TinyWATCH S3
TinyWATCH S3 is an open source hackable smartwatch powered by an ESP32-S3 with touch display and a whole lot more. It is the ultimate wrist wearable ESP32-S3 development board.
TinyWATCH S3 is powered by an Espressif ESP32-S3 Dual Core MCU with 8MB of Flash and 2MB of additional PSRAM.
Touch Display
A 240x280 color TFT display (ST7789) with capacitive touch (CST816T) provides the primary interface. Swipe between watch faces, access apps, and interact with widgets. The display automatically dims and the watch goes to sleep after a configurable time, waking when you lift your wrist or tap the screen.
Sensors
TinyWATCH S3 packs a 6-axis IMU (BMI270) for step counting, gesture detection, and wrist-wake, a magnetometer (MMC5603) for compass functionality, and an I2S MEMS microphone (ICS-43434) for audio visualisation.
Haptics and Audio
A haptic motor driven by a DRV2605L provides tactile feedback for notifications and alarms. A magnetic buzzer provides audible alerts.
Battery Support
TinyWATCH S3 supports a 1S LiPo battery (maximum size 602530 -- 25x30mm and 6mm thick). Battery charging works even while the watch is powered off. An I2C fuel gauge (MAX1704X) monitors battery health, and a low-power RTC (RV-3028-C7) keeps accurate time even in deep sleep. Most users get a full day of use with a 400-450mAh battery.
A battery is not included -- you will need to source your own and solder it to the pads on the PCB.
Open Source
All hardware and firmware files for TinyWATCH live in the TinyWATCH S3 GitHub organisation. You will find KiCAD project files, schematics, iBOM files, case STL/STEP files, and 3D STEP files for the PCB. The firmware is developed in PlatformIO using the ESP32 Arduino Core framework.
What Ships in the Box
- TinyWATCH PCB (P10 revision)
- Capacitive Touch Display
- Black ABS 3D Printed Case (P10)
The watch arrives partially pre-assembled in the case. The case is designed to be used with Apple Watch (or compatible) bands.
Firmware
The firmware is in active development. Current features include digital and analog watch faces, community-contributed custom watch faces, an app framework (audio visualisation, compass, hello world example), a widget framework (OpenWeather, battery status), and a web interface for configuration. Time is set automatically via WiFi including DST.
For more information, please visit the TinyWATCH S3 product page.
Core Specifications
- ESP32-S3 -- 32Bit Dual Core 240MHz
- RISC-V ultra low power core
- 2.4GHz WiFi -- 802.11b/g/n
- Bluetooth 5, BLE + Mesh
- 8MB QSPI Flash
- 2MB Extra QSPI PSRAM
- USB-C Connector
- Reverse USB back-feed protection
- ESD protection on USB and buttons
- 5V presence detection
- LiPo Battery Charging
- Charge battery when watch power is off
- 700mA 3.3V LDO Regulator
- 5V Power (red), Charge (orange) LEDs
- Power On/Off Button
- 3D High Gain Antenna
Included Peripherals
- 240x280 Display (ST7789)
- Capacitive Touch (CST816T)
- I2C Battery Fuel Gauge (MAX1704X)
- I2C Low Power RTC (RV-3028-C7)
- I2C 6-Axis IMU (BMI270)
- I2C Magnetometer (MMC5603)
- I2S MEMS Microphone (ICS-43434)
- Magnetic Buzzer
- Haptics Motor (DRV2605L)
- Power On/Off Button
- Reset Button
- IO0/Boot Button
Updated on: February 8, 2026