ESP32 BLUETOOTH LOW ENERGY (BLE) DENGAN DHT11

Praktikum kali ini yaitu mengirim pemberitahuan berupa data dari sensor DHT11.

Alat dan bahan yang digunakan :

• Board Esp32
• DHT11
• Arduino IDE
• Aplikasi BLE Scanner
• Kabel USB untuk menghubungkan board dengan komputer
• Led yang digunakan Led pada board Esp32.

Pada praktikum sebelumnya telah dibahas mengenai instalasi library yang digunakan, cara untuk mendapatkan kode UUID dan BLE scanner pada android. Halaman webnya bisa di akses disini.

Sketch program :

	#include <BLEDevice.h>
	#include <BLEServer.h>
	#include <BLEUtils.h>
	#include <BLE2902.h>
	#include <DHT.h>
	#include <iostream>
	#include <string>
	BLECharacteristic *pCharacteristic;
	bool deviceConnected = false;
	const int LED = 2; // Could be different depending on the dev board. I used the DOIT ESP32 dev board.
	/*
	* Definisi DHT11
	*/
	#define DHTPIN 23 // pino de dados do DHT11
	#define DHTTYPE DHT11 // DHT 11
	DHT dht(DHTPIN, DHTTYPE);
	int humidity;
	int temperature;
	// Kode UUID dari:
	// https://www.uuidgenerator.net/
	#define SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E" // UART service UUID
	#define CHARACTERISTIC_UUID_RX "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
	#define DHTDATA_CHAR_UUID "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
	class MyServerCallbacks: public BLEServerCallbacks {
	void onConnect(BLEServer* pServer) {
	deviceConnected = true;
	};
	void onDisconnect(BLEServer* pServer) {
	deviceConnected = false;
	}
	};
	class MyCallbacks: public BLECharacteristicCallbacks {
	void onWrite(BLECharacteristic *pCharacteristic) {
	std::string rxValue = pCharacteristic->getValue();
	Serial.println(rxValue[0]);
	if (rxValue.length() > 0) {
	Serial.println("*********");
	Serial.print("Received Value: ");
	for (int i = 0; i < rxValue.length(); i++) {
	Serial.print(rxValue[i]);
	}
	Serial.println();
	Serial.println("*********");
	}
	//Teks Masukan led, A:on , B:off
	if (rxValue.find("A") != -1) {
	Serial.println("Turning ON!");
	digitalWrite(LED, HIGH);
	}
	else if (rxValue.find("B") != -1) {
	Serial.println("Turning OFF!");
	digitalWrite(LED, LOW);
	}
	}
	};
	void setup() {
	Serial.begin(115200);
	pinMode(LED, OUTPUT);
	// Create the BLE Device
	BLEDevice::init("ESP32 DHT11"); // Give it a name
	// BLE Service
	BLEServer *pServer = BLEDevice::createServer();
	pServer->setCallbacks(new MyServerCallbacks());
	// UART service
	BLEService *pService = pServer->createService(SERVICE_UUID);
	// Karakter BLE untuk kirim data
	pCharacteristic = pService->createCharacteristic(
	DHTDATA_CHAR_UUID,
	BLECharacteristic::PROPERTY_NOTIFY
	);
	pCharacteristic->addDescriptor(new BLE2902());
	//karakteristik BLE untuk menerima data
	BLECharacteristic *pCharacteristic = pService->createCharacteristic(
	CHARACTERISTIC_UUID_RX,
	BLECharacteristic::PROPERTY_WRITE
	);
	pCharacteristic->setCallbacks(new MyCallbacks());
	// Mulai service
	pService->start();
	// Mulai ESP32
	pServer->getAdvertising()->start();
	Serial.println("Menunggu klien untuk terhubung...");
	}
	void loop() {
	if (deviceConnected) {
	humidity = dht.readHumidity();
	temperature = dht.readTemperature();
	if (isnan(temperature) || isnan(humidity))
	{
	Serial.println("Failed to read from DHT");
	}
	else
	{
	Serial.print("Kelembaban: ");
	Serial.print(humidity);
	Serial.print(" %\t");
	Serial.print("Suhu: ");
	Serial.print(temperature);
	Serial.println(" *C");
	}
	char humidityString[2];
	char temperatureString[2];
	dtostrf(humidity, 1, 2, humidityString);
	dtostrf(temperature, 1, 2, temperatureString);
	char dhtDataString[16];
	sprintf(dhtDataString, "%d,%d", temperature, humidity);
	pCharacteristic->setValue(dhtDataString);
	pCharacteristic->notify(); // Kirim nilai ke aplikasi!
	Serial.print("*** Terkirim ke BLE Scanner ");
	Serial.print(dhtDataString);
	Serial.println(" ***");
	}
	delay(1000);
	}

view raw BLE_ESP32_DHT11 hosted with ❤ by GitHub

Setelah selesai menuliskan kode pada Arduino IDE, kemudian pilih board ESP32 dan sesuaikan port yang digunakan selanjutnya upload Sketch Program, tunggu hingga proses upload selesai dan buka serial monitor pilih range 115200 baud, tekan EN pada board.
Maka akan muncul seperti gambar dibawah ini:

Serial Monitor

Selanjutnya hubungkan Bluetooth pada board dengan aplikasi BLE Scanner yang telah diinstall di smartphone dengan menekan CONNECT.

Halaman depan app

Kemudian akan diarahkan ke menu device yang terhubung, pilih CUSTOM SERVICE dan klik huruf N pada sisi kanan layar untuk mengaktifkan notifikasi.

Data pada serial monitor

Data pada applikasi BLE scanner

Note : Terlihat data yang dihasilkan dari sensor kurang akurat

*source : www.filipeflop.com