05 Nov

Word Clock – Build Log Part 1

My friend and I have been building a word clock for some time now. It all was all inspired when he bought this beautiful watch:

Word Clock Watch

This watch has inspired us to make our own

As a wrist watch is somewhat difficult, to say the least, to make we decided to make a wall clock. One of the major problems we faced when thinking about how to make this watch was the sheer number of outputs required! 114 not including inputs to set the time! The standard Arduino micro-controller has 14 digital IO. Not going to cut it. Brainstorming ideas we came up with a few:

  • Getting two Arduino Megas which communicate together – seemed like a bit of overkill
  • Chrlieplexing – a sexy method, on investigation we found that it might dim the LEDs too much as only one is turned on at a time so the light is dimmed by the number of LEDs on.
  • Multiplexing – Looked good in theory but the number of 8 bit multiplexers we would need came to 15! Didn’t look like a cheap alternative to me!

So, in the end, we settled for a more simplistic model instead, say hello to what would become version 1:

Word Clock Simple
Version 1, a more simple approach to a word clock

As you can see, the words are grouped, we lose control of each letter but reduce our IO so now we only need 3 x 8bit shift registers! #WINNING

We have gotten inspiration from the many word clocks out there, namely this one.

I’ll break the next few posts into the following:

  1. Mechanical construction – Oh frame where art thou
  2. Electrical construction – Two weeks is a long time to wait for a prototype
  3. Software compilation – If two bits walk into a bar…

Thanks for reading!