XIAO 8-9-24 Sketch

include <ArduinoBLE.h>


// Theses are the BLE UUIDs
BLEService LEDService("f4b3c654-39f9-423a-8639-53010dc4301c");  //Service UUID hexadecimal numbers
BLEIntCharacteristic redCharacteristic("bc776cf6-50d7-41cf-9999-55df941b2b9d", BLERead | BLEWrite | BLENotify);
BLEIntCharacteristic greenCharacteristic("d3c69083-8afc-46d1-bd5a-fcca8893e7b2", BLERead | BLEWrite | BLENotify);
BLEIntCharacteristic blueCharacteristic("9e2d6c3f-98ea-4e7d-95ad-2b8a88fbf97a", BLERead | BLEWrite | BLENotify);

const int redPIN = LEDR;                            //pin to use for the red LED (D11)
const int greenPIN = LEDG;                          //pin to use for the green LED (D12)
const int bluePIN = LEDB;                           //pin to use for the red LED (D13)


void setup() {

  pinMode(redPIN, OUTPUT);                           //set pins as outputs and set LED's HiGH ( HIGH is off for this board)
  digitalWrite(redPIN, HIGH);
  pinMode(greenPIN, OUTPUT);
  digitalWrite(greenPIN, HIGH);
  pinMode(bluePIN, OUTPUT);
  digitalWrite(bluePIN, HIGH);

  if (!BLE.begin()) {                                      //  begin initialization
    while (1) ;                                              // wait until initialization is complete
  }

  BLE.setLocalName("BLE_RGB");                            // set advertised local name
  BLE.setAdvertisedService(LEDService);                   // set advertised service UUID
  LEDService.addCharacteristic(redCharacteristic);        // add the red characteristic to the service
  LEDService.addCharacteristic(greenCharacteristic);      // add the green characteristic to the service
  LEDService.addCharacteristic(blueCharacteristic);       // add the blue characteristic to the service
  BLE.addService(LEDService);                             // add service
  BLE.advertise();                                        // start advertising
}

void loop() {
  BLEDevice central = BLE.central();                      // listen for BLE devices to connect:  Not sure that this works for ESP32

  if (central) {                                          // if a central is connected to peripheral

                                                         // put code here to perform 1 time when device is connected

    while (central.connected()) {                        // While the central is still connected to peripheral

                                                         // if there is an update from the Android App, change light ON (0) or OFF (1)

      if (redCharacteristic.written()) digitalWrite(redPIN, redCharacteristic.value());
      if (greenCharacteristic.written()) digitalWrite(greenPIN, greenCharacteristic.value());
      if (blueCharacteristic.written()) digitalWrite(bluePIN, blueCharacteristic.value());

        }                                               // end of while loop

    }                                                   // you can put code here for what to do when not conected

}                                                       // end of loop