Send Sensor Data to Android Using Google Firebase & ESP8266

In this post, we will learn how to Send Sensor Data to Android Using Google Firebase & NodeMCU ESP8266.
Overview: Send Sensor Data to Android Using Google Firebase & ESP8266
In my earlier post, we learned how to
send and receive data using Google firebase
with NodeMCU ESP8266. We learned how to
upload
and
download
data to/from a
Firebase database
with
Arduino IDE
and
ESP8266 module
. Storing data (like sensors data) to a database that can be accessed from anywhere by the internet may be very useful. Firebase makes
storing
and
retrieving
data easy.
You can check the previous tutorial before proceeding for this new tutorial:

LED Control using Google Firebase & ESP8266

Send Real-Time Sensor Data to Google Firebase with ESP8266
In this tutorial we will learn
How to send Sensor Data to Android Application
Using
Google Firebase
&
Nodemcu ESP8266
. We will use
DHT11 Humidity & Temperature Sensor
to read the Temperature Humidity data of surrounding. We will send these sensor data to
Google Firebase Database
. We will then retrieve data from Google Firebase to
Android Application
. The Android application used here is designed using
MIT App Inventor
. Designing apps using MIT App Inventor is pretty easy. We will learn that too here.
What is Google Firebase?
Google Firebase
is a Google-backed application development software used for
creating, managing
,and
modifying data
generated from any
android/IOS application
, web services, IoT sensors & Hardware. To learn more about the
Google Firebase Console
, you can read the official
Google Firebase Documentation
from Google Firebase
Firebase Auth which is a service that can authenticate users using only client-side code. It supports social login providers Facebook, GitHub, Twitter and Google (and Google Play Games). Moreover, it includes a user management system whereby developers can enable user authentication with email and password login stored with Firebase.
Bill of Materials
Following are the
components
required for making this project. All the components can be easily purchased from
Amazon
. The component purchase link is given below.
S.N.
Components Name
Quantity
Purchase Links

NodeMCU ESP8266 Board

Amazon
AliExpress

DHT11 Sensor

Amazon
AliExpress

Micro-USB Cable

Amazon
AliExpress

Jumper Wires

Amazon
AliExpress

Breadboard

Amazon
AliExpress
Setting Up Hardware & NodeMCU DHT11 Circuit
Here is a circuit diagram for
connecting DHT11 Humidity Temperature Sensor with NodeMCU ESP8266 Board
. Connect the positive terminal of
DHT11
to 3.3V & negative terminal to GND. Connect the digital output pin to D2/GPIO4 of NodeMCU.
If you want to learn more about the DHT11 Humidity Temperature Sensor, you can follow this post:
Interfacing DHT11 Humidity Temperature Sensor with Arduino
You can assemble the circuit on breadboard as I used a breadboard for Assembly too. You can see the image below.
Now let us learn how we can
Send Sensor Data to Android Using Google Firebase & ESP8266
Installing Libraries
FirebaseArduino
is a library to simplify connecting to the Firebase database from Arduino clients. It is a full abstraction of
Firebase’s REST API
exposed through
C++
calls in a wiring friendly way. All
JSON
parsing is handled by the library and you may deal in pure C/Arduino types.
The library cannot work standalone. So you need to add the ArduinoJSON library as well.
1. ArduinoJSON Library
So first go to the library manager and search for “JSON” & install the library as shown in the figure below.
Note:
The latest JSON library might not work with the code. So you may need to downgrade the library to version
v5.13.5
2. Google FirebaseExtended Library
Now you need to install Google Firebase library as well. So, download the library from below link and add it to Library folder after extraction.
Download Google FirebaseExtended Library
3. DHT11 Library
To read the temperature and humidity we need any temperature humidity sensor. For that DHT11 is the best and cheap sensor. We need to install DHT11 Library for that. Download the library from below and add to the Arduino IDE.
Download DHT11 Library
Setting up Google Firebase Console Database
Now the main thing that we need to do is Setting up Google Firebase Console Database. Once the setup is done, we can then Send Real-Time Sensor Data to Google Firebase with Nodemcu ESP8266.
But I won’t be explaining here how you can set up the Google Firebase Console Database because I have already explained the entire process in the previous tutorial. You can check the following tutorial to learn how to do the setup.
IoT Based LED Control using Google Firebase & ESP8266
Once the setup is done you will get the following window.
Now we need to modify the Rules. For that click on rules and set all parameter to “true” which is initially set as “false”.
Designing Android App with MIT App Inventor 2
Now we need to design an
Android app
where we can monitor the sensor data in real-time. First, we will design the Android Application and then we will
Send Sensor Data to Android Phone Using Google Firebase & ESP8266
For desiging the Android App you can simply visit
http://ai2.appinventor.mit.edu/
. Then create an account and start a new project. The design view screen is shown below in the figure.
On the database part you need to enter the “
Firebase URL
” while leaving the “FirebaseToken” & “Projectbucket” blank.
While, if you look at the designer part of the block it looks something like this.
All you need to do is, Download the .aia file and import it to the MIT App Inventor Project. And then simply copy the URL of your google firebase database.
Download “FirebaseIOT” .aia File
Source Code: Send Sensor Data to Android Using Google Firebase & ESP8266

#define FIREBASE_HOST "mydhtsensor-26aa7.firebaseio.com"
#define WIFI_SSID "Alexahome"
#define WIFI_PASSWORD "12345678"
Before uploading the code, make sure to do the changes to
FIREBASE_HOST
. You can get this parameter from Google Firebase Console. Check the previous tutorial to learn more.
Also change the
WIFI_SSID
&
WIFI_PASSWORD
from the given code and replace it with your wifi SSID & Password.
Check the complete code here.

#include <ESP8266WiFi.h>
#include <FirebaseArduino.h>
#include "DHT.h"
#define FIREBASE_HOST "sensorandroid-42dd6.firebaseio.com"
#define WIFI_SSID "Alexahome" // Change the name of your WIFI
#define WIFI_PASSWORD "xstevedore1" // Change the password of your WIFI
#define DHTPIN D2
#define DHTTYPE DHT11 // DHT 11
DHT
dht
(
DHTPIN
DHTTYPE
)
;
void
setup
(
)
{
Serial
begin
(
115200
)
;
dht
begin
(
)
;
//reads dht sensor data
WiFi
begin
(
WIFI_SSID
WIFI_PASSWORD
)
;
Serial
(
"Connecting to "
)
;
Serial
(
WIFI_SSID
)
;
while
(
WiFi
status
(
)
!=
WL_CONNECTED
)
{
Serial
(
"."
)
;
delay
(

)
;
}
Serial
println
(
)
;
Serial
(
"Connected"
)
;
Serial
(
"IP Address: "
)
;
Serial
println
(
WiFi
localIP
(
)
)
;
Firebase
begin
(
FIREBASE_HOST
)
;
}
void
loop
(
)
{
float
h
=
dht
readHumidity
(
)
;
float
t
=
dht
readTemperature
(
)
;
// Reading temperature as Celsius (the default)
Serial
(
"Humidity: "
)
;
Serial
(
h
)
;
Serial
(
"% Temperature: "
)
;
Serial
(
t
)
;
Serial
println
(
"°C "
)
;
Firebase
setFloat
(
"Temp"
t
)
;
Firebase
setFloat
(
"Humidity"
h
)
;
delay
(
3000
)
;
}
Code Explanation
First, we include the library for Firebase & DHT11 Sensor

#include <ESP8266WiFi.h>
#include <FirebaseArduino.h>
#include "DHT.h"
Then we define the
FIREBASE_HOST
. We get this from Google Firebase Setup. This enables the data exchange between the ESP8266 and the firebase.

#define FIREBASE_HOST "*********************.firebaseio.com"
Then we define the WiFi SSID & Password. Repla