NodeMCU ESP8266

NodeMCU is a microcontroller board developed using the ESP8266 chip from Espressif, which is notable for:

Built-in Wi-Fi connectivity
cheap price
Easy to use with Arduino IDE
Suitable for IoT (Internet of Things) such as controlling devices via the Internet, sending sensor data to the web, making a smart home.

The name "NodeMCU" stands for "Node MicroController Unit" and was originally written in Lua, but is now more commonly written in C/C++ via the Arduino IDE.

NodeMCU ESP8266 Specifications

list	details
Main chip	ESP8266 (ESP-12E or ESP-12F)
CPU speed	80 MHz (Overclockable up to 160 MHz)
Memory (Flash)	4MB
SRAM (RAM)	64KB
Wi-Fi	802.11 b/g/n (2.4GHz), supports both STA and AP
Working pressure	3.3V (but USB can use 5V because it has a built-in converter)
USB port	Use CH340 or CP2102 chip (for programming via USB)
Number of GPIOs	11 legs (some legs have special functions such as PWM, ADC, I2C, SPI)
ADC leg	1 leg (reads analog values 0–1V)
Digital leg pressure	3.3V (If using with 5V, a voltage divider resistor is required)

3. Using NodeMCU ESP8266

Highlights:

Built-in Wi-Fi connectivity (no separate module required)
You can load the code via USB.
Works with the web, phones, and online databases.
Supports writing with Arduino IDE or PlatformIO

Popular usage examples:

✅ Control light bulbs via Wi-Fi

✅Write a built-in web server, control it via a web browser.

✅ Send sensor data (DHT11, MQ-2, Soil) to Firebase / ThingSpeak

✅ Make a node to send data via Wi-Fi to a server or MQTT.

✅ Create a notification system via LINE Notify or Telegram.

Code sample: Open a simple web server

include <ESP8266WiFi.h>

const char* ssid = "YOUR_WIFI_NAME";

const char* password = "YOUR_WIFI_PASSWORD";

WiFiServer server(80);

void setup() {

Serial.begin(115200);

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {

delay(1000);

Serial.println("Connecting to WiFi..."); }

Serial.println("Connected: ");

Serial.println(WiFi.localIP());

server.begin();

}

void loop() {

WiFiClient client = server.available();

if (client) {

client.println("HTTP/1.1 200 OK");

client.println("Content-Type: text/html");

client.println();

client.println("<h1>Hello from NodeMCU!</h1>");

delay(1000);

}