Chronio – Low power Arduino based (smart)watch

Chronio is an Arduino-based 3D-printed Watch. By not including fancy Wifi and BLE connectivity, it gets several months of run time out of a 160mAh button cell. The display is an always-on 96×96 pixel Sharp Memory LCD. If telling the time is not enough, you can play a simplified version of Flappy Bird on it.
DIY watches often consist of a pcb and screen wrapped in duct tape. I wanted to change that by designing a 3D-printed case. It is closely oriented on the Pebble Time.Chronio – Low power Arduino based (smart)watch


  • Microcontroller: Atmega328p with Arduino bootloader
  • Real Time Clock: Maxim DS3231 (<2min per year deviation)
  • Display: 96×96 pixel Sharp Memory LCD (LS013B4DN04)
  • Battery: CR2025 160mAh coin cell


  • The ATmega is in Sleep mode for most of the time and only runs once a minute to update the time or if a button is pressed. This reduces the current consumption to 2uA. Sady the display needs a certain pulse every second, which requires a complicated additional circuit. Because of this the current consumption is around 20uA. This still makes for around half a year of battery life.
  • User Interface controllable with three side buttons. Buttons are 3D-printed and activate switches on the PCB
  • Tells time, date, temperature and battery voltage on the main screen. No additional temperature sensor is needed, because the DS3231 already has one integrated for temperature compensation.
  • Stopwatch
  • Flappy Bird clone (“That would have been cool in 2013”)
  • The case consists of four 3D-printed parts. It has a thickness of only 10.8mm, which is thinner than the Apple Watch. Unfortunately it lacks screen protection.
  • Fits any 22mm Watchband

For more detail: Chronio – Low power Arduino based (smart)watch

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