Add Bluetooth functionality to control LED via serial commands for app inventor

platformio.ini

@@ -16,3 +16,5 @@ framework = arduino
 lib_deps = 
 	adafruit/Adafruit SSD1306@^2.5.13
 	adafruit/Adafruit GFX Library@^1.11.11
+	mbed-seeed/BluetoothSerial@0.0.0+sha.f56002898ee8
+	adafruit/Adafruit BusIO@^1.16.2

src/save_mit_app

@@ -0,0 +1,60 @@
+#include "Arduino.h"
+#include "BluetoothSerial.h"
+#include <Wire.h>
+#include <SPI.h>
+
+BluetoothSerial SerialBT;
+
+const int LED_BUILTIN = 2;
+
+String receivedMessage = "";
+
+void processBluetoothMessage(String message);
+
+void setup() {
+    pinMode(LED_BUILTIN, OUTPUT);
+    digitalWrite(LED_BUILTIN, HIGH);
+
+    Serial.begin(115200);
+    Serial.println("Starting Bluetooth...");
+
+    if (!SerialBT.begin("ESP32 Yohan et Robin")) {
+        Serial.println("Error on starting Bluetooth");
+        while (1);
+    }
+
+    Serial.println("Bluetooth started, waitint for connections...");
+}
+
+void loop() {
+    if (SerialBT.available()) {
+        char receivedChar = SerialBT.read();
+
+        receivedMessage += receivedChar;
+        Serial.print("Current message: ");
+        Serial.println(receivedMessage);
+
+        if (receivedMessage.endsWith("o")) {
+            processBluetoothMessage("ON");
+            receivedMessage = "";
+        } else if (receivedMessage.endsWith("f")) {
+            processBluetoothMessage("OFF");
+            receivedMessage = "";
+        }
+    }
+}
+
+void processBluetoothMessage(String message) {
+    message.trim();
+    Serial.println("Received: " + message);
+
+    if (message.equalsIgnoreCase("ON")) {
+        digitalWrite(LED_BUILTIN, HIGH);
+        Serial.println("Turning LED ON");
+    } else if (message.equalsIgnoreCase("OFF")) {
+        digitalWrite(LED_BUILTIN, LOW);
+        Serial.println("Turning LED OFF");
+    } else {
+        Serial.println("Invalid command received");
+    }
+}