Hans writes – “This LED Matrix Clock is a feasability study for a much larger project I am building for my employer, the intention was to prove to myself (and my employer!) that I am able to drive an LED matrix from a PC. This is the first project I have made which is driven by a PC. The clock uses 3 B64CDM8/B48CDM8 8×8 5mm LED Matrix modules from Nexus Machines, each having an onboard MAX7219 display driver chip. These require an SPI serial interface, which I by toggling pins of the host PC’s parallel port (printer port). The small software application which drives the displays is written in Delphi 5 and runs on Windows NT 4.” Link.
Build a LED matrix clock