Sample code for using Firebase database with NodeMCU

nodemcu-firebase.cpp

#include <ESP8266WiFi.h>
#include <FirebaseArduino.h>

// Firebase
#define FIREBASE_HOST "yourfirebasedatabase.firebaseio.com"
#define FIREBASE_AUTH "*****"

// Wifi
#define WIFI_SSID "your_wifi_ssid"
#define WIFI_PASSWORD "your_wifi_password"

const int led = D1;

void setup()
{
  Serial.begin(115200);
  pinMode(led, OUTPUT);

  // connect to wifi.
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.println("connecting...");
  while (WiFi.status() != WL_CONNECTED)
  {
    Serial.println(".");
    delay(3000);
  }
  Serial.println(WiFi.localIP());

  //  Setting up connection to firebase
  Firebase.begin(FIREBASE_HOST, FIREBASE_AUTH);
}

void loop()
{
   bool isLedOn = Firebase.getBool("/led");
   if (isLedOn) {
      digitalWrite(led, HIGH);
   }
   else {
      digitalWrite(led, LOW);
   }
   delay(1000);
}