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- What is 7 SEGMENT DISPLAY (SSD)? – A seven-segment display is a form of electronic display device for displaying decimal numbers (and some alphabets too). SSD may use a liquid crystal display (LCD), a light-emitting diode (LED) for each segment, or other light-generating or controlling techniques such as cold cathode gas discharge, vacuum fluorescent, incandescent filaments, and other.
- Types of 7 segment display– There are mainly two types of 7 segment dispaly available. In a simple LED package, typically all of the cathodes (negative terminals) or all of the anodes (positive terminals) of the segment LEDs are connected and brought out to a common pin; this is referred to as a “common cathode” or “common anode” device. Besides this, there is also a 7 segment display multiplexer is used called 2 digit, 3 digit and so on as you can see on photos.
- Operation – In a simple LED package common cathode SSD, there has 10 pin out of which 2 is ground and rest is LED segments . Particular LED segment is glow(ON) by giving logic ‘1’ to it and rests at logic ‘0’.
So we need program this 8 pin to display our number on 7 segment display . Following table shows the hex code of displaying digits.
| Digit | Hex code | A | B | C | D | E | F | G |
| 0 | 0x3F | 1 | 1 | 1 | 1 | 1 | 1 | 0 |
| 1 | 0x06 | 0 | 1 | 1 | 0 | 0 | 0 | 0 |
| 2 | 0x5B | 1 | 1 | 0 | 1 | 1 | 0 | 1 |
| 3 | 0x4F | 1 | 1 | 1 | 1 | 0 | 0 | 1 |
| 4 | 0x66 | 0 | 1 | 1 | 0 | 0 | 1 | 1 |
| 5 | 0x6D | 1 | 0 | 1 | 1 | 0 | 1 | 1 |
| 6 | 0x7D | 1 | 0 | 1 | 1 | 1 | 1 | 1 |
| 7 | 0x07 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
| 8 | 0x7F | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| 9 | 0x6F | 1 | 1 | 1 | 1 | 0 | 1 | 1 |
- Applications- 7 segment display is widely use in digital clocks, pricing menu at petrol pump, in metros and electronics meters as shown above.
1.Circuit Diagram of COMMON CATHODE SEVEN SEGMENT Display Interfacing With 8051
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1. Program of 0 To 9 counter on CATHODE SEVEN SEGMENT DISPLAY With ATmega16
/******************************************************
www.firmcodes.com
DEVELOPED BY:- FIRMWARE DEVELOPER
WHAT PROGRAM DO:- COUNTING 0 TO 9 ON 7 SEGMENT DIPLAY
******************************************************/
#include<avr/io.h>
#include<util/delay.h>
int ar[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};
void main()
{
unsigned int i;
DDRA=0XFF;
while(1)
{
for(i=0;i<10;i++)
{
PORTA=ar[i];
_delay_ms(300);
}
}
}
PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com)
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2. Program of 000 To 999 counter on CATHODE 7 SEGMENT DISPLAY With ATmega16
/******************************************************
www.firmcodes.com
DEVELOPED BY:- FIRMWARE DEVELOPER
WHAT PROGRAM DO:- COUNTING 000 TO 999 USING THREE 7 SEGMENT DISPLAY
******************************************************/
#include<avr/io.h>
#include<util/delay.h>
int ar[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};
void main()
{
unsigned int i,j,k; //// initilize as a variable
DDRA=0XFF;
DDRB=0XFF;
DDRC=0XFF;
while(1)
{
for(i=0;i<10;i++)
{
PORTA=ar[i]; // data of ar[i] goes to port P1
for(j=0;j<10;j++)
{
PORTB=ar[j]; // data of ar[i] goes to port P2
for(k=0;k<10;k++)
{
PORTC=ar[k]; // data of ar[i] goes to port P3
_delay_ms(300);
}
}
}
}
}
PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com)
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