- 180mm x 32mm x 2.5mm flexible silicone bracelet
- 4.9″, 720×120 EPD (e-ink) screen (always on)
- Capacitive touchscreen
- Bluetooth 4.0
- Pulse and blood oximetry sensor
- Accelerometer/magnetometer (pedometer and compass)
- Notification vibration motor
The watch’s sensors will allow its users to monitor their health and set fitness goals. Its thin, flexible design should make it less obtrusive and more comfortable than existing devices, increasing the amount of data gathered. Furthermore, its open-source nature increases the user’s privacy, since there won’t be a manufacturer that can benefit from selling user data.
Additionally, I hope the development process will advance the hobbyist state of the art, especially with the custom touchscreen.
Development Strategy and Status
To ease development, sub-components will be developed individually, then integrated together into the final design.
I’ve already acquired the flexible display (and its development kit), as well as a flexible battery. The power supply circuitry has been developed and tested. Currently, other sub-components are being developed.
- Power supplies (complete)
- Microcontroller & BT
Open Source Licensing
All design files and source code will be released. The electrical design will included Eagle, Gerber, and schematic PDF files, as well as a complete bill of materials.
Software will be licensed under the GNU GPL version 3, with a linking exception for manufacturer-provided microcontroller support libraries. (The libraries provided by manufacturers are usually incompatible with the GPL.) All other files will be licensed under Creative Commons Attribution-Sharealike version 4.
An electrophoretic (e-ink) display requires a bunch of different power supply voltages. There are a few off-the-shelf chips (such as the TI TPS65185) which can provide all of them, but they’re physically too large. (To maintain flexibility, I’d like for each component to be less than 3mm wide.) As a result, the supplies must be generated by separate regulators. Selecting these regulators is a challenge, since they must be physically small while consuming very little power.
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