Interfacing LED matrix to Arduino
Connecting many LEDs on a microcontroller can sometimes be a real hassle. Here you will see how easy it is to connect 80 LEDs to only 8+2 microcontroller pins.
In this project, decimal counter chip CD4017 is used which is controlled with only two pins: clock and reset. Clock pin will "shift" the ON state of outputs from 1 through 10, while reset pin resets state to first output. This counter is used to address 10 rows on a display, while 8 columns (10x8) are controlled directly from a microcontroller which in this case is Arduino. Outputs of decimal counter are amplified with NPN transistors as seen in the schematics. Source code is available for download on project page.
[ Source: Syst3mX ]