Seven Segment Display Basics and How to use it with Arduino

Learn how to interface a Seven Segment Display with Arduino in this comprehensive guide. Seven segment displays are widely used for numeric display tasks in various electronic devices. This tutorial will walk you through the process of connecting and controlling a Seven Segment Display with an Arduino board.

Components Needed:

• Seven Segment Display
• Arduino board
• Breadboard
• Jumper wires
• Current limiting resistors (e.g., 330 ohms)
• Computer with Arduino IDE installed.

And here is a small simulation showing the Seven Segment Interface. The Arduino will count from 0 to 9 and repeat. The value will be displayed on the Seven Segment display. Seven-segment displays are available in various sizes and colours. They are available from 0.28 inches to 18 inches, and even bigger sizes are available for industrial usage. The most commonly used display size is 0.56 inches.

Seven Segment Display Pinout

As the name suggests, the seven-segment display consists of seven LEDs, which are arranged in a particular order to form the digit eight. And most common modules will come with an additional LED to indicate the decimal point. This will be useful when using multiple display modules to display a decimal number. Each one of these LEDs are arranged in a specific order as a segment and one of its pins is being brought out of the plastic package. The other LED pins are connected together and wired to form a common pin.Before diving into interfacing a Seven Segment Display with Arduino, it's crucial to understand its basic principles. Seven segment displays are composed of seven individual LED segments arranged in a specific pattern to display numeric digits (0-9) and sometimes alphabets. These displays are categorized into two types: Common Cathode (CC) and Common Anode (CA). In a Common Cathode display, all cathodes of the LEDs are connected together and linked to the ground, while in a Common Anode display, all anodes are connected together and linked to the positive voltage supply. By controlling the activation of each LED segment, we can illuminate specific combinations to display desired numbers or characters.

Common Cathode Displays

In a Common Cathode (CC) display, all the cathodes of the LEDs are connected together to the common pin. This common pin is then connected to the ground rail of the circuit. The individual LEDs can be activated by applying a high pulse or a logic 1 signal to the corresponding pin.

Common Anode Displays

In a Common Anode (CA) display, all the anodes of the LEDs are connected together to the common pin. This common pin is then connected to the positive rail of the circuit. The individual LEDs can be activated by applying a low pulse or a logic 0 signal to the corresponding pin.

Connecting Seven Segment Display with Arduino

Now let’s see how we can drive a seven-segment display with an Arduino. For that let’s start by placing the display module on a breadboard with the decimal point facing downwards. Then wire up each pin as per the connection diagram below. In this tutorial, we will be using a Common Cathode display.

Connect either of the common pins (seven-segment pin 3 or 8) to the ground. And connect the rest of the pins to D2 to D9 of the Arduino through a current limiting resistor, as per the connection diagram. Just like driving an LED, it is preferable to use these current limiting resistors to increase the display life. Choose these values depending on the display colour and size. Here we will be using a 330 ohms resistor which will provide around 10mA current for the LEDs.

And here is the actual circuit.

Github Link for Code for Circuit: https://github.com/Circuit-Digest/Basic-Arduino-Tutorials-for-Beginners-/tree/main/Interfacing%20Seven%20Segment%20Display%20with%20Arduino

Projects Featuring Seven Segment Displays:

• Guide and code for connecting Seven Segment Display to Raspberry Pi.
• Build a digital clock using Arduino and four 7-segment displays.
• Create a digital counter with 555 Timer IC.

#include "SevSeg.h"
SevSeg sevseg;
void setup()
{
  //Set to 1 for single-digit display
  byte numDigits = 1;

  //defines common pins while using multi-digit display. Left for single digit display
  byte digitPins[] = {};

  //Defines Arduino pin connections in order: A, B, C, D, E, F, G, DP
  byte segmentPins[] = {9,8, 7, 6, 5, 4, 3, 2};

  byte displayType = COMMON_CATHODE; //Use COMMON_ANODE for Common Anode display

  bool resistorsOnSegments = true; //‘false’ if resistors are connected to common pin

  //Initialize sevseg object. Use COMMON_ANODE instead of COMMON_CATHODE for CA display
  sevseg.begin(displayType, numDigits, digitPins, segmentPins, resistorsOnSegments);

  sevseg.setBrightness(90);
}

void loop()
{ 
   //Display numbers 0-9 with 1 seconds delay
   for(int i = 0; i <= 10; i++)
   {
     if (i == 10)
{
 i = 0;
}
     sevseg.setNumber(i);
     sevseg.refreshDisplay(); 
     delay(1000);
   }
}