Connect a board via BLE with a app on MIT App Inventor

1#include <ArduinoBLE.h>
2
3// Define a custom BLE service and characteristic
4BLEService ledService("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX");  // Replace with your own UUID
5BLEUnsignedCharCharacteristic ledCharacteristic("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX", BLEWrite | BLEWriteWithoutResponse);
6
7void setup() {
8  Serial.begin(9600);
9
10  // Initialize BLE
11  if (!BLE.begin()) {
12    Serial.println("Failed to start BLE!");
13    while (1)
14      ;
15  }
16
17  // Set the device name and advertise the service
18  BLE.setLocalName("LEDPeripheral");
19  BLE.setAdvertisedService(ledService);
20
21  // Attach the characteristic to the service
22  ledService.addCharacteristic(ledCharacteristic);
23
24  // Register the service with the BLE stack
25  BLE.addService(ledService);
26
27  // Set an initial value for the characteristic
28  ledCharacteristic.writeValue(0);
29
30  // Start advertising the BLE service
31  BLE.advertise();
32  Serial.println("BLE LED Peripheral is now advertising...");
33}
34
35void loop() {
36  // Wait for a central device to connect
37  BLEDevice central = BLE.central();
38
39  if (central) {
40    Serial.print("Connected to: ");
41    Serial.println(central.address());
42
43    // Stay in loop while the central is connected
44    while (central.connected()) {
45      // Check if the characteristic has been updated by the central
46      if (ledCharacteristic.written()) {
47        // Read the new value from the characteristic
48        int ledValue = ledCharacteristic.value();
49        Serial.print("Received value: ");
50        Serial.println(ledValue);
51      }
52    }
53
54    // Handle disconnection
55    Serial.print("Disconnected from: ");
56    Serial.println(central.address());
57  }
58}