zswatch.dev

_{ZSWatch v4 CNC:ed Stainless Steel (left), Clear Resin 3D print (right)}

WatchDK - The ZSWatch development kit ($99) has the same nRF5340 chip and sensors as the final watch, in a larger form factor for development and debugging. Battery optional, runs off USB-C.

Order from Elecrow

Quick Start

About

Smartwatch built from scratch, both hardware and software. Built on the Zephyr™ Project RTOS, hence the name ZSWatch (Zephyr Smartwatch).

_{ZSWatch Development Kit (WatchDK)}

https://github.com/ZSWatch/ZSWatch/assets/4318648/ec1a94fd-a682-4559-9e68-f3e5bfcbe682

Documentation

Full documentation is available at zswatch.dev:

• Getting Started - WatchDK quick start guide
• Toolchain & Compiling - Environment setup, building, and flashing
• Writing Apps - How to create applications for ZSWatch
• Hardware Design - PCB design documentation

Features

Hardware

• nRF5340 BLE chip (u-blox NORA-B10 module)
• 128 MHz Dual core
• 512 KB RAM
• 1 MB Flash
• 30 MHz SPI for display
• 240x240 round display with touch screen
• IMU Bosch BMI270 for gesture navigation, wrist-wake, step counting
• Bosch BMP581 High-performance pressure sensor (~20 cm accuracy)
• ST LIS2MDLTR Magnetometer
• Macronix MX25U51245GZ4I00 64 MB external flash
• Broadcom APDS-9306-065 Light Sensor for automatic brightness control
• Micro Crystal RV-8263-C8 RTC for time keeping and alarm functions
• Knowles SPK0641HT4H-1 I2S microphone for audio recording
• Nordic nPM1300 PMIC for power and system management
• Speaker (Requires HR Extension Board)

PCB

All hardware is designed in KiCad. Hardware repos:

• Watch PCB - 38 mm diameter watch PCB
• Watch DevKit PCB - Larger development board with breakout headers and debug header
• Extension PCB - Health and audio addon PCB
• Dock/Breakout PCB - USB-C breakout for debugger and UART access

HR Extension Board (WIP)

The Extension PCB is a small add-on board (approximately 16.8 mm diameter) that plugs into the WatchDK headers. It is still in development and the design, BOM, and firmware support may change.

More background and progress updates: - https://zswatch.dev/blog/dk-and-hr-integration - https://zswatch.dev/blog/progress-hw-xip-usb-power - https://zswatch.dev/blog/progress-hr-fota

Key BOM highlights: - Analog Devices / Maxim MAX86141 optical AFE + ams OSRAM SFH 7016 (RGB/IR LED module) + Vishay VEMD8082 photodiodes - Analog Devices / Maxim MAX32664 biometric sensor hub - Renesas / Dialog DA7212 audio codec (speaker support) - Amphenol 101P014FB110 board-to-board connectors

Software

• Bluetooth LE communications via the ZSWatch Companion App (iOS/Android) or GadgetBridge (Android)
• Multiple watchfaces (dynamically switchable), showing time, date, battery, weather, steps, notifications, environmental data, and more
• Pop-up notifications
• Application picker with extensible app framework
• Settings, Music control, Compass, and many more
• Step counting, gestures, and much more

The watch also supports ESP32 watchfaces from Felix Biego. See this fork for details.

Smartphone Communication

iOS (recommended): Use the official ZSWatch Companion App on the App Store. ZSWatch also supports native Apple Notification Center Service and Apple Media Service.

Android (experimental companion app): The ZSWatch Companion App currently requires invite access. Request access via Discord or email mail@zswatch.dev. For a stable experience, use GadgetBridge.

See phone setup on zswatch.dev for details.

Enclosure/Casing

3D-printed casing with 3D-printed buttons, with an option for CNC:ed metal casing.

Getting a WatchDK or Building Your Own

For development: The WatchDK ($99) is the recommended starting point. It has the same nRF5340 SoC, sensors, and display as the final watch, with breakout headers, USB-C with SWD/UART, power measurement headers, and a debug header. Everything except battery is included. Battery is optional.

Order WatchDK from Elecrow: www.elecrow.com/zswatch-development-kit.html

For DIY builders: Head over to the hardware repos for the for ordering information. The final miniature watch hardware is still being developed.

Demos

• HTTP requests over BLE through Gadgetbridge
• Watchfaces

Developing

See the Toolchain & Build Guide for environment setup, compiling, and flashing.

To learn how to write apps for ZSWatch, see Writing Apps.

Licence GPL-3.0

The main difference from MIT is that if anyone wants to build something more with this, they need to also open source their changes back to the project, which I think is fair, so everyone can benefit from those improvements. If you think this is wrong, feel free to contact me and I'm open to change the licence.

Thanks

Funding

This project is partly funded through NGI0 Commons Fund, a fund established by NLnet with financial support from the European Commission's Next Generation Internet program. Learn more at the NLnet project page.

Support

PCBWay for sponsoring the manufacturing and assembly of prototype PCBs. PCBWay is the recommended manufacturer for PCBs and assembly of ZSWatch.

Miscellaneous

• Watch my presentation at Zephyr Developer Summit 2023