ESP32 Smartwatch

As for where this watch idea started — it began with wanting a regular digital watch that includes the functions I personally need and a battery that lasts around 3 to 4 weeks. Now, I'm starting to wonder if it might be a good idea to sell the PCB as an open-source project.

The main target users are people like us who are learning programming — so we can reprogram the watch however we like and use it the way we want. For now, since there’s no manufacturing cost yet, it’s still running on a breadboard.

The main processor used in this watch is the ESP32-C3. This processor supports both Wi-Fi and Bluetooth and is quite powerful. Since it can connect to the internet, if your programming skills are good, there are a lot of things you can do with it. (For example: using a weather API to display weather info on the watch or even controlling smart home devices from your house.) Also, since it includes an external RTC (Real-Time Clock), you can put the processor into deep sleep mode (which consumes very low power) when not using other functions and still use it as a regular watch.

It also includes an accelerometer, gyroscope, and heart rate sensor, so it can run algorithms for step counting, sleep tracking, and heart rate monitoring, among other features.

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2026 Update

In 2026, I refined the smartwatch firmware to make the overall experience smoother and more practical for daily use. I focused on improving power behavior, cleaning up the UI flow, and making core watch functions more reliable.

I also started preparing the project structure so it is easier for other learners to modify the code and test their own ideas. The goal is still the same: keep this as a programmable watch platform that is simple, open, and fun to build on.

Features

• Local time with seconds display
• 12h / 24h time format
• Date and weekday header
• Menu-based navigation system
• Manual time and date setting
• 4 configurable daily alarms
• Hourly chime (SIG)
• Stopwatch
• Countdown timer
• World time with adjustable UTC offset (-12 to +14)
• World map timezone display
• DS3231 temperature display (°C / °F)
• Moon phase screen
  • Waxing / waning visual
  • Lunar day display
  • Phase label
• Auto deep sleep mode
• Wake from buttons or RTC alarm
• Persistent settings storage

Settings

• 12h / 24h mode
• Hourly chime enable/disable
• Display invert preference
• Deep sleep enable/disable
• Sleep timeout configuration

Firmware Structure

The firmware is now organized into modular components to make the project easier to maintain, debug, and extend in the future.