In this part of my Arduino tutorial we’ll create 2 separate projects. First we’ll learn how 7 segment displays work and then create a dice simulation rolling circuit. We’ll then learn how to create a theremin, which is a weird instrument you can play without touching it. In addition we’ll learn about photoresistors, importing libraries, voltage dividers, map and much more.

All of the code follows the video below.

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Code from the Video

// CONTROLLING 7 SEGMENT DISPLAYS

// 7 Segment displays can represent individual numbers
// A common cathode display has all the cathodes connected 
// to ground and you turn on a segment by supplying current
// to its anode

// Pins are labeled starting at top left clockwise G, F, GND, A, B,
// DP, C, GND, D, E

// Add a library -> Sketch -> Include Library -> Manage Libraries
// Enter sevseg -> Click Install

#include "SevSeg.h"
SevSeg sevseg;

// The pin the button is connected to
const int buttonPin = 13;

// Stores buttons current state
int buttonState = 0;

// Stores buttons last state
int lastButtonState = 0;

void setup(){
  Serial.begin(9600);

  // Set pin 13 as an input from our button for finding a 
  // random digit
  pinMode(buttonPin, INPUT);
  
  // The number of digits on my display
  byte numDigits = 1;

  // Left empty for a single digit display
  byte digitPins[] = {};

  // Array that defines which pins are assigned to each segment
  // A - G, DP
  byte segmentPins[] = {6, 5, 2, 3, 4, 7, 8, 9};

  // True when the current limiting resistor is connected in series
  // like we did with the 1K Ohm resistor
  bool resistorsOnSegments = true;

  // I'm using a common cathode display (also COMMON_ANODE)
  byte hardwareConfig = COMMON_CATHODE;
  sevseg.begin(hardwareConfig, numDigits, digitPins, segmentPins,
  resistorsOnSegments);

  // Can change brightness from 0 - 100
  sevseg.setBrightness(90);

  // Set starting value as 0
  sevseg.setNumber(0);
  sevseg.refreshDisplay();
}

void loop(){
  // Get current button state
  buttonState = digitalRead(buttonPin);
  
  // Check the button state
  if(buttonState != lastButtonState){

    // Check if button was pressed
    if(buttonState == HIGH){

      // Print numbers out as if we are searching for 
      // a random value
      CycleNumbers();

      // Display the random number
      sevseg.setNumber(GetRandomNumber());
      sevseg.refreshDisplay();
    }

    // Added to avoid bouncing
    delay(50);
  }

  // Save the current state as the last state
  lastButtonState = buttonState;
  
  // Serial.println(GetRandomNumber());
}

// Cycles through numbers and displays them
void CycleNumbers(){
  for(int i = 0; i < 10; i++){
    sevseg.setNumber(i);
    sevseg.refreshDisplay();
    delay(200);
  }
}

// Returns a random value from 0 up to but not including 10
int GetRandomNumber(){

  // Initialize the random number generator with
  // a random seed value using an unconnected pin
  // which has a floating value 
  randomSeed(analogRead(0));
  return random(0,10);
}

// ARDUINO THEREMIN
// Will get the changing resistance from the photoresistor
// The photoresistor changes the resistance provided depending
// how much light it receives (Resistance increases with increasing light)
// It has no orientation like other resistors

// The photoresistor in series with the resistor is a circuit known
// as a Voltage Dividor
// They turn a large voltage into a smaller one
// Vout = Vin * R2 / R1 + R2

const int photoRPin = A0;

// Used to output a tone to the passive buzzer
const int buzzerOutPin = 11;

int photoRVal = 0;
int toneVal = 0;

void setup() {
  Serial.begin(9600);

}

void loop() {
  // Read resistance value from the analog port (0 (0V) - 1023 (5V))
  photoRVal = analogRead(photoRPin);
  Serial.print("Photoresistor : ");
  Serial.println(photoRVal);

  // Scale the output tone from 0 - 1023 to 120 - 1500
  // Tones normally range from 31 - 4978
  toneVal = map(photoRVal, 0, 1023, 120, 1500); 

  // Play a tone on the passive buzzer
  tone(buzzerOutPin, toneVal);

  // This delay pauses the program long enough to get another 
  // sensor reading (This should normally end your loops)
  delay(2);

}