In this code, the background color changes depending on the random number between 0 and 255 transmitted from arduino nano BLE, Moreover different emojis are displayed as per the values.

The code can be used to track the button state.

When you press the connect button, wait till all charactristics are found

*/

const serviceU = "9EF4C2D8-41AD-4EA6-BB1A-1F532C3B6F46"; // UUID for the service

const buttonU = "8BCD218F-9C34-40AE-A13D-D607CE92EE94"; // UUID for the button

const randomInt = "7701D4B0-9EC1-4299-80ED-E7CC838A280C"; // UUID for random number

​

const service_UUID = serviceU.toLowerCase();

const button_UUID = buttonU.toLowerCase();

const random_UUID = randomInt.toLowerCase();

​

let randomN;

let button;

let BLEdevice;

​

let randomValue; // to hold the random value

​

//This contains emojis to be shown depending on the random value

const emojis = 

      [

  "😊", // Emoji for value 0-42

  "😄", // Emoji for value 43-85

  "😃", // Emoji for value 86-127

  "😎", // Emoji for value 128-170

  "🤩", // Emoji for value 171-213

  "😲", // Emoji for value 214-255

];

​

function setup() {

  createCanvas(500, 500);

​

  BLEdevice = new p5ble();

​

  const connectButton = createButton("Connect Device");// create a button that when pressed it connects to the devices

  connectButton.position(50, 50); 

  connectButton.mousePressed(connectDevice);//when presse connect to the Device

​

  const getValue = createButton("GET NEW VALUE");

  getValue.position(50, 150);

  getValue.mousePressed(controlButton);

}

​

function draw() {

  const backColor = map(randomValue, 0, 255, 0, 100);//mapping the values of the random values to values between 0 and 100 to achieve the combination below without having invalid values

  background(backColor + 155, 255 - backColor, 50 + backColor);

​

  textSize(20);

  textAlign(CENTER, CENTER);

  if (randomValue !== undefined) {

    const emojiIndex = Math.floor(map(randomValue, 0, 255, 0, emojis.length));

    const emojiToShow = emojis[emojiIndex];

    text(emojiToShow, width/2, height/2); // Display the emoji corresponding to randomValue

  } 

}

​

function searchForCharacteristics(error, characteristics) {

  if (error) {

    console.log("Error occurred: ", error);

    return;

  }

  for (let i = 0; i < characteristics.length; i++) {

    if (characteristics[i].uuid == button_UUID) {

      button = characteristics[i];

      console.log("Button Found");

    }

    if (characteristics[i].uuid == random_UUID) {

      randomN = characteristics[i];

      console.log("Random Int Found");

    }

  }

  if (!randomN) {

    console.log("Random Int Not Found");

  }

  if (!button) {

    console.log("Button Not Found");

  }

}

​

// Function to connect

function connectDevice() {

  BLEdevice.connect(service_UUID, searchForCharacteristics);

}

​

// Function to toggle the button status

function changeButtonStatus(error, data) {

  if (error) 

  {

    console.log("An error happened: ", error);

    return;

  }

  let newData = !data;

  BLEdevice.write(button, newData, checkError);

  //console.log("The button is set to: ",!data);

  retrieveValue();

}

function checkError(error)

{

  if(error)

    {

      console.log("Error writing button value");

      return;

    }

}

​

​

// Function to control the button 

function controlButton() {

  if (!button || !randomN) {

    console.log("Characteristics not found yet");

    return;

  }

  BLEdevice.read(button, changeButtonStatus); // Read the button status and toggle it

}

​

// Function to retrieve the random value

function retrieveValue() {

  BLEdevice.read(randomN, checkValue); // Read the random number

}

​

// Function to collect the value

function checkValue(error, value) {

  if (error) {

    console.log("Error occurred:", error);

    return;

  }

  randomValue = value; // Read the value to the declared vaiable

  console.log("Random Value: ", randomValue);

}

​

//function to retrieve the button value

function checkButtonValue(error, value) {

  if (error) {

    console.log("Error occurred:", error);

    return;

  }

  randomValue = value; // Read the value as Uint32

  console.log("The button is set to: ", randomValue);

}

​

​