8051 Interface – 7 Segment Display

This tutorial will discuss about 8051 Interface – 7 Segment Display. 7-Seg display is the most basic electronic display. It consists of eight LEDs which are associated in a sequence manner to display digits from 0 to 9 when proper combinations of LEDs are switched on. A 7-segment display uses seven LEDs to display digits from 0 to 9 and the 8th LED is used for dot. A typical seven-segment look likes as shown in the figure below. The 7-segment displays are used in several systems to display the numeric information. They can display one digit at a time. Thus the number of segments used depends on the number of digits to display. Here the digits 0 to 9 are displayed continuously at a predefined time delay.

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Use of 7 Segment Display

• Numeric Display: Shows numbers (0-9) and some letters (A-F).
• Segment Control: Each segment can individually controlled.
• Connection: Requires connection to microcontroller GPIO pins.
• Display Logic: Determine which segments to illuminate for each digit.
• Multiplexing: Can display multiple digits by rapidly switching between them.
• Example Usage: Digital clocks, timers, counters, and temperature displays.

Required software

• Windows machine (Any Version)
• Keil IDE  tool for 8051
• ProgISP v1.72

Required components and Programmer

• 1x AT89S51 Controller
• 1x 4Mhz Crystal
• 2x 22pf capacitor
• ISP AVR USB programmer
• 7 Seg Display

Circuit Diagram

C code

•  See on GitHub : https://github.com/ArunEworld/Embedded/blob/master/8051-MCU/8051-Interface/8051-Interface-7-Segment-Display.c

#include<reg51.h>

void delay(int k) //delay function
{
int i,j;
for(i=0;i<k;i++)
  for(j=0;j<1275;j++);
}
void main()
{
    unsigned char i;
    unsigned char arr[10]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x67};
    P2=0x00;    
    while(1)
    {
        for(i=0;i<10;i++)
        {
            P2=arr[i];
            delay(100);
        }
        
    }
}

---

Assembly Code (ASM)

•  See on GitHub : https://github.com/ArunEworld/Embedded/blob/master/8051-MCU/8051-Interface/8051-Interface-7-Segment-Display.asm

//See more on : http://www.ArunEworld.com

ORG 000H //initial starting address
START: MOV A,#00001001B // initial value of accumulator
MOV B,A
MOV R0,#0AH //Register R0 initialized as counter which counts from 10 to 0
LABEL: MOV A,B
INC A
MOV B,A
MOVC A,@A+PC // adds the byte in A to the program counters address
MOV P1,A
ACALL DELAY // calls the delay of the timer
DEC R0//Counter R0 decremented by 1
MOV A,R0 // R0 moved to accumulator to check if it is zero in next instruction.
JZ START //Checks accumulator for zero and jumps to START. Done to check if counting has been finished.
SJMP LABEL
DB 3FH // digit drive pattern for 0
DB 06H // digit drive pattern for 1
DB 5BH // digit drive pattern for 2
DB 4FH // digit drive pattern for 3
DB 66H // digit drive pattern for 4
DB 6DH // digit drive pattern for 5
DB 7DH // digit drive pattern for 6
DB 07H // digit drive pattern for 7
DB 7FH // digit drive pattern for 8
DB 6FH // digit drive pattern for 9
DELAY: MOV R4,#05H // subroutine for delay
WAIT1: MOV R3,#00H
WAIT2: MOV R2,#00H
WAIT3: DJNZ R2,WAIT3
DJNZ R3,WAIT2
DJNZ R4,WAIT1
RET
END

NEXT

8051 – Introduction

8051 – Program Methods

8051 – Flash HEX into 8051

8051 – USB ISP Programmer

8051 – Simulators

8051 Interface

8051 Interface – LED

8051 Interface – LCD

8051 Interface – 7 Segment

8051 Interface – Keypad

8051 Interface – Servo

8051 Protocol Interface

8051 – UART Bit banking

8051 – I2C Bit banking (Add Soon)

8051 Tutorials

8051 – 10Khz Square Wave

Others

8051 – Interview Questions