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ESP32 Over-The-Air (OTA) Firmware Updates: A Step-by-Step Guide


Over-The-Air (OTA) firmware updates are a critical component of any IoT project. They allow you to remotely update the firmware on your devices, ensuring that they stay secure, bug-free, and feature-rich without requiring physical access. In this tutorial, we will explore how to implement OTA firmware updates on the ESP32, a versatile microcontroller popular for IoT applications.

Materials You'll Need:

  1. ESP32 development board (e.g., ESP-WROOM-32)

  2. USB cable for power and programming

  3. Computer with the Arduino IDE installed

Step 1: Install the Arduino IDE and ESP32 Board Package

If you haven't already, download and install the Arduino IDE from the official Arduino website (

Next, set up the Arduino IDE for ESP32 development:

  • Open the Arduino IDE.

  • Go to "File" > "Preferences."

  • In the "Additional Boards Manager URLs" field, add the following URL:arduinoCopy code

  • Click "OK" to close the Preferences window.

Step 2: Install the ESP32 Board Package

  • Go to "Tools" > "Board" > "Boards Manager..."

  • In the Boards Manager, type "esp32" in the search bar.

  • Click "Install" on the "esp32" by Espressif Systems package.

Step 3: Write the OTA Firmware Update Sketch

We'll create a basic OTA firmware update sketch that you can use as a starting point. Replace the placeholders with your Wi-Fi credentials and your server's URL for hosting firmware updates.

#include <Arduino.h>

#include <WiFi.h>

#include <ESPmDNS.h>

#include <WiFiUdp.h>

#include <ArduinoOTA.h>

const char* ssid = "YourSSID"; // Replace with your Wi-Fi SSID

const char* password = "YourPassword"; // Replace with your Wi-Fi password

void setup() {



// Connect to Wi-Fi

WiFi.begin(ssid, password);

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

Serial.println("Connection Failed! Rebooting...");




// Initialize OTA



ArduinoOTA.setPassword("YourOTAPassword"); // Replace with your OTA password


Serial.print("IP address: ");



void loop() {


// Your loop code here


Step 4: Configure OTA Settings

  • Replace "YourSSID" and "YourPassword" with your Wi-Fi network credentials.

  • Modify "YourOTAPassword" to set a password for OTA updates (optional but recommended for security).

Step 5: Upload the Sketch

  • Connect your ESP32 to your computer using a USB cable.

  • Ensure you've selected the correct board and port (as described in previous steps).

  • Click the "Upload" button (right arrow) in the Arduino IDE to compile and upload the sketch to your ESP32.

Step 6: Monitor OTA Updates

  • Open the Serial Monitor (Tools > Serial Monitor) to monitor the ESP32's serial output.

  • After uploading, the ESP32 will connect to Wi-Fi and print its IP address.

  • You can now wirelessly upload new firmware updates to your ESP32 using the Arduino IDE's OTA capabilities.

Step 7: Perform an OTA Update (Arduino IDE)

To perform an OTA update:

  • Make changes to your sketch.

  • Compile the sketch (Sketch > Verify/Compile).

  • Click "Sketch" > "Export compiled Binary" to generate the firmware file.

  • Host the firmware file on a server accessible via HTTP.

Step 8: OTA Update from Arduino IDE

  • In the Arduino IDE, go to "Sketch" > "OTA Update" > "Browse..."

  • Select the firmware binary file you exported.

  • Enter the IP address of your ESP32 and the OTA password.

  • Click "Upload" to perform the OTA update.

Step 9: Testing the OTA Update

Your ESP32 will receive the OTA update, restart, and run the new firmware. Monitor the Serial Monitor to verify the update process's success.


Implementing OTA firmware updates on the ESP32 is a valuable skill for IoT projects. It allows you to remotely and securely update your devices, ensuring they stay current and robust over time. You can further enhance this basic OTA update sketch with advanced features like version checking and rollback mechanisms to ensure the reliability of your updates.

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