Description
It’s an example project of 7 segment display interfacing to microcontroller 8051.
Diagram
Detail
This project describes how can we connect 7 segment display to 8051 microcontroller. Similarly it can be connected to any other microcontroller like PIC or AVR with modifications in code. Counting from 0 to 9 is displayed on it after some delay. This project also describes how to use 8051 port pins for output and LED drive.
How 7 Segment Works
7 segment display consists of 7 segments and a dot. Actually each segment and dot are LEDs (Light Emitting Diodes). Each segment including dot are total 8 LEDs.
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Light Emitting Diode like an ordinary diode passes current in one direction (forward biased) and block in other (reverse biased) direction. Each LED has 2 pins one for anode and other for cathode. In common anode all anode terminals are connected together to form a common connection and remaining 8 cathodes are provided for negative side supply of individual LED. We connect common wire with positive supply and provide negative supply to appropriate LED segments to switch on and make a specific pattern on the whole display. In common cathode display all pins are opposite to common anode. All cathode terminals are connected to form a common connection and all other 8 pins are anodes. Pin diagram of commonly used seven segment display are given in above figure.
Code
///////////////////////////////////////////////////////////
// Company : Micro Digital //
// DAV College Road //
// Rawalpindi, //
// Pakistan. //
// Programmed By : Rashid Mehmood //
// Project Name : 8051 To Seven Segment Display //
// Crystal : 24.000000 MHz //
// Microcontroller : AT89C2051-C51-C52-C55-S2051-S51-S52 //
///////////////////////////////////////////////////////////
// Start of code.
// Header file for AT89x051 microcontrollers.
#include <AT89x051.h>
#define SSeg P1
code const unsigned char RealDigit[10] = {
0x40, 0x79, 0x24,
0x30, 0x19, 0x12,
0x02, 0x78, 0x00,
0x10
};
void delay(unsigned int del)
{
// Wait until del is greater zero.
while(del --);
}
// Displays value (0 to 9) on seven
// segment display.
void Display(unsigned char Value)
{
if(Value < 10)
SSeg = RealDigit[Value];
}
void main()
{
unsigned char Value = 0;
while(1)
{
for(Value = 0; Value < 10; Value ++)
{
Display(Value);
delay(30000); // Calibrated delay.
}
}
}
// End of code.
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