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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 SSD– There are mainly two types of SSD 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 SSD 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 to program this 8 pin to display our number on SSD. In following table, we convert this 8 pin’s 8 bit binary data into hex code and shows the hex code of displaying digits below.
| 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- SSD is widely use in digital clocks, pricing menu at petrol pump, in metros and electronics meters as shown above.
1.Circuit Diagram of COMMON CATHOD 7 SEGMENT Interfacing With PIC18F458
1. Program of 0 To 9 counter on CATHODE 7 SEGMENT INTERFACING With PIC18F458
/******************************************************
www.firmcodes.com
DEVELOPED BY:- FIRMWARE DEVELOPER
WHAT PROGRAM DO:- BLINK LEDs ON PORT2
******************************************************/
/* header file used in this program is already included in software microC pro for pic*/
void delay(); // for delay
void main() // start of main function
{
TRISC=0X00;
while(1) // undefined loop
{
PORTC= 0x3f;
delay(); //calling of delay function
PORTC=0x06;
delay(); //calling of delay function
PORTC=0x5b;
delay(); //calling of delay function
PORTC=0x4f;
delay(); //calling of delay function
PORTC=0x66;
delay(); //calling of delay function
PORTC=0x6d;
delay(); //calling of delay function
PORTC=0x7d;
delay(); //calling of delay function
PORTC=0x07;
delay(); //calling of delay function
PORTC=0x7f;
delay(); //calling of delay function
PORTC=0x6f;
delay(); //calling of delay function
}
}
void delay() // for delay
{
unsigned int i,j;
for(i=0;i<100;i++)
for(j=0;j<1000;j++);
}
PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com)
_____________________________________________________________________________________________________
2. Program of 000 To 999 counter on CATHODE 7 SEGMENT INTERFACING With PIC18F458
/******************************************************
www.firmcodes.com
DEVELOPED BY:- FIRMWARE DEVELOPER
WHAT PROGRAM DO:- 3 SEVEN SEGMENT ARE USED TO COUNT FROM 000 TO 999 USING ATMEGA16
******************************************************/
/* header file used in this program is already included in software microC pro for pic*/
#define c PORTB //access portc as a variable name led
#define b PORTC //access portc as a variable name led
#define a PORTD //access portc as a variable name led
void delay(); // delay
void main()
{
int ar[]={ 0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f }; // data of common cathode
unsigned int i,j,k; // initilize as a variable
TRISB=TRISC=TRISD=0X00; // make b,c,d port as output
while(1)
{
for(i=0;i<10;i++)
{
a=ar[i]; // data of ar[i] goes to port P1
for(j=0;j<10;j++)
{
b=ar[j]; // data of ar[i] goes to port P2
for(k=0;k<10;k++)
{
c=ar[k]; // data of ar[i] goes to port P3
delay();
}
}
}
}
}
void delay() // delay
{
int m,n;
for(m=0;m<500;m++)
for(n=0;n<153;n++);
}
PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com)
Content for the tab VIDEO