
//
// 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

Adafruit_NeoPixel strip = Adafruit_NeoPixel(45, 6, NEO_GRB + NEO_KHZ800);
int FarRight = 9;
int CenterRight = 10;
int CenterLeft = 34;
int FarLeft = 35;
int HeadsUp[] = {35, 34, 10, 9};
int RightStrip[] = {46, 8, 7, 6, 5, 4, 3, 2, 1, 0, 46};
int RightCenterStrip[] = {11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21};
int LeftCenterStrip[] = {33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23};
int LeftStrip[] = {46, 36, 37, 38, 39, 40, 41, 42, 43, 44, 46};
int counter = 256*5;

#include <Wire.h>
#include <LSM303.h>

LSM303 compass;

void setup() {
  Serial.begin(9600);
  Wire.begin();
  compass.init();
  compass.enableDefault();
  
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
  
  // Calibration values. Use the Calibrate example program to get the values for
  // your compass. M min X: -561 Y: -679 Z: -558 M max X: 232 Y: 109 Z: 224
  compass.m_min.x = -561; compass.m_min.y = -679; compass.m_min.z = -558;
  compass.m_max.x = 232; compass.m_max.y = 109; compass.m_max.z = 224;
}

void loop() {
  compass.read();
  int heading = compass.heading((LSM303::vector){0,-1,0});
  
  //Use this part of the code to determine which way you need to go.
  if ((heading > 348.75)||(heading < 11.25)) {
    Serial.println("  N");
    //Serial.println("Forward");
    GoForward(strip.Color(0, 51, 20), strip.Color(255, 255, 0), 200);

  }
  
  if ((heading >= 11.25)&&(heading < 33.75)) {
    Serial.println("NNE");
    //Serial.println("Go Left");
    GoForward(strip.Color(0, 51, 10), strip.Color(255, 255, 0), 200);
  }  
  
  if ((heading >= 33.75)&&(heading < 56.25)) {
    Serial.println(" NE");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(11, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 56.25)&&(heading < 78.75)) {
    Serial.println("ENE");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(39, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 78.75)&&(heading < 101.25)) {
    Serial.println("  E");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(74, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 101.25)&&(heading < 123.75)) {
    Serial.println("ESE");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(74, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 123.75)&&(heading < 146.25)) {
    Serial.println(" SE");
    //Serial.println("Go Left");
    TurnLeft(strip.Color(79, 61, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 146.25)&&(heading < 168.75)) {
    Serial.println("SSE");
    //Serial.println("Go Left");
    TurnAround(strip.Color(79, 61, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 168.75)&&(heading < 191.25)) {
    Serial.println("  S");
    //Serial.println("Turn Around");
    TurnAround(strip.Color(79, 32, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 191.25)&&(heading < 213.75)) {
    Serial.println("SSW");
    //Serial.println("Go Right");
    TurnAround(strip.Color(79, 61, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 213.75)&&(heading < 236.25)) {
    Serial.println(" SW");
    //Serial.println("Go Right");
    TurnRight(strip.Color(79, 61, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 236.25)&&(heading < 258.75)) {
    Serial.println("WSW");
    //Serial.println("Go Right");
    TurnRight(strip.Color(74, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 258.75)&&(heading < 281.25)) {
    Serial.println("  W");
    //Serial.println("Go Right");
    TurnRight(strip.Color(74, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 281.25)&&(heading < 303.75)) {
    Serial.println("WNW");
    //Serial.println("Go Right");
  TurnRight(strip.Color(39, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 303.75)&&(heading < 326.25)) {
    Serial.println(" NW");
    //Serial.println("Go Right");
    TurnRight(strip.Color(11, 79, 0), strip.Color(255, 255, 0), 200);
  }
  
  if ((heading >= 326.25)&&(heading < 348.75)) {
    Serial.println("NWN");
    //Serial.println("Go Right");
    GoForward(strip.Color(0, 51, 10), strip.Color(255, 255, 0), 200);
  }
}

void TurnLeft (uint32_t c, uint32_t stripe, uint8_t wait) {
  strip.setPixelColor(CenterRight, 0);
  strip.setPixelColor(CenterLeft, 0);
  strip.setPixelColor(FarLeft, c);
      strip.show();
      for(uint16_t i=0; i<11; i++) {
      strip.setPixelColor(LeftCenterStrip[i], strip.Color(0, 0, 0));
      strip.setPixelColor(LeftStrip[i], strip.Color(0, 0, 0));
      strip.show();
      delay(30);
      }
      //delay(wait);
  strip.setPixelColor(FarLeft, 0);
  strip.show();
     colorWipe(stripe, 30);
      //delay(wait);
}

void TurnRight (uint32_t c, uint32_t stripe, uint8_t wait) {
  strip.setPixelColor(CenterRight, 0);
  strip.setPixelColor(CenterLeft, 0);
  strip.setPixelColor(FarRight, c);
      strip.show();
      for(uint16_t i=0; i<11; i++) {
      strip.setPixelColor(RightCenterStrip[i], strip.Color(0, 0, 0));
      strip.setPixelColor(RightStrip[i], strip.Color(0, 0, 0));
      strip.show();
      delay(30);
  }
      //delay(wait);
  strip.setPixelColor(FarRight, 0);
  strip.show();
      colorWipe(stripe, 30);
      //delay(wait);
}

void TurnAround (uint32_t c, uint32_t stripe, uint8_t wait) {
  strip.setPixelColor(CenterRight, c);
  strip.setPixelColor(CenterLeft, c);
      strip.show();
      for(uint16_t i=0; i<11; i++) {
      strip.setPixelColor(LeftCenterStrip[i], strip.Color(0, 0, 0));
      strip.setPixelColor(RightCenterStrip[i], strip.Color(0, 0, 0));
      strip.show();
      delay(30);
  }
      //delay(wait);
  strip.setPixelColor(CenterRight, 0);
  strip.setPixelColor(CenterLeft, 0);
  strip.show();
      colorWipe(stripe, 30);
      //delay(wait);
      
}

void GoForward (uint32_t c, uint32_t stripe, uint8_t wait) {
  strip.setPixelColor(CenterRight, c);
  strip.setPixelColor(CenterLeft, c);
      strip.show();
      for(uint16_t i=0; i<11; i++) {
      strip.setPixelColor(LeftCenterStrip[i], strip.Color(0, 0, 0));
      strip.setPixelColor(RightCenterStrip[i], strip.Color(0, 0, 0));
      strip.show();
      delay(30);
  }
      colorWipe(stripe, 30);
      //delay(wait);
}

// Slightly different, this makes the rainbow equally distributed throughout
void colorWipe(uint32_t c, uint8_t wait) {
for(uint16_t i=0; i<11; i++) {
      strip.setPixelColor(LeftCenterStrip[i], strip.Color(255, 255/i^16, 255/i^16));
      strip.setPixelColor(RightCenterStrip[i], strip.Color(255, 255/i^16, 255/i^16));
      strip.setPixelColor(RightStrip[i], strip.Color(255, 255/i^16, 255/i^16));
      strip.setPixelColor(LeftStrip[i], strip.Color(255, 255/i^16, 255/i^16));
      strip.show();
      delay(wait);
  }
}


// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  if(WheelPos < 85) {
   return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
  } else if(WheelPos < 170) {
   WheelPos -= 85;
   return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  } else {
   WheelPos -= 170;
   return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
}
 Build Circuit Wear it! 

This guide was first published on Jun 19, 2013. It was last updated on Jun 19, 2013.

This page (Program it) was last updated on May 22, 2022.

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