Visualize sorting algorithms with Arduino and LED strip

Feel confused about sorting algorithms? Use LEDs and Arduino to get better understanding about them!

BeginnerFull instructions provided1 hour1,620

Things used in this project

Hardware components

Seeed Studio Seeeduino V4.2

Seeed Studio Base Shield V2

Seeed Studio Waterproof WS2813 RGB LED Strip Waterproof

Software apps and online services

Arduino IDE

Story

Sorting algorithms are the basic algorithms for beginners who want to learn computer science or programming. But sometimes you will get confused about how these algorithms work. Thus, there are plenty of visualizations of these sorting algorithms for beginners. But there are no visualization methods based on LEDs. Then I decided to implement one with Arduino and a LED strip.

Basic Concept

To implement a sorting algorithm, firstly you need an unsorted array. So I used a built-in random() function to generate an array filled with elements between (0, 30). And they are unsorted. To visualize those numbers, I created a setColor() function to convert a certain number to a RGB array. Then use the RGB array to set the color of a specified LED.

Step 1 Connect your hardware according to the schematics

Step 2 Run bubble sort code

bubble sort

As you can see, color red represents smaller values. During the sorting process, the red LEDs moved up like bubbles in water. That's why this sorting algorithm is called bubble sort.

More information about bubble sort

Step 3 Run quick sort code

quick sort

Quick sort is much more efficient than classical bubble sort.

More information about quick sort

Code

#include <FastLED.h>

#include "SparkFunLSM6DS3.h"
#include "Wire.h"
#include "math.h"

// Which pin on the Arduino is connected to the NeoLEDS?
#define NUM_LEDS 30
#define DATA_PIN 6
CRGB leds[NUM_LEDS];

int r, g, b;


void setup() {
  Serial.begin(9600);
  FastLED.addLeds<WS2812, DATA_PIN, RGB>(leds, NUM_LEDS);
  FastLED.setBrightness(100); //init led strip 
}

void loop() {
  bubbleSort(); //call bubbleSort function
  exit(0); //stop loop
}

void bubbleSort()
{ 
  int arr[NUM_LEDS]; //init an array with 30 elements
  for (int j = 0; j < NUM_LEDS; j++) 
  {
    int i = random(NUM_LEDS);
    arr[j] = i;
    setColor(i, j);
  }
  /* 
  give every led a randnom number between (0,30). The number will be used to generate a unique color to represent the value of the number
  */

  for (int m = 0; m < NUM_LEDS - 1; m++) {
    for (int n = 0; n < NUM_LEDS - 1 - m; n++) {
      if (arr[n] > arr[n + 1]) {
        setColor(arr[n + 1], n); // swap the larger number and smaller number
        setColor(arr[n], n + 1);
        int temp = arr[n + 1];
        arr[n + 1] = arr[n];
        arr[n] = temp;
      }
      // bubble sort algorithm
    }
  }
}
void setColor(int color, int led) { 
  // use an int number between (0,30) to determine the color of the specified led 
  if (color < NUM_LEDS / 3) {
    r = 255;
    g = floor(250 * 3 * color / NUM_LEDS);
    b = 0;
  } else if (color < NUM_LEDS / 2) {
    r = floor(750 - color * (250 * 6 / NUM_LEDS));
    g = 255;
    b = 0;
  } else if (color < NUM_LEDS * 2 / 3) {
    r = 0;
    g = 255;
    b = floor(color * (250 * 6 / NUM_LEDS) - 750);
  } else if (color < NUM_LEDS * 5 / 6) {
    r = 0;
    g = floor(1250 - color * (250 * 6 / NUM_LEDS));
    b = 255;
  } else {
    r = floor(150 * color * (6 / NUM_LEDS) - 750);
    g = 0;
    b = 255;
  } 
  leds[led].setRGB(g, r, b);
  FastLED.show(); // This sends the updated piaXel color to the hardware.
  delay(30);
}

#include <FastLED.h>

#include "SparkFunLSM6DS3.h"
#include "Wire.h"
#include "math.h"

// Which pin on the Arduino is connected to the NeoLEDS?
// On a Trinket or Gemma we suggest changing this to 1
#define NUM_LEDS 30
#define DATA_PIN 6
CRGB leds[NUM_LEDS];

int r, g, b;

void setup()
{
  Serial.begin(9600);
  FastLED.addLeds<WS2812, DATA_PIN, RGB>(leds, NUM_LEDS);
  FastLED.setBrightness(100); //init the led strip with 100 brightness
}

void loop()
{
  int arr[NUM_LEDS];
  for (int j = 0; j < NUM_LEDS; j++)
  {
    int i = random(NUM_LEDS);
    arr[j] = i;
    setColor(i, j);
  } //set the led strip with 30 random unique color representing different values
  quickSort(arr, 0, 29); // call quicksort function
      exit(0);
}

void quickSort(int num[], int l, int r)
{
  if (l >= r) 
    return;
  int m = l, n = r, x = num[l];
  while (m < n)
  {
    while (m < n && num[n] >= x) 
      n--;
    if (m < n)
    {
      setColor(num[n], m);
      num[m++] = num[n]; 
    }

    while (m < n && num[m] <= x) 
      m++;
    if (m < n)
    {
      setColor(num[m], n);
      num[n--] = num[m];
    }
  }
  num[m] = x;               //put the inital x into m element
  setColor(x, m);
  quickSort(num, l, m - 1); //use m as mid value, use recursive call
  quickSort(num, m + 1, r);
}
void setColor(int color, int led)
{
  if (color < NUM_LEDS / 3)
  {
    r = 255;
    g = floor(250 * 3 * color / NUM_LEDS);
    b = 0;
  }
  else if (color < NUM_LEDS / 2)
  {
    r = floor(750 - color * (250 * 6 / NUM_LEDS));
    g = 255;
    b = 0;
  }
  else if (color < NUM_LEDS * 2 / 3)
  {
    r = 0;
    g = 255;
    b = floor(color * (250 * 6 / NUM_LEDS) - 750);
  }
  else if (color < NUM_LEDS * 5 / 6)
  {
    r = 0;
    g = floor(1250 - color * (250 * 6 / NUM_LEDS));
    b = 255;
  }
  else
  {
    r = floor(150 * color * (6 / NUM_LEDS) - 750);
    g = 0;
    b = 255;
  }
  // convert an int value to rgb array
  leds[led].setRGB(g, r, b);
  FastLED.show(); // This sends the updated piaXel color to the hardware.
  delay(30);
}

Credits

memoryleak

5 projects • 7 followers

A soft and hardware engineer motivated by interest and fun

Visualize sorting algorithms with Arduino and LED strip