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Micro Word Clock v2


A tiny replica of the famous Word Clock, using only an ATmega microcontroller, a DS1307 Real Time Clock and a few passive components to display the time on an 8x8 LED matrix. The letters have been printed onto a transparent sheet and glued over the LEDs to produce a readable time. See the YouTube video here.

Directory structure

  • MicroWordClock2-Arduino contains the firmware, including pin definitions for the LED matrix and location of the words in each language.
  • EAGLE contains the schematic and PCB design files for the proejct.
  • Graphics contains the design for the transparency sheet to place over the LED matrix to form the words, designed in Inkscape. Contributions in more languages are welcome!

Bill of Materials

Part name Package size Reichelt part number
IC1 ATmega328P-AU TQFP-32 ATMEGA 328P-AU
IC2 DS1307Z+ SO-8 DS 1307Z
C1 220nF ceramic 2012 metric / 0805 imperial X7R-G0805 0,22µ
C2 2.2uF tantalum 3528 metric / B-case SMD TAN.2,2/20
S1 SMD push button 6.2x6.5mm TASTER 9314
XTAL 32.768 kHz crystal 3216 metric / 1206 imperial 32,768 CC7V-12,5
LED matrix 8x8 matrix 20x20mm GYXM-788ASR* (DealExtreme)
PCB 20x20mm OshPark
* Probably any LED matrix labeled 788 should work.

You will require an In-System Programmer (ISP) to write the firmware onto the microcontroller.

Burning the bootloader and uploading the sketch

Please read these two tutorials if you are unfamiliar with burning a bootloader:

The required procedure is the one described as "AVR on a breadboard" and "Minimal circuit", respectively, as there is no external crystal attached to the microcontroller.

Please download Carlos Rodrigues' Barebones ATmega Chips board configuration file: (instructions inside)

The ICSP header on the Micro Word Clock PCB is the standard layout described here (Fig. 2).


Carl Monk has built his own version using a Unicorn HAT.

quistoph has made a Dutch layout.

Tanguy Rewers independently came up with an alternative Dutch layout (labeled as dutch2).

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This project (both software and hardware) is published under a Creative Commons BY-SA 3.0 License.


Displaying the time in 8x8 pixels







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