#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>
BLECharacteristic *pCharacteristic;
bool deviceConnected = false;
float txValue = 0;
const int readPin = 32; // Use GPIO number. See ESP32 board pinouts
const int LED = 2; // Could be different depending on the dev board. I used the DOIT ESP32 dev board.
//std::string rxValue; // Could also make this a global var to access it in loop()
// See the following for generating UUIDs:
// 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 CHARACTERISTIC_UUID_TX "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();
if (rxValue.length() > 0) {
Serial.println("*********");
Serial.print("Received Value: ");
for (int i = 0; i < rxValue.length(); i++) {
Serial.print(rxValue[i]);
}
Serial.println();
// Do stuff based on the command received from the app
if (rxValue.find("A") != -1) {
Serial.print("Turning ON!");
digitalWrite(LED, HIGH);
} else if (rxValue.find("B") != -1) {
Serial.print("Turning OFF!");
digitalWrite(LED, LOW);
}
Serial.println();
Serial.println("*********");
}
}
};
void setup() {
Serial.begin(115200);
pinMode(LED, OUTPUT);
// Create the BLE Device
BLEDevice::init("ESP32 UART Test"); // Give it a name
// Create the BLE Server
BLEServer *pServer = BLEDevice::createServer();
pServer->setCallbacks(new MyServerCallbacks());
// Create the BLE Service
BLEService *pService = pServer->createService(SERVICE_UUID);
// Create a BLE Characteristic
pCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_TX,BLECharacteristic::PROPERTY_NOTIFY);
pCharacteristic->addDescriptor(new BLE2902());
BLECharacteristic *pCharacteristic = pService->createCharacteristic(CHARACTERISTIC_UUID_RX,BLECharacteristic::PROPERTY_WRITE);
pCharacteristic->setCallbacks(new MyCallbacks());
// Start the service
pService -> start();
// Start advertising
pServer -> getAdvertising() -> start();
Serial.println("Waiting a client connection to notify...");
}
void loop() {
if (deviceConnected) {
// Fabricate some arbitrary junk for now...
txValue = analogRead(readPin) / 3.456; // This could be an actual sensor reading!
// Let's convert the value to a char array:
char txString[8]; // make sure this is big enuffz
dtostrf(txValue, 1, 2, txString); // float_val, min_width, digits_after_decimal, char_buffer
//pCharacteristic -> setValue(&txValue, 1); // To send the integer value
//pCharacteristic -> setValue("Hello!"); // Sending a test message
pCharacteristic -> setValue(txString);
pCharacteristic -> notify(); // Send the value to the app!
Serial.print("*** Sent Value: ");
Serial.print(txString);
Serial.println(" ***");
}
delay(1000);
}
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