ESP32 Smart Watch

This project started as an idea to build a smartwatch completely from scratch instead of using existing development boards or modules. I wanted to design something compact, wearable, and fully custom — including the electronics, enclosure, firmware, and mobile app.

The smartwatch is based on the ESP32-S3-MINI-1-N8 and includes Bluetooth connectivity, a heart rate sensor, gyroscope/IMU, RTC, vibration motor, USB-C charging, and a touch display connector. Everything is integrated onto a circular PCB designed specifically for a smartwatch form factor.

PCB Design

The entire schematic and PCB were designed in KiCad. One of the biggest challenges was fitting all the components onto a small circular board while still keeping routing clean and making sure power delivery and RF performance were reliable.

The board includes:

• ESP32-S3-MINI-1-N8
• BQ24090 battery charging IC
• TPS63001 buck/boost converter
• MAX30102 heart rate sensor
• ICM-42670-P gyroscope/IMU
• RTC module
• USB-C interface
• vibration motor driver

After finishing the PCB design, I generated the Gerber, BOM, and Pick-and-Place files directly from KiCad and uploaded them to JLCPCB. I used their PCB assembly service so most of the SMD components were assembled automatically. That saved a huge amount of soldering time and made the prototype much cleaner and more reliable.

Once the boards arrived, I soldered the remaining components by hand, assembled the battery and display, and started firmware testing.

3D Printed Enclosure

To turn the electronics into an actual wearable device, I designed a custom case around the PCB dimensions and display layout. The enclosure was modeled for 3D printing and adjusted several times to improve button placement, charging access, and overall comfort.

The goal was to make it feel like a real smartwatch instead of just a prototype board in a box.

Firmware

The firmware was written specifically for the ESP32-S3 and handles:

• Bluetooth communication
• sensor data collection
• display communication
• RTC synchronization
• power management
• vibration feedback

Battery life was an important part of the project. With the current setup, the smartwatch lasts around one full day on a charge depending on Bluetooth usage and display activity.

Mobile Application

I also developed a companion mobile application using Qt. The app communicates with the watch over Bluetooth and allows sensor data monitoring and device interaction.

Qt made it possible to build a clean cross-platform interface while keeping Bluetooth communication relatively straightforward.