SEVEN SEGMENT DISPLAY INTERFACING WITH ARDUINO | GEMLABs | Embedded product development platform | Internet of Things (IoT) Courses | Advanced IoT Training | IoT Certification | IoT training in chennai | Best IoT Training Center | IoT Design and Development | Best Embedded Training Center in Chennai | Robotics Engineering | IOT Systems | Embedded Systems | PCB | Aurdino

Synopsis

In this tutorial we are going to interface a seven segment display with Arduino. Here we are using Atmega328p microcontroller instead of Arduino. The display counts from 0-9 and resets itself to zero.

A seven segment display got its name from the very fact that it got seven illuminating segments. Each of these has a LED (Light Emitting Diode), hence the lighting. The LEDs are so fabricated that lighting of each LED is contained to its own segment. The important thing to notice here that the LEDs in any seven segment display are arranged in common anode mode (common positive) or common cathode mode (common negative).

Description

The circuit connection of LEDs in common cathode and common anode is shown in below figure.

Here one can observe that, in common cathode the negative terminals of every LED is connected together and brought out as GND. In common anode the positive of every LED is connected together and brought out as VCC. These common cathode and common anode come in very handy while multiplexing several cells together.

To display a particular number, you turn on the individual segments as shown in the table below.

In general, common anode displays are more popular as many logic circuits can sink more current than they can source. Also note that a common cathode display is not a direct replacement in a circuit for a common anode display and vice versa, as it is the same as connecting the LEDs in reverse position, and hence light emission will not take place.

Depending upon the decimal digit to be displayed, the particular set of LEDs is forward biased. For instance, to display the numerical digit 0, we will need to light up six of the LED segments corresponding to a, b, c, d, e and f. Thus the various digits from 0 through 9 can be displayed using a 7-segment display.

Proteus design for Seven Segment interfacing with Arduino

Orcad design for Seven Segment interfacing with Arduino

Seven Segment Interfacing with Arduino

/*  Name     : main.c
 *  Purpose  : Source code for Seven Segment Interfacing with Arduino.
 *  Author   : Gemicates
 *  Date     : 12-01-2018
 *  Website  : www.gemicates.org
 *  Revision : None
 */
#include "Arduino.h"

int disp_pin[7];                                                                 // array for a-g pins of 7-Segment display 

void define_segment_pins(int a, int b, int c, int d, int e, int f, int g)        // Assigns 7-segment display pins to board 
{  
  disp_pin[0] = a;
  disp_pin[1] = b;
  disp_pin[2] = c;
  disp_pin[3] = d;
  disp_pin[4] = e;
  disp_pin[5] = f;
  disp_pin[6] = g;
}

void display_number(int num)                                                     // Function for displaying number (0-9)
{
  switch(num)
  {
    case 0:
    digitalWrite(disp_pin[0], LOW);                                              // Drive disp_pin[0] to LOW 
    digitalWrite(disp_pin[1], LOW);                                              // Driving LOW turns on LED segment for common anode display 
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], LOW);
    digitalWrite(disp_pin[5], LOW);
    digitalWrite(disp_pin[6], HIGH); 
    break;
    case 1:
    digitalWrite(disp_pin[0], HIGH);                                             // Drive disp_pin[7] to HIGH
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], HIGH);                                             // Driving HIGH turns off LED segment for common anode display 
    digitalWrite(disp_pin[4], HIGH);
    digitalWrite(disp_pin[5], HIGH);
    digitalWrite(disp_pin[6], HIGH);
    break;
    case 2:
    digitalWrite(disp_pin[0], LOW);
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], HIGH);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], LOW);
    digitalWrite(disp_pin[5], HIGH);
    digitalWrite(disp_pin[6], LOW);
    break;
    case 3:
    digitalWrite(disp_pin[0], LOW);
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], HIGH);
    digitalWrite(disp_pin[5], HIGH);
    digitalWrite(disp_pin[6], LOW);
    break;
    case 4:
    digitalWrite(disp_pin[0], HIGH);
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], HIGH);
    digitalWrite(disp_pin[4], HIGH);
    digitalWrite(disp_pin[5], LOW);
    digitalWrite(disp_pin[6], LOW);
    break;
    case 5:
    digitalWrite(disp_pin[0], LOW);
    digitalWrite(disp_pin[1], HIGH);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], HIGH);
    digitalWrite(disp_pin[5], LOW);
    digitalWrite(disp_pin[6], LOW);
    break;
    case 6:
    digitalWrite(disp_pin[0], LOW);
    digitalWrite(disp_pin[1], HIGH);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], LOW);
    digitalWrite(disp_pin[5], LOW);
    digitalWrite(disp_pin[6], LOW);
    break;
    case 7:
    digitalWrite(disp_pin[0], LOW);
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], HIGH);
    digitalWrite(disp_pin[4], HIGH);
    digitalWrite(disp_pin[5], HIGH);
    digitalWrite(disp_pin[6], HIGH);
    break;
    case 8:
    digitalWrite(disp_pin[0], LOW);
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], LOW);
    digitalWrite(disp_pin[5], LOW);
    digitalWrite(disp_pin[6], LOW);
    break;
    case 9:
    digitalWrite(disp_pin[0], LOW);
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], HIGH);
    digitalWrite(disp_pin[5], LOW);
    digitalWrite(disp_pin[6], LOW);
    break;
    default:
    digitalWrite(disp_pin[0], HIGH);
    digitalWrite(disp_pin[1], LOW);
    digitalWrite(disp_pin[2], LOW);
    digitalWrite(disp_pin[3], LOW);
    digitalWrite(disp_pin[4], LOW);
    digitalWrite(disp_pin[5], HIGH);
    digitalWrite(disp_pin[6], LOW);
    break;
  }
}

void setup() {
  pinMode(6, OUTPUT); 
  pinMode(7, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(12, OUTPUT);
  define_segment_pins(12,11,10,9,8,7,6);                                         // a-g segment pins to Arduino 
}

void loop() {
  while(1)
  {
    int i;
    for(i = 0; i<=9; i++)
    {
      display_number(i);
      delay(100);
    }
  }
}