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Notification Alert using ESP8266 - IoT

Updated: Apr 5

In different IoT projects and applications, notifications or alerts play an important role. Notification/alarms are used to notify the user about something important. Alerts can be in different forms such as LED indication, buzzer indication, vibration, a mobile notification. In this project, we will be exploring ' how to push notification alert using esp8266 and the Blynk app'.

Hardware requirements

Esp8266 / Node MCU

Node MCU

NodeMCU is an open-source firmware and development kit. It has SoC WiFi.

  • Input voltage: 7 V to 12 V.

  • 16 digital GPIO pins

  • 1 SPI

  • 1 I2C

  • 2 UART

  • On-chip RAM - 128kb

  • On-chip ROM - 4Mb

Ultrasonic sensor.

HC SR 05
Ultrasonic sensor

The ultrasonic sensor transmits sound waves at high frequencies.

  • The ultrasonic sensor works on the principle of speed = distance/time.

  • 5V DC power supply requirement.

  • Angle deviation - 15 degrees.

  • Range - 3 cm to 4 m.



Breadboards are electronic circuit prototyping boards. Breadboards are available in various sizes. Many electronic components such as sensors, actuators, display modules, IoT boards can be interfaced using a breadboard.

Jumper wires

Jumper wires
Jumper wires

Jumper wires are used for connecting terminals of electronic devices. Jumper wires are used to connect header pins on the circuit boards to each other and the breadboard. Male to male, female to female, and male to female are the types of jumper wires available.


Blynk android application

  • Blynk is an open-source IoT platform used for monitoring, data analytics, machine learning.

  • Blynk allows creating amazing interfaces for your projects using different widgets.

  • Blynk server establishes a connection between hardware and the Blynk app. WiFi, Bluetooth, GSM, USB, Ethernet can be used for connecting to the Blynk Cloud.

Arduino IDE

  • Arduino IDE is open source software used to write Arduino code, compile and upload it to any Arduino board. Program written in Arduino IDE is called a sketch.

  • Arduino sketch files are saved with extension .ino. Before compiling, uploading any Arduino sketch, the correct development board and COM port need to be selected.

  • Many inbuilt libraries and example sketches are also available in Arduino IDE.

Circuit diagram

There are 4 pins on the ultrasonic sensor HC SR 05.

  • VCC pin of HC SR 04 is connected to VCC pin of esp8266.

  • GND pin of HC SR 04 is connected to the GND pin of esp8266.

  • The trigger pin of HC SR 04 is connected to the D2 pin of esp8266.

  • Echo pin of HC SR 04 is connected to the D1 pin of esp8266.

Procedure on the Blynk app

Blynk app homescreen
Blynk app homescreen
  • First of all, create a new project and enter the project name. Now you have to select a widget from the widget box.

New project settings
New project settings
  • Select hardware Node MCU. Select connection type as WiFi. Choose any theme. Now click on 'Create'.

Gauge settings
Gauge settings
  • To get the widget box click on the place icon available in the top right corner.

  • Select a gauge to represent distance. Give a name to gauge as distance, select pin V5 as an input pin. Give label as cm. Select refresh rate, save option is not there these setting get automatically saved.

  • Select a notification alert from the widget box and keep its settings as default. You will get an authentication token in your mail.



As we start to run our project. Distance is calculated and sent to the Blynk server. Then the data is sent from the Blynk server to the Blynk app. The gauge on the Blynk app shows distance measured using an ultrasonic sensor. According to our logic in the code, when the distance becomes less than or equal to 10 cm. an alert ( notification ) is shown on the Blynk app. In the alert message, the argument passed in Blynk. notify() function is displayed.

Video By - Abhishek Goud


In this article, we measured and monitored distance. We used the Blynk IoT platform to push notifications. Similarly, this concept can be used to push notifications in different applications. In different IoT projects, notifications are required to be sent. We can use notifications in projects like temperature measurement, water level monitoring, gas detection, smoke detection, and many more.


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Anushka Gupta
Anushka Gupta
Jul 27, 2023

This blog post on Notification Alert using ESP8266 - IoT is a gem! Learn Electronics India did an outstanding job in presenting the topic in a concise yet thorough manner. The troubleshooting tips and potential challenges covered in the article were a lifesaver. Highly recommended.


Short and effective! LearnElectronics India never disappoints.

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