As stated above, this is a software rendition of a microprocessor based clock display that I developed for my own use. The GUI version of the clock display has been written in several environments/languages so far:
- using a very old (16 bit) version of the MS compiler
- as a Java applet
- in PHP using a set of 12 images
The project was the first time that I had a reason to use blue LEDs. These fairly expensive devices (about 10 times the price of a red LED, but dropping) enable the manufacture of LED RGB displays, however at the time I started the project, single RGB LED packages were essentially unobtainable. So I used a mechanical arrangement whereby a single blue LED was shone through the back of a red/green part, creating a composite device. The story of the development is in the October 2003 issue of Circuit Cellar magazine (issue #159 ).
Since I wrote the article, Digi-Key started selling Lumex devices such as their part number 67-1820-1-ND (said to be Lumex part # SML-LX2832SISUGSBC, but the best fit part number on the manufacturer's site is SML-LX2832SRSGSBTR) for near $2.50 US. These little devices are amazing. I've tried them in a version of the clock, but I can't find a Red/Green device to match (package and wavelengths) from the same source.
The firmware for the actual hardware device was written in assembler to run on an MC68HC908JL3. See the Circuit Cellar article.