OpenChronograph Launches OC-1 Dev Kit, Converts Commercial Smartwatches Into Arduino Compatibles

Powered by an ATmega328P, the OC-1 mainboard is a drop-in replacement for popular proprietary hybrid smartwatches.

Gareth Halfacree
2 months agoWearables

The OpenChronograph project has started selling its first developer kits, allowing owners of suitable hybrid smartwatches to turn them into Arduino-compatible open hardware devices with a suite of handy built-in sensors.

"The majority of hybrid smartwatches available today (Skagen, Fossil) use [Soprod] micromotors, and many are based on the same Soprod reference board design," explains OC Labs' Scott Nietfeld. "The OpenChronograph mainboards are intended to be programmable drop-in replacements for a large number of commercial hybrid smartwatches, with a suite of handy sensors.

"Hybrid smartwatches are neat, and they can offer fantastic battery life compared to modern smartwatches. Unfortunately, experimenting with them is difficult due to the closed nature of available designs. This project is intended to open up hybrid smartwatch design to the maker community."

The OpenChronograph OC-1 Dev Kit is the first piece of hardware to come out of the project, and has been confirmed compatible with four hybrid smartwatches: the Skagen Connected and Hagen, and the Fossil Q Activist and Q Men's Machine.

Owners of these watches can pick up the kit, but with a clear warning: "Installing the OC-1 mainboard will require you to disassemble and reassemble your donor smartwatch — a delicate process which may result in cosmetic or functional damage. You should also expect to have to do some amount of debugging after reassembly to ensure that the micromotors are making good electrical contact and that there are no mechanical interferences preventing the output shafts from turning."

Those not put off by the idea of taking a watch apart will find inside the kit a mainboard powered by a Microchip ATmega328P microcontroller, an ultra-low-power RV-1085-C3 real-time clock, and two sensor platforms: The MPL3115A2 pressure/altitude/temperature sensor; and the MPU-9250 six degrees of freedom (6DoF) inertial measurement unit with three-axis magnetometer.

The board itself includes support for dual- and single-rotor micromotors, up to three hands, and full forward and retrograde hand movement. For ease of programming, test points are included for the MicroPogo Serial Programmer — though one is not included in the kit.

More information on the project can be found on the OpenChronograph GitHub repository, while the developer kit is available to purchase for $80 from the OC Labs Tindie store.

Nietfeld has also provided a closer look at the PCB manufacturing process for custom dials, like the one pictured above.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire:
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