/* * Project 14: ESP32 Wi-Fi + Bluetooth (BLE) Coexistence * Run a Wi-Fi web server and a BLE GATT server at the same time. Both read the * same DHT11 sensor and both control the same LED, kept in sync with each other. * * Pin map: * GPIO 4 -> DHT11 data (VCC to 3.3V, GND to GND) * GPIO 26 -> LED (through 220 ohm resistor to GND) * * Libraries: ESPAsyncWebServer, AsyncTCP, DHT sensor library, Adafruit Unified Sensor, * BLEDevice (ships with the ESP32 Arduino core, no extra install) * Serial: 115200 baud */ // Import required libraries #include "WiFi.h" #include "ESPAsyncWebServer.h" #include #include #include #include #include #include // Replace with your network credentials const char* ssid = "REPLACE_WITH_YOUR_SSID"; const char* password = "REPLACE_WITH_YOUR_PASSWORD"; #define DHTPIN 4 // Digital pin connected to the DHT sensor #define DHTTYPE DHT11 DHT dht(DHTPIN, DHTTYPE); #define LED_PIN 26 // Same three IDs, just the last hex digit changed: easy to tell apart while learning. #define SERVICE_UUID "12345678-1234-5678-1234-56789abcdef0" #define SENSOR_CHAR_UUID "12345678-1234-5678-1234-56789abcdef1" #define LED_CHAR_UUID "12345678-1234-5678-1234-56789abcdef2" #define BLE_DEVICE_NAME "ESP32-Kit-P14" // Create AsyncWebServer object on port 80 AsyncWebServer server(80); const char* PARAM_INPUT_1 = "state"; // Shared state: both the web server and the BLE server read and write these. bool ledState = false; String lastTempStr = "--"; String lastHumStr = "--"; BLECharacteristic *sensorChar; BLECharacteristic *ledChar; bool bleClientConnected = false; // Non-blocking sensor timer (Project 4's millis() pattern) unsigned long lastSensorRead = 0; const unsigned long SENSOR_INTERVAL = 3000; const char index_html[] PROGMEM = R"rawliteral(

Wi-Fi + Bluetooth, both live

ESP32 Coexistence Demo

%BUTTONPLACEHOLDER%

Temperature: %TEMPERATURE% °C

Humidity: %HUMIDITY% %

The same LED and the same sensor are also reachable over BLE. Connect with a BLE app (e.g. nRF Connect) while this page stays open, and watch both update.

)rawliteral"; // Replaces placeholders with live values in the web page String processor(const String& var){ if (var == "BUTTONPLACEHOLDER") { String checked = ledState ? "checked" : ""; return "

LED - GPIO 26 - State " + String(ledState ? "On" : "Off") + "

"; } if (var == "TEMPERATURE") return lastTempStr; if (var == "HUMIDITY") return lastHumStr; return String(); } // Sets the LED and pushes the new state into the BLE characteristic, so a BLE // client reading it afterward (from either source of a toggle) sees the truth. void setLed(bool on, const char* source){ ledState = on; digitalWrite(LED_PIN, ledState ? HIGH : LOW); ledChar->setValue(ledState ? "1" : "0"); Serial.printf("[%s] LED -> %s\n", source, ledState ? "ON" : "OFF"); } // BLE: a phone wrote to the LED characteristic class LedCallbacks: public BLECharacteristicCallbacks { void onWrite(BLECharacteristic *characteristic) override { String value = characteristic->getValue().c_str(); if (value.length() > 0) { setLed(value[0] == '1', "BLE"); } } }; // BLE: track whether a client is connected, so notify() is only called when it matters class ServerCallbacks: public BLEServerCallbacks { void onConnect(BLEServer* bleServer) override { bleClientConnected = true; Serial.println("[BLE] Client connected"); } void onDisconnect(BLEServer* bleServer) override { bleClientConnected = false; Serial.println("[BLE] Client disconnected, advertising again"); bleServer->startAdvertising(); } }; void setup(){ Serial.begin(115200); delay(500); Serial.println(); Serial.println("=============================================="); Serial.println(" Project 14: ESP32 Wi-Fi + Bluetooth Coexistence"); Serial.println("=============================================="); Serial.print ("DHT11 data -> GPIO "); Serial.println(DHTPIN); Serial.print ("LED -> GPIO "); Serial.println(LED_PIN); dht.begin(); pinMode(LED_PIN, OUTPUT); digitalWrite(LED_PIN, LOW); // Connect to Wi-Fi Serial.print("Connecting to Wi-Fi: "); Serial.println(ssid); WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(); Serial.println("Wi-Fi connected!"); Serial.print("Open this address in your browser: http://"); Serial.println(WiFi.localIP()); Serial.println("----------------------------------------------"); // Bring up BLE alongside the Wi-Fi connection that is already running BLEDevice::init(BLE_DEVICE_NAME); BLEServer *bleServer = BLEDevice::createServer(); bleServer->setCallbacks(new ServerCallbacks()); BLEService *service = bleServer->createService(SERVICE_UUID); sensorChar = service->createCharacteristic( SENSOR_CHAR_UUID, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_NOTIFY ); sensorChar->addDescriptor(new BLE2902()); // lets a client subscribe to notifications sensorChar->setValue("--,--"); ledChar = service->createCharacteristic( LED_CHAR_UUID, BLECharacteristic::PROPERTY_READ | BLECharacteristic::PROPERTY_WRITE ); ledChar->setValue("0"); ledChar->setCallbacks(new LedCallbacks()); service->start(); BLEAdvertising *advertising = BLEDevice::getAdvertising(); advertising->addServiceUUID(SERVICE_UUID); advertising->start(); Serial.print ("BLE advertising as: "); Serial.println(BLE_DEVICE_NAME); Serial.println("Scan for it in a BLE app (e.g. nRF Connect) while the Wi-Fi page stays open."); Serial.println("----------------------------------------------"); // Web routes server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, "text/html", index_html, processor); }); server.on("/temperature", HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, "text/plain", lastTempStr.c_str()); }); server.on("/humidity", HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, "text/plain", lastHumStr.c_str()); }); // GET /state (polled once a second to stay in sync with BLE toggles) server.on("/state", HTTP_GET, [](AsyncWebServerRequest *request){ request->send(200, "text/plain", ledState ? "1" : "0"); }); // GET /update?state=<0|1> (from the web toggle) server.on("/update", HTTP_GET, [](AsyncWebServerRequest *request){ if (request->hasParam(PARAM_INPUT_1)) { String inputMessage = request->getParam(PARAM_INPUT_1)->value(); setLed(inputMessage.toInt() == 1, "WEB"); } request->send(200, "text/plain", "OK"); }); server.begin(); } void loop(){ // Read the DHT11 on a timer, never inside a request handler: one reading feeds // both the web page's poll and the BLE notification below. if (millis() - lastSensorRead >= SENSOR_INTERVAL) { lastSensorRead = millis(); float t = dht.readTemperature(); float h = dht.readHumidity(); bool ok = true; if (isnan(t)) { Serial.println("[SENSOR] Failed to read temperature!"); ok = false; } else lastTempStr = String(t, 1); if (isnan(h)) { Serial.println("[SENSOR] Failed to read humidity!"); ok = false; } else lastHumStr = String(h, 1); if (ok) Serial.printf("[SENSOR] Temp: %.1f C Hum: %.1f %%\n", t, h); String payload = lastTempStr + "," + lastHumStr; sensorChar->setValue(payload.c_str()); if (bleClientConnected) sensorChar->notify(); } }