Seven-Segment Display Mini Project

By Dasha Katkova

Seven-segment display wired on a breadboard

Project Snapshot

Shift register controlling a seven-segment display

I made this project to continue learning about shift registers. I used a seven-segment display to make it more challenging. I made two programs: counting up and a random number generator.

The materials I used are:

  • 74HC595 shift register
  • 1 LTS - 4301C 7 segment display
  • 8 220 Ω resistors
  • Arduino Nano microcontroller

Code

counting up and a random number generator

counting up

1 / 2 
#include <Arduino.h>

// 1. Tell the computer what pins the shift register is on
const int latchPin = 12; 
const int clockPin = 13; 
const int dataPin = 11;  

int time = 400;

const byte digitMap[] = {
  0b11110110, // 0
  0b10000100, // 1
  0b01101110, // 2
  0b11001110, // 3
  0b10011100, // 4
  0b11011010, // 5
  0b11111010, // 6
  0b10000110, // 7
  0b11111110, // 8
  0b11011110  // 9
};

void setup() {
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  delay(2000);
}



void displayNumber(int myNumber) {
  digitalWrite(latchPin, LOW);                                // 1. Open the shifter gate
  shiftOut(dataPin, clockPin, MSBFIRST, digitMap[myNumber]);  // 2. Push the raw bits out
  digitalWrite(latchPin, HIGH);                               // 3. Close the gate to update the screen
}

void loop() {
  for (int i = 0; i < 10; i++) {
    displayNumber(i);
    delay(time);
  }
}
#include <Arduino.h>

// 1. Tell the computer what pins the shift register is on
const int latchPin = 12; 
const int clockPin = 13; 
const int dataPin = 11;
const int buttonPin = 9;  

int time = 400;

const byte digitMap[] = {
  0b11110110, // 0
  0b10000100, // 1
  0b01101110, // 2
  0b11001110, // 3
  0b10011100, // 4
  0b11011010, // 5
  0b11111010, // 6
  0b10000110, // 7
  0b11111110, // 8
  0b11011110, // 9
  0b00000000  // 10
};

void setup() {
  pinMode(latchPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(dataPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);
  
}



void displayNumber(int myNumber) {
  digitalWrite(latchPin, LOW);                                // 1. Open the shifter gate
  shiftOut(dataPin, clockPin, MSBFIRST, digitMap[myNumber]);  // 2. Push the raw bits out
  digitalWrite(latchPin, HIGH);                               // 3. Close the gate to update the screen
}

void loop() {
  if (digitalRead(buttonPin) == LOW) {
    displayNumber(random(0, 10));
    delay(80);

  
}
}

I begin testing out my seven-segment display. I tested it out by using a power supply and a variable resistor.

I made sure every single segment works.

Then I wired the seven-segment display to my microcontroller and shift register.

Seven-segment display wired to the microcontroller and shift register

I then programmed a simple count up to nine program.

Then I began to make a random number generator with a display. I first added a button and made it turn on the number 9.

Then I added a random aspect to make it a true random generator. Instead of having the number appear only when the button is pressed,the button held its state while waiting for button clicks.