Friday, January 30, 2015

Life Clock - Redo

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I created the Life Clock in 2008. Originally it was a "3 board stack"  with one being ATmega, RTC, and EEPROM and another with the MAX7221 chips that the bicolored matrix plugs into.

I really liked how it came out, but I thought I'd update it and add some features.

During that process I discovered a great little bicolor matrix kit from Jollifactory which provides the led matrix and a driver board. It's well priced, and really simplifies construction.

The matrix kit is available on Tindie here and shown below. It's  especially nice that multiple matrices can be chained together to make a larger display. If you're interested in led matrix projects it's a good way to go.

I then made a new PCB to hold the ATmega, RTC, EEPROM, piezo and IR sensor. It stacks on one of the Jollifactory matrix boards and provides a complete Life Clock. More matrices can be added if desired. The PCB looks like this:

A kit is now available here and also on Tindie .

Below is a video showing the current LifeClock software on 1-3 Jollifactory matrices.

The new software supports from 1 to at least, 4 Jollifactory matrices. The original LedControl library was modified to use hardware SPI instead of shiftout. This much faster lib is necessary if multiple matrices are used. As shown in the video, the LifeClock now has the following features:
  • Displays the time, hourly chime, alarm, and auto DST set.
  • Plays Conway's Game of Life in 3 colors.
  • Shows the phase of the moon, days to next full moon, and name of full moon.
  • Displays the time of sunrise and sunset.
  • Displays reminders for birthdays, etc.
  • Time setting controlled by a NEC mini-remote.
  • Optionally, a GPS can be added to sync the time automatically.
  • Fonts, messages, and reminders stored in external EEPROM.
[7/1/15 update] A more affordable "mini" version of the Life Clock is now available here.  It uses smaller single color matrix displays .


  1. nice projects
    do you know how to store string in EEPROM?

    1. One char at a time!
      Google "arduino storing a string in eeprom" for the best answer.

  2. Thank you.
    Just added a mini version of the Life Clock. Single color matrix. See