Chronos is a smart disc intended to be attached to the back of any analog watch. With a dedicated app on a smartphone, it can be used to control music, get reminders, count steps and calories burned, control the phone’s camera shutter and more.


Business type

Internet of Things, Wearables


  • Digital Strategy
  • UI/UX Design
  • Android Development
  • Front & Back-end Web Development

Product description

Chronos is a 3mm thick disc that mounts on the back of almost any watch. A user connects it with their smartphone via Bluetooth and then can use it to track steps, get notifications, silence calls, tap it to find the phone and more.


  • The Android app was expected to be a clone of the iOS app, but obviously it needed to be adjusted to the platform’s guidelines and users’ habits
  • The app was required to work with a version of the firmware that was not yet finetuned and finalized at that moment


  • We made it possible to establish long-term connection between the smartphone and the disc on the Android SDK level (which is more flexible than a default system-level connection)
  • We implemented Third-party app notification parsing, which allowed users to set notifications of different vibration and color for the desired events related to other applications
  • Also, we gained even deeper experience with BLE for Android, RxJava 2, DFU, Google Fitness API, Custom Views

Tools used

Java, RxJava 2, Dagger 2, Fabric Crashlytics, Calligraphy

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