The project uses (2) 5×7 LED Displays, so 10 columns and 7 rows for a total of 70 LEDs.Â The matrix works on the basis of scanning the display very quickly. The 4017 chip is used to switch between the columns. The way the 4017 chip works, is that when a signal is sent to a certain pin, 1 of 10 of the other pins is sequentially activated. The way the software works, is it tells the chip to switch columns, which sets one column high.
The software then makes the parallel port turn on the individual LEDs in that column needed. This is done very quickly, many times a second. It’s a fairly easy concept and it turned out the programming was easier than the author had initially anticipated.
And the great thing about this project is that it also comes with a font writer, which is basically a software written also by the author of the circuit to help him quickly design animations.
Computer Controlled LED Matrix: [Link]