Voice Controlled LED Array Project

This project shows how to build an array of 120 LEDs how one microcontrollers controls them, and how a PC was used to communicate with them.

The row-column addressing is used by the project where several LEDs are being controlled without having one wire going to each one. The ATmega168 microcontroller can handle the increasing number of LEDs since the diodes only conduct in one direction. There are also some schemes that can be used to control even more LEDs but part of the tradeoff is that the LEDs would be ON for a shorter amount of time, making them less bright.

From the 120 LEDs wiring scheme, each of the 12 column wires and 5 row wires goes to an I/O pin of the microcontroller. The pin can be put in one of the three states by the software running on the chip. The LED will light up by allowing the current to flow if a path from HIGH to LOW exists across any LED in the forward direction.

The row-column addressing is an extremely common was of reducing the pin count of systems which allows for simpler wiring and cheaper parts.