Have you ever thought of building your own smartwatch instead of buying one? In this blog, I'll walk you through how I created a DIY Smartwatch using the ESP32 microcontroller and a small OLED display. This project packs some really cool features like:

  • Analog Clock Mode
  • Digital Clock Mode (12/24 hr)
  • Weather Information (live from API)
  • Stopwatch with millisecond precision
  • Timer with custom seconds input
  • Automatic Time Sync via NTP (so even after power off, time stays correct!)

Perfect for DIY electronics lovers, IoT beginners, and makers who want to explore what's possible with a tiny chip and some creativity.

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Components You'll Need

  • ESP32 Development Board
  • 0.96" OLED Display (I2C, SSD1306 driver)
  • Jumper wires & breadboard (or you can solder later for a wearable form)
  • Micro USB cable for programming
  • (Optional) A 3D-printed watch case

Circuit Diagram

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The circuit is very simple — just connect the OLED display via I2C:

  • VCC → 3.3V
  • GND → GND
  • SCL → GPIO 22
  • SDA → GPIO 21

I used the Arduino IDE for coding. You'll need to install from Arduino IDE Library:

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  • Adafruit_SSD1306 & Adafruit_GFX libraries
  • ArduinoJson for parsing API responses
  • WiFi & HTTPClient (already in ESP32 core)

👉 Important:

  • Put your WiFi SSID & password in the code.
  • Get a free Weather API key from WeatherAPI.com .

In the code, just paste your key where it says YOUR_API_KEY_HERE.

You can Download the code HERE or from HERE (docs)

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For now i set only these city's time zone but you can add more cities according to your need from this Github repo.

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Features in Action

After uploading, open the Serial Monitor to get the ESP32's IP address. Open that IP in your browser → You'll see a Web UI where you can switch modes easily from your phone or PC.

  1. Analog Clock 🕰️ — A clean, minimal clock face with date.
  2. Digital Clock 🕒R — ig bold numbers, date & day clearly visible.
  3. Weather Info 🌦️ — Current weather, temperature, and condition of any city (updates every 5 minutes).
  4. Stopwatch ⏱️ — Ultra-fast with start, stop, and reset controls.
  5. Timer ⏳ — Set in seconds and get an accurate countdown.

And the best part → Time never drifts. Even if you turn off ESP32, it resyncs via NTP when powered on.

Why This Project is Special

  • No need for an RTC module — NTP keeps time correct.
  • Portable IoT project that can be extended (fitness tracker, notifications, etc.).
  • Works like a mini smartwatch but costs less than $10.
  • You can learn about APIs, IoT, and OLED graphics in one project.

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