Decimal-time watch face for SQFMI's Watchy


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You can also use your local clone with git send-email.

#CALCULATEUR: A decimal watch face for SQFMI's Watchy


In contrast to common clocks, Calculateur tells the usable time ahead, mapping each day to 1000 decimal minutes, counting down.

Visit https://jochen.link/experiments/calculateur.html for more information and to check out the web version or download the Chrome extension.

#CHECK OUT WATCHY: Fully Open Source E-Paper Watch:

Please visit https://watchy.sqfmi.com for documentation, hardware design files, and more!

Calculateur is to 99.9% the fantastic work of SQFMI with some minor, messy modifications to the original Watchy library by me. For Calculateur to function it was necessary to use DS3232RTC Alarm1, waking it up only every 86.4 seconds.

Besides enabling the actual watch face, it'll also keep your Watchy running for longer :)


  1. In the Arduino IDE Boards Manager, install support for the ESP32. You can find instructions here: https://github.com/espressif/arduino-esp32/blob/master/docs/arduino-ide/boards_manager.md
  2. Install the original Watchy library (search for Watchy in the library manager), and any other depdencies when prompted!
  3. Compile & Upload with these board settings:
    • Board: "ESP32 DEv Module"
    • Partition Scheme: "Minimal SPIFFS"
    • All other Settings: leave to default

If you don't install the original Watchy library you'll need following dependencies:

  • Adafruit_BusIO
  • Adafruit_GFX_Library
  • Arduino_JSON
  • DS3232RTC
  • GxEPD2
  • Time
  • Ultrasonic
  • WiFiManager

PS: sorry for the mess :)