Interfacing LED dot matrix display to 8051 Microcontroller

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LED dot matrix display:

An LED dot matrix display consists of a matrix of  LED’s arranged in a rectangular configuration. The desired character or graphics can be displayed by switching ON /OFF  a desired configuration of LED’s. Common display configurations available are 7×5, 8×8, 7×15, etc. LED dot matrix can be used in simple display applications where the resolution is not a big concern.  The figure below shows the arrangement of LEDs in a typical 7×5 dot matrix display.

http://www.circuitstoday.com/wp-content/uploads/2013/11/led-dot-matrix-display.png

http://www.circuitstoday.com/wp-content/uploads/2013/11/dot-matrix-display-logic.png

http://www.circuitstoday.com/wp-content/uploads/2013/11/led-dotmatrix-display.png

In the above diagram you can see that only one LED in a row will be ON at a time but any number of  LEDs in a column can be ON at a time.  That means the microcontroller’s port pin can directly drive a row but it requires  additional circuit for driving the column lines.  The circuit diagram for interfacing dot matrix display and 8051 microcontroller is shown below.

                                                                         Display ‘A’ on 5×7 LED Dot Matrix

Keil C Program:

#include<reg51.h>

unsigned int Col[5]= {0xfe,0xfd,0xfb,0xf7,0xef};
unsigned int Row[5]={0xfe,0x11,0x11,0x11,0xfe};

void delay (unsigned int x)
{
unsigned int k,m;
for (k = 0;k<x;k++)
{
for(m=0;m<500;m++);
}

}
void main()

{

unsigned int d;
while(1)
{

for(d=0;d<5;d++)

{

P2=Col[d];
P3=Row[d];
delay(1);
}

}
}

 

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