What is ESP32 in IoT?

Jul 22, 2025
Microcontroller
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What is ESP32 in IoT?

Device Overview

What is ESP32?

ESP32 is a powerful, low-cost, low-power microcontroller board developed by Espressif Systems. It comes with integrated Wi-Fi, Bluetooth, and a dual-core processor, making it a perfect choice for modern IoT (Internet of Things) and embedded applications. It is the successor of the popular ESP8266 board but offers much more processing power, GPIOs, and peripherals.

Key Features of ESP32

  • Processor: Dual-core Tensilica LX6 @ up to 240 MHz

  • Wi-Fi: IEEE 802.11 b/g/n

  • Bluetooth: v4.2 BR/EDR and BLE

  • GPIO Pins: 34 programmable I/O pins

  • Flash Memory: Typically 4MB (up to 16MB)

  • RAM: 520KB SRAM + External RAM supported

  • Operating Voltage: 3.3V

  • ADC Channels: 12-bit (up to 18 channels)

  • DAC Channels: 2 (8-bit)

  • PWM: Supported on all GPIOs

  • Touch Sensor Support: Up to 10 touch inputs

  • SPI, I2C, UART, CAN, I2S support for interfacing

  • Ultra Low Power (ULP) Co-processor for low-power applications

ESP32 Board Types

Board Name Description
ESP32-WROOM-32 Most commonly used, built-in antenna, general-purpose
ESP32-WROVER Includes external PSRAM, great for camera/audio processing
ESP32-S2 Single-core with improved security features
ESP32-C3 RISC-V-based, compact and power-efficient
ESP32-S3 Dual-core with AI instructions and USB OTG support
NodeMCU-32S Developer-friendly with USB interface
TTGO T-Display Built-in LCD screen, battery support
 

ESP32 Pinout (Basic Reference)

  • Power Pins: 3V3, GND, EN

  • Digital I/O: GPIO0 – GPIO39

  • Analog Input: GPIO32–39 (ADC1), GPIO0, 2, 4, 12–15, 25–27 (ADC2)

  • PWM Output: All digital pins

  • UART: GPIO1, GPIO3 (default), others configurable

  • SPI/I2C: User-defined (via software libraries)

Note: Some GPIOs are input-only or reserved during boot (e.g., GPIO6–11 used for flash memory).

Why Use ESP32?

  • Built-in Wi-Fi & Bluetooth – no need for external modules
  • Faster than Arduino & ESP8266
  • Supports advanced features like touch, DAC, CAN
  • Ideal for IoT, home automation, wearable tech, and industrial monitoring
  • Excellent community support & Arduino IDE compatibility

Programming ESP32

ESP32 can be programmed using:

  • Arduino IDE

  • ESP-IDF (Espressif IoT Development Framework)

  • PlatformIO

  • MicroPython

Popular libraries:

  • WiFi.h for Wi-Fi

  • BluetoothSerial.h for Bluetooth

  • ESPAsyncWebServer.h for web-based control

  • Adafruit_Sensor.h and others for interfacing

Real-Life IoT Example Project: Light ON/OFF Using ESP32 and Relay

Components Required

  • ESP32-WROOM-32
  • 5V Relay Module
  • Light Bulb or LED
  • 220V AC Supply (for bulb) or 5V DC (for LED)
  • Jumper wires, Breadboard

Circuit Diagram (Basic Overview)

ESP32 GPIO (e.g., GPIO 23) ---> Relay IN
ESP32 GND --------------------> Relay GND
ESP32 3.3V -------------------> Relay VCC
Relay COM & NO ---> AC Bulb or LED
Code Example (Using Arduino IDE)
#define RELAY_PIN 23

void setup() {
    pinMode(RELAY_PIN, OUTPUT);
    digitalWrite(RELAY_PIN, LOW); // Keep light OFF initially
    Serial.begin(115200);
}

void loop() {
    digitalWrite(RELAY_PIN, HIGH); // Light ON
    delay(5000);
    digitalWrite(RELAY_PIN, LOW);  // Light OFF
    delay(5000);
}
 

Output:

Light turns ON for 5 seconds and then OFF for 5 seconds in a loop.

Applications of ESP32

  • Home Automation Systems

  • Wi-Fi/Bluetooth based IoT Devices

  • Smart Sensors & Data Loggers

  • Agricultural Automation

  • Industrial Monitoring

  • Audio Processing Systems

  • AI on the Edge (ESP32-S3)

Advantages of ESP32

  • Integrated connectivity (Wi-Fi + BT)
  • Cost-effective
  • Versatile GPIO
  • Wide range of applications
  • Support for OTA (Over-The-Air updates)
  • Secure (HTTPS, SSL/TLS support)

Limitations of ESP32

  • Requires 3.3V logic level
  • Some GPIOs are boot-sensitive
  • Slightly complex for beginners vs Arduino Uno
  • High current draw during Wi-Fi transmission
 
 
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Frequently Asked Questions

Common questions about What is ESP32 in IoT?. Find answers to the most frequently asked questions.

ESP32 is used for developing wireless communication-based embedded systems. It supports Wi-Fi and Bluetooth, making it ideal for applications like automation, sensors, and smart devices.
Yes, ESP32 offers better speed, built-in Wi-Fi and Bluetooth, more GPIOs, and additional features compared to basic Arduino boards, making it more powerful for modern embedded applications.
Absolutely. ESP32 is fully compatible with the Arduino IDE after installing the ESP32 board package, making development easy for both beginners and experienced developers.
ESP32 is more advanced than ESP8266, offering dual-core CPU, Bluetooth support, more GPIOs, and better power management, while ESP8266 is limited to single-core and Wi-Fi only.
Yes, ESP32 supports both Bluetooth Classic and BLE (Bluetooth Low Energy), allowing it to connect with a wide range of Bluetooth-enabled devices and applications.
ESP32 typically runs on 3.3V. You can power it using a 5V USB supply via onboard voltage regulator, but direct connection to more than 3.3V on GPIO pins may damage the board.

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