Getting the arrival API data for a specific stop on the Portland Trimet bus network, and lighting up an LED strip with the number of minutes before a bus arrives

trimet-next-arrival.ino

#include <ESP8266WiFi.h>
#include <WiFiClientSecure.h>
#include <TimeLib.h>
#include <NTPClient.h>
#include <WiFiUdp.h>
#include <Adafruit_NeoPixel.h>


//WIFI
const char* ssid = "[MY_SSID]";
const char* password = "[MY_PASSWORD]";

//const char* ssid = "Make + Think + Code";
//const char* password = "codethinkmake";


//API
const char* host = "developer.trimet.org";
String url = "/ws/V1/arrivals/locIDs/5901/appID/[MY_APP_ID]";
const int httpsPort = 443;
WiFiClientSecure client;


//TIME
#define NTP_OFFSET   -8 * 60 * 60 //Portland is UTC - 8
#define NTP_ADDRESS  "pool.ntp.org" //Default NTP Address
#define NTP_INTERVAL 30 * 1000    // how often to update in miliseconds
WiFiUDP ntpUDP;
//NTPClient timeClient(ntpUDP,NTP_ADDRESS,NTP_OFFSET, NTP_INTERVAL); //use the custom ntp params
NTPClient timeClient(ntpUDP); //use the ntp defaults

//LIGHTS
#define PIN      15
#define N_LEDS 9
Adafruit_NeoPixel strip = Adafruit_NeoPixel(N_LEDS, PIN, NEO_GRB + NEO_KHZ800);

void lightsOnImmediate() { //turn lights on with no delay
  for (uint16_t i = 0; i < strip.numPixels(); i++) {
    strip.setPixelColor(i, strip.Color(255, 255, 255));
    strip.show();
  }
}

void lightsOffImmediate() {
  for (uint16_t i = 0; i < strip.numPixels(); i++) {
    strip.setPixelColor(i, strip.Color(0, 0, 0));
    strip.show();
  }
}

void activateLights(int numLights) {
  Serial.println("activating lights");
  Serial.println(numLights);
  for (uint16_t i = 0; i < numLights; i++) {
    strip.setPixelColor(i, strip.Color(255, 255, 255));
    strip.show();
  }
}

//STATE
time_t timeEstimated; //when the next bus will come
time_t timeNow; //what time it is now
time_t timeDiff; //difference between now and estimated arrival

bool awaitingArrivals = true;
bool awaitingCurrentTime = true;
bool arrivalsRequested = false;

//CONFIG
int pollDelay = 30000; //time between each retrieval
int retryWifiDelay = 1000;


void setup() {
  Serial.begin(115200);
  strip.begin();

  //start time client to get real time
  timeClient.begin(); //start the thing that tells us the current time
  connectToWifi();
}

void connectToWifi() {

  //connect to wifi
  Serial.print("connecting to ");
  Serial.println(ssid);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) { //WAITING FOR WIFI
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

}

void getArrivals() {

  // Use WiFiClientSecure class to create TLS connection

  Serial.print("connecting to ");
  Serial.println(host);
  if (!client.connect(host, httpsPort)) {
    Serial.println("connection failed");
    delay(retryWifiDelay);
    return;
  }


  //Query the API
  Serial.print("requesting URL: ");
  Serial.println(url);

  client.print(String("GET ") + url + " HTTP/1.1\r\n" +
               "Host: " + host + "\r\n" +
               "User-Agent: BuildFailureDetectorESP8266\r\n" +
               "Connection: close\r\n\r\n");

  Serial.println("request sent");
  while (client.connected()) {
    String line = client.readStringUntil('\n');
    if (line == "\r") {
      Serial.println("headers received");
      break;
    }
  }


  String matchString = "";
  while (client.available()) {
    String line = client.readStringUntil('\r');
    if (line.endsWith("</resultSet>")) { //this signals the end of the response from XML API
      matchString = line;
    }
  }

  Serial.println(matchString); //log result xml response from server
  int lineEstimated = matchString.indexOf("estimated=");

  if (lineEstimated == -1) {
    Serial.println("NO ESTIMATED TIME!");
    turnSignOff();
    delay(retryWifiDelay);
    return;
  }

  int lineStart = lineEstimated + 11; //exclude `estimated="`
  int lineEnd = matchString.indexOf(" fullSign") - 4; //exclude ending zeroes and quote ( `000"` )
  String timeString = matchString.substring(lineStart, lineEnd);
  int timeInt = timeString.toInt();
  Serial.println("estimated arrival timestamp: ");
  Serial.println(timeInt);
  timeEstimated = timeInt; //assign this to a timestamp

  awaitingArrivals = false;

  client.stop();

}



void loop() {

  if (awaitingArrivals) {
    if (!arrivalsRequested) {
      arrivalsRequested = true;
      getArrivals();
    }
  } else {
    if (awaitingCurrentTime) {
      awaitingCurrentTime = false;
      getCurrentTime();
    }
  }
}

void getCurrentTime() {
  //get current time
  timeClient.update();
  timeNow = timeClient.getEpochTime();
  Serial.println("timeclient epoch time: ");
  Serial.println(timeNow);

  //get epoch time to next bus arrival
  timeDiff = timeEstimated - timeNow;
  showDuration(timeDiff);
}

void showDuration(time_t duration)
{

  int numMinutes;
  int numSeconds;

  // prints the duration in days, hours, minutes and seconds
  if (duration >= SECS_PER_DAY) {
    Serial.print(duration / SECS_PER_DAY);
    Serial.print(" day(s) ");
    duration = duration % SECS_PER_DAY;
  }
  if (duration >= SECS_PER_HOUR) {
    Serial.print(duration / SECS_PER_HOUR);
    Serial.print(" hour(s) ");
    duration = duration % SECS_PER_HOUR;
  }
  if (duration >= SECS_PER_MIN) {
    numMinutes = duration / SECS_PER_MIN;
    Serial.print(numMinutes);
    Serial.print(" minute(s) ");
    duration = duration % SECS_PER_MIN;
    numSeconds = duration;
  }
  Serial.print(duration);
  Serial.print(" second(s) ");

  if (numMinutes < 1) {
    turnSignOff();
  } else {
    showNumber(numMinutes);
  }

  resetCycle();

}

void turnSignOff() {
  lightsOffImmediate();
}

void showNumber(int numMinutes) {
  activateLights(numMinutes);
}

void resetCycle() {
  awaitingArrivals = true;
  awaitingCurrentTime = true;
  arrivalsRequested = false;

  Serial.println("hold display...");
  delay(pollDelay);
  Serial.println("poll again");
}