7 Segment display Multiplexing with 74hc595 Shift Register Using Arduino

Overview

In this Arduino tutorial, we will how to multiplexing seven segment display with a 74hc595 shift register. A single digit display shows 0 to 9 decimal number. Ofen we need to display two, three, four or more digit decimal number, but the problem is lack of I/O (input/output) pins in the MCUs. To solve this problem we need for multiplexing. Here we will also use a 74hc595 shift register.

You can watch the following video below:-

Components Required

The following component needed for this tutorial

• Arduino Uno

• 2 Common anode 7 segment display

• 74hc595 shift register

• 220-ohm resistor

• Breadboard

• Some jumper wire

Pin Configuration

The following figure shows the common anode 7 segment display pinout. It has the total of 10 pins in which pin 3,8 common pin, pin 5 is DP and remaining pins are a,b,c,d,e,f,g.

Fig: Common anode 7 segment display pinout

Shift register 74hc595 pinout given below diagram:-

Fig: 74hc595 pinout

Circuit Schematic

The following figure shows the 7 segment display multiplexing with 74hc595 shift register using Arduino.

Fig: 7 Segment display multiplexing

Circuit Description

The shift register has 16 pins in which 7 output pins will connect with 7 segment LEDs pin. The shift register Vcc pin 16 and MR pin 10 will connect to +5V.  The ground pin 8 and output enable pin 13 will goes to ground. Next, shift register clock, latch, and data pins are gradually 11,12 and 14 will connect to Arduino digital pin 2, 3 and 4 respectively. Seven segment display common pins will connect to Arduino digital pin 6 and 7 through the 220-ohm series resistor.   

7 segment display ----------------- 74hc595 shift register

Pin_7(Seg_a)    ---------------          Pin_15(Q_A)

Pin_6(Seg_b)    ---------------          Pin_1(Q_A)

Pin_4(Seg_c)     ---------------          Pin_2(Q_A)

Pin_2(Seg_d)     ---------------          Pin_3(Q_A)

Pin_1(Seg_e)     ---------------          Pin_4(Q_A)

Pin_10(Seg_f)     --------------         Pin_5(Q_A)

Pin_9(Seg_g)     --------------          Pin_6(Q_A)

Source Code

This is the source code of multiplexing given below:-

 int DS_14 = 2;  
 int STCP_12 = 3;  
 int SHCP_11 = 4;  
    
 int j = 0;  
    
 int digit1 = 5;  
 int digit2 = 6;  
    
 int Digit[10] = {64, 121, 36, 48, 25, 18, 2, 120, 0, 24};  
    
 void setup() {  
  pinMode(STCP_12, OUTPUT);  
  pinMode(DS_14, OUTPUT);  
  pinMode(SHCP_11, OUTPUT);  
  pinMode(digit1, OUTPUT);  
  pinMode(digit2, OUTPUT);  
    
 }  
    
 void loop() {  
    
  for (int i = 0; i <= 10; i++)  
  {  
   if (i == 10) {  
    i = 0;  
    j = j + 1;  
   }  
   if (j == 6) {  
    j = 0;  
   }  
   {  
    
    for (int m = 0; m < 65; m++)  
    {  
     display1();  
     digitalWrite(STCP_12, LOW);  
     shiftOut(DS_14, SHCP_11, MSBFIRST, Digit[i]);  
     digitalWrite(STCP_12, HIGH);  
     delay(5);  
    
     display2();  
     digitalWrite(STCP_12, LOW);  
     shiftOut(DS_14, SHCP_11, MSBFIRST, Digit[j]);  
     digitalWrite(STCP_12, HIGH);  
     delay(5);  
    }  
   }  
  }  
 }  
    
 void display1()  
 {  
  digitalWrite(digit1, 1);  
  digitalWrite(digit2, 0);  
 }  
 void display2()  
 {  
  digitalWrite(digit1, 0);  
  digitalWrite(digit2, 1);  
 }