Friday, April 29, 2022

IOT Dot Matrix Clock

Dot Matrix Clock

IOT Dot Matrix Clock / Dot Matrix Display  (DMC) (DMD)

  • An accurate clock for displaying time (Hours/second) and date would be a nice creation.
  • Added advantage would be to have it connected on the internet and splashes messages to it.
  • A WIFI based solution would be much better for easy access to the home/network ecosystem

  • Using an accurate RTC like DS3231 and Wifi chip ESP8266, a PCB was fabricated.
  • Also there was a need to make a good case to host the electronics.
  • Acrylic case making is cheaper as compared to 3d printing.
  • Found an enterprising acrylic fabricator who made an amazing case.  The power supply was embedded in the back of the case so it could be directly plugged into the wall socket or the ESP8266's USB power connector provided for at the side of the casing.
  • Uses the MajicDesigns MD_MAX72XX library from here MajicDesigns MAX72XX library
  • The fabricated DMC looks as follows:

Mains Enabled Clock



  • The DMC can be run off either AC mains or an external battery.
  • It keeps accurate time and also shows scrolling date.
  • The clock also has switch at the side to directly interact with the device in case Net access is not available.
  • The DMC comes up in Hotspot/AP mode and runs a Webserver internally. Using a browser after connecting to the AP, one can set the DMC to connect to an existing home AP with configuration options for
    • Network Name
    • Password
    • Update Server (for OTA updates)
    • Manual Update Option
    • Set Time on the RTC
    • Mechanism to display custom message (scrolled a few times a minute)
Firmware Update over the Network

  • Custom Messages via web URL can be sent to the display over the network as in the below example