Matrix LED displays are quite commonly used these days. You can find them in elevators, various electronic equipment, or the running signs at airports and shopping molls. Indeed the charcter LCDs contain a collection of 5x7 matrix LCD dots. It is therefore a very good excersise to program a microcontroller to use these displays. This diplay board, contains a 5x7 LED matrix module, coupled with some additional circuitry. The LED matrix has 7 rows and 5 columns. The are connected in such a way that the entire column is connected to microcontroller output pins, which should provide a logical 1, or 5V signal on each line to illuminate the corresponding LED. Columns are selecteted sequenually by 4017 decade counter. the board will therefore require 7 outputs for rows from microcontroller, and 1 line for triggering the decade counter to select next column, and 1 line to reset the decade counter when all the 5 columns have been scanned. This module will use Persistance of Vision (POV) to display various characters, letters, and animations. It will be a lot of fun, programming for this module. Experience gained in this can be used to make even bigger, and more robust display boards. This board can be used with any microcontroller project, which can spare 9 I/O lines. In addition the board contains two push switches, and 1 Pizo buzzer, which can also be programmed through your microcontroller. This module was taken from talking electronics, most of the project is same, except we have removed the PIC16F84 microcontroller, and made it a universal module for use with existing microcontroller boards.
