Introduction
Online Simulation
Description
Pin Definitions
Display Characters
Setup Function
Loop Function
DisplayNumber Function
ShiftOut Function

Published November 8, 2024

Arduino-Controlled Dual 7-Segment LED Counters

Unlock creativity with Arduino-Controlled Dual 7-Segment LED Counters! Perfect for projects, displays, and learning electronics effortlessly

BeginnerFull instructions provided180

Things used in this project

Hardware components

Arduino UNO

Texas Instruments Shift Register- Serial to Parallel

7 Segment LED Display, InfoVue

Software apps and online services

PCBX Online Simulation

Story

Introduction

A simple example of how to use Arduino and two 8-bit shift registers to control two 7-segment LED displays to show numbers. By cycling through the numbers 0 to 9, you can observe the digits changing on the displays.

Online Simulation

Description

Pin Definitions

The code begins by defining the pins connected to the shift registers:

data Pin (Pin A5): This is the serial data input pin for the shift register.

clock Pin (Pin A4): This is the clock input pin for the shift register.

reset Pin (Pin A3): This is the reset pin for the shift register, used to clear the register before sending new data.

Display Characters

The numbers array defines the hexadecimal codes for the digits 0 through 9 for a common cathode 7-segment display. These codes indicate which segments should be lit to display each digit.

Setup Function

In the setup function, all defined pins are set to output mode.

Loop Function

The loop function contains an infinite loop called the displayNumber function, which displays two digits on the 7-segment displays, with each digit being displayed for 1 second (1000 milliseconds).

DisplayNumber Function

The display Number function takes two parameters, num1, and num2, which are the digits to be displayed on the two 7-segment displays. The function first resets the shift register by pulling the reset pin low and then high. It then sends the data for each digit to the corresponding shift register and locks it in with the latch pin.

ShiftOut Function

The shift-out function is used to send a byte of data to the shift register. It loops through 8 times, sending each bit of the data byte to the data pin and toggling the clock pin to shift the data.

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Code

Arduino-Controlled Dual 7-Segment LED Counters

// Define pins
const int dataPin = A5;    // The D1 pin of the shift register is connected to pin A5 of the Arduino
const int clockPin = A4;   // The clock input pin of the shift register is connected to pin A4 of the Arduino
const int resetPin = A3;   // The reset pin of the shift register is connected to pin A3 of the Arduino

// Common cathode 7-segment display characters
byte numbers[] = {
    0x3F, // 0
    0x06, // 1
    0x5B, // 2
    0x4F, // 3
    0x66, // 4
    0x6D, // 5
    0x7D, // 6
    0x07, // 7
    0x7F, // 8
    0x6F  // 9
};

void setup() {
    pinMode(dataPin, OUTPUT);
    pinMode(clockPin, OUTPUT);
    pinMode(resetPin, OUTPUT);
}

void loop() {
    for (int i = 0; i < 10; i++) {
        displayNumber(i, (i + 1) % 10);
        delay(1000);
    }
}

void displayNumber(int num1, int num2) {
    digitalWrite(resetPin, LOW); // Reset shift register
    digitalWrite(resetPin, HIGH);
    
    //Send data to the first 7-segment display
    shiftOut(dataPin, clockPin, MSBFIRST, numbers[num1]);
    
    // Send data to the second 7-segment display
    shiftOut(dataPin, clockPin, MSBFIRST, numbers[num2]);
}

void shiftOut(int value) {
    for (int i = 0; i < 8; i++) {
        digitalWrite(dataPin, (value & (1 << (7 - i))) ? HIGH : LOW);
        digitalWrite(clockPin, HIGH);
        digitalWrite(clockPin, LOW);
    }
}

Credits

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Arduino-Controlled Dual 7-Segment LED Counters