What is NodeMCU ESP8266: Complete Guide

What is NodeMCU ESP8266: Complete Guide


Do you want to unravel the wonders of NodeMCU ESP8266, a diminutive yet potent Wi-Fi-enabled microcontroller board? if the answer is Yes! then check out our comprehensive guide which covers everything from board setup to programming, we provide all-encompassing information that caters to all skill levels. Whether you're a seasoned developer or a pro, our blog is a valuable source to unleash the potential of this impressive microcontroller. Get ready to be astonished by NodeMCU ESP8266's capabilities!

What is NodeMCU?

NodeMCU is open-source firmware, hardware, and software development environment project developed initially for the Node MCU ESP8266 Wi-fi SoC chip based on LUA. The most spectacular features are:

It is a low-cost, small and

powerful board. It is specifically designed for IoT applications. It is

compatible with Arduino IDE and micro python making prototyping a lot faster.

Because of all these features, Node MCU ESP8266 is the most popular and trending board in the

electronics market.

The below images show NodeMCU development board v0.9 and v1.0 (right).

What is NodeMCU

The v0.9 board is also called as 1st generation or V1 board. It is very wide and not convenient to use on a breadboard. This limitation is overcome by its next generation i.e 2nd generation or v1.0 or V2 board. This ESP8266 NodeMCU WiFi development board is more narrow and easy to fit on the breadboard. Also, the chip in this board is upgraded i.e. from ESP-12 to ESP-12E. 3rd generation board V3 is produced by LoLin which has minor improvements over the V2 board and is believed to have a more robust USB port than its predecessor(CH340G USB-TTL chip is used instead of Silabs CP2102 from V1.0). But again this board is wide making it difficult to use.

Since it can be connected to Internet it can be used in wide variety of applications like smart house,smart industrial devices, smart healthcare devices,etc.

read our blog esp8266 vs arduino, which compares the features of Arduino UNO and NodeMCU, two popular microcontrollers used in DIY projects.

Specifications & Construction:

Let’s look at the Node MCU ESP8266 specifications and construction of this module which makes it superior to its counterparts.

  • The onboard ESP8266 chip manufactured by Espressif Systems has an ESP8266EX core Wi-Fi SoC and a Tensilica L106 32-bit processor in the same chip.
  • Node MCU ESP8266 has 2.4GHz 802.11b/g/n Wi-fi with on-board antenna which supports WPA/WPA2. 
  • It has 17 GPIO, 11 are usable( 6 are used for communication with the onboard flash memory chip) and some of them support PWM. This GPIO can be used to interface ESP8266 NodeMCU with the external environment through sensors and actuators.
  • It also has UART, SDIO, SPI, I2C, I2S, and IR remote control peripheral interface.
  • It operates on 2.5-3.6V and average 80mA current with temperatures ranging from -40 to 125 C.


Specifications & construction of nodemcu


  • It comes in a QFN 32-pin ( 5mm * 5mm) package.
  • It supports firmware upgrades via UART download/ OTA (via network).
  • It also has SDK for customized development/cloud server development.

Let us look at the Node MCU ESP8266 pin diagram.


ESP8266 NodeMCU Pinout


Pins from D0-D8 can be used as GPIO pins.

Let's discuss these ESP8266 NodeMCU pin configuration in detail;

UART pins:

GPIO1 and GPIO3 are tx and rx pins respectively used for UART communication.

I2C pins:

D1 and D2 can be used SCL and SDA for I2C communication. 

Note that NodeMCU doesnt has hardware I2C pins. We can implement I2C in software on any GPIO pins.

SPI pins:

D5-D8 ( SCLK,MISO,MOSI,AND CS ) can be used for SPI communication.

You can see that in the above pinout diagram we have not labelled pins from GPIO6 to GPIO11. The reason they are not shown is they cannot be used for interfacing because they are connected ot the flash chip.

Analog Pin:

The pin marked as A0 on the silkscreen layer of PCB is the only pin which can analog read.

ESP8266 On-board LED:

On-board LED is connected to GPIO2.


Reset pin:

You can reset the ESP8266 NodeMCU board in 2 ways one is by pressing the reset button and other is by pulling the reset pin LOW.


Reset pin of NODEMCU


Reference: expressif

The block diagram of ESP8266EX is shown in figure 5 which explains the architecture of the chip.

How to upload programs to ESP8266 NodeMCU?

Following are the steps to upload program to ESP8266 NodeMCU:

1. Install the esp8266 by ESP8266 Community

Open Arduino IDE. Go to File> Preferences



Enter : https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json,http://arduino.esp8266.com/stable/package_esp8266com_index.json


Above two urls in additional boards manager URLs.

This URLs allow us to add additional boards in arduino IDE. ( above URLs add ESP32 and ESP8266 NodeMCU boards.)

Once done click Ok. 

Now go to Tools > Board > Boards Manager …



Now Install the esp8266 by ESP8266 Community.

2. Once installation is done upload your program by selecting the board


3. Open the blink sketch for ESP8266.


4. Select the appropriate COM port and click on upload.


Once uploading is done you will see led blinking on the board!!


The NodeMCU ESP8266! A powerful and versatile platform, it bestows upon us mere mortals a realm of endless possibilities for IoT applications and DIY projects. Affordable and simple to use, it has gained immense popularity among hobbyists and professionals alike, supported by a vast community. Through this comprehensive guide, you have been granted a solid comprehension of its inner workings and potential. Whether a novice or an expert, the NodeMCU ESP8266 is a must-have for your next project. So, what are you waiting for? Unleash the full scope of NodeMCU ESP8266 today!

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Frequently Asked Questions

1. What is NodeMCU ESP8266 module?

The NodeMCU ESP8266 module, a microcontroller that runs on the ESP8266 chip, boasting a diminutive form and pocket-friendly price. This little device enables developers to forge connections with the cyberspace and govern their projects from afar. It cooperates with the Arduino Integrated Development Environment, and allows for scripting in the Lua language or the Arduino programming language. It's a staple in IoT ventures, with potential to construct gadgets for domiciles, remote manipulation, and more.

2. Is NodeMCU and ESP8266 same?

NodeMCU, a development board, utilizes the ESP8266 chip as its core but offers more bells and whistles like built-in Wi-Fi and a USB-to-serial converter. Though not precisely identical, NodeMCU is constructed around ESP8266.

3. Why we use NodeMCU ESP8266?

The NodeMCU ESP8266 is an extensively employed development board in IoT applications, providing a versatile and cost-effective approach to connect devices to the internet. It features Wi-Fi and programming capabilities, facilitating speedy prototyping and deployment of IoT solutions. The board's adaptability with the Arduino IDE and a broad spectrum of libraries eases programming. With small dimensions and minimal power usage, it is optimal for a plethora of applications ranging from home automation to industrial control systems.

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