EWatch
Pre-order EWatch.
EWatch is a programmable ESP32-S3 smartwatch and dev board. Code it by hand like any other Arduino board, or describe what you want and let an LLM write the firmware. You can buy it as a bare board, as a kit to build yourself, or ready to wear. I design and assemble them here in the UK.
Written about EWatch.
- circuit.rocks EWatch: An Open Source ESP32-S3 Smartwatch You Can Program Walks through the hardware, the open firmware and the three versions. Read the article ↗ (opens in a new tab)
- Hackster.io Build and Program Your Own Smartwatch On the five-year build, the power circuit and the open-source drivers. Read the article ↗ (opens in a new tab)
- LinuxGizmos ESP32-S3 powers EWatch smartwatch with open drivers and DIY options Covers the hardware, the three versions and the open-source drivers. Read the article ↗ (opens in a new tab)
Same board in all three.
The PCB
Just the board and the screen: ESP32-S3, USB-C, display connector, assembled and bring-up tested. Bring your own battery, strap and enclosure.
- EWatch mainboard (assembled)
- 1.69" touch display
Not on sale yet. EWatch is in certification. Leave your email and I will tell you when you can order.
The Kit
Every part of the watch, laid out for a one-afternoon build. PCB, screen, battery, vibration motor and strap, plus the case CAD files so you can print it, mill it or send it out.
- EWatch mainboard
- 1.69" touch display
- 350 mAh battery
- Vibration motor
- Strap
- Case CAD files (On request)
Not on sale yet. EWatch is in certification. Leave your email and I will tell you when you can order.
The Watch
Assembled, tested and pre-flashed. Charge it and start writing watch faces.
- Fully assembled EWatch
- Free USB-C programming cable
- Pre-flashed with latest EWatchOS
Not on sale yet. EWatch is in certification. Leave your email and I will tell you when you can order.
EWatch (models EW-PCB-01, EW-KIT-01, EW-ASM-01) will receive security updates until at least 31 December 2029.
Certification status
What EWatch has to pass before it ships: radio (EN 300 328), EMC (EN 301 489), electrical safety (EN 62368-1), RF exposure, and the UK product security rules for connected devices. The battery has to come with UN38.3 transport test evidence.
As deep as you want to go.
EWatch is a full ESP32-S3 development board, wrist-sized. Write the firmware yourself, the way you would on a Feather or a Watchy. Or paste the open-source drivers and one example project into an LLM and let it write the firmware for you.
Open-source drivers
Drivers for display, touch, IMU, BLE, charging and sleep modes. Call display.text(), imu.steps(), ble.notify(). Everything's on GitHub.
Reference watch faces
Working watch faces you can browse and fork in EWatch Cloud. Read one, change it, flash your version. They also make good context to hand an LLM, because the code already runs.
Vibe-code with an LLM
I run Claude Code inside PlatformIO with the driver headers and one example pasted in as context. Ask for a watch face that shows your next meeting and vibrates 5 minutes before: it usually works first try, because the model has real running code to copy from. When it doesn't, you end up reading the driver yourself.
Standard ESP32-S3 board
Underneath it's a vanilla ESP32-S3 dev board. Program it from Arduino IDE, PlatformIO, or ESP-IDF in C, C++, MicroPython or Rust.
Drop to the metal
Drive peripherals over I²C / UART, write to registers, fold it into your own RTOS task graph. The drivers are open source, so when you outgrow them you can read them.
From hobby to product
Start with the LLM. Drop to the driver layer when you need precision, or to bare-metal when you're counting microamps.
Hardware, documented.
From schematic to wrist.
EWatch Cloud.
EWatch Cloud is a browser-based studio: write firmware, compile it and flash it to the watch, with no toolchain to install. It'll come with an AI assistant grounded in real EWatch code, and a small marketplace so you can share or sell what you make. Still in development, arriving after the first watches ship.
Couldn't save that. Email contact@ewanwills.co.uk instead.