Interfacing DOT MATRIX ARRAY with Arduino

Who doesn’t like Dot matrix displays!!! A blast from the past, that still brings the charm. Dot matrix LEDs are very popular means of displaying information as it allows both static and animated text as well as images. You might have noticed them at some public domains, such as advertisements, display pricing, along side the highways, petrol pumps etc. Here we will begin with a single monochrome 5×7 dot matrix display.

About LED dot matrix

Led matrix is an array of multiple LEDs arranged in a row by column order. Arrangement of the LEDs in the matrix pattern is made in either of the two ways – row anode – column cathode or row cathode – column anode. The matrix pattern minimizes the number of pins required to drive them. In this sample project 35 LEDs are controlled using a combination of 12 pins. Desired character or graphics can be displayed by switching ON /OFF  a desired configuration of LED’s, the perfection is (depends) on the number of LEDs on dot matrix. To light up an LED make corresponding cathode low and anode high. The quick scanning of row and column makes the data visible to our eyes, i.e. persistence of vision.

Hardware connection

 A minimum of 12 pins are required to wire up the dot matrix with an Arduino board, rows use 7 pins while columns need 5 pins. The rows are driven by pin1 through pin7 and the columns are driven by pin8 through pin12 of Arduino.

Rows
R0   →   1
R1   →   2
R2   →   3
R3   →   4
R4   →   5
R5   →   6
R6   →   7

Columns
C0   →   8
C1   →   9
C2   →  10
C3   →  11
C4   →  12

Example Code

Note: The logic levels to load the row and column to turn on LEDs depends on your display. The sample code is written for matrix with row cathode – column anode i.e, row=0 and column=1 turns the led on.

Some displays come with rows anode and columns cathode, i.e, row=1 and column=0 turns the led on. Make sure your program compatible with your display.

 

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