Add Library

libraries/ESP32_BLE_Arduino/examples/BLE_client/BLE_client.ino

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+/**
+ * A BLE client example that is rich in capabilities.
+ * There is a lot new capabilities implemented.
+ * author unknown
+ * updated by chegewara
+ */
+
+#include "BLEDevice.h"
+//#include "BLEScan.h"
+
+// The remote service we wish to connect to.
+static BLEUUID serviceUUID("4fafc201-1fb5-459e-8fcc-c5c9c331914b");
+// The characteristic of the remote service we are interested in.
+static BLEUUID    charUUID("beb5483e-36e1-4688-b7f5-ea07361b26a8");
+
+static boolean doConnect = false;
+static boolean connected = false;
+static boolean doScan = false;
+static BLERemoteCharacteristic* pRemoteCharacteristic;
+static BLEAdvertisedDevice* myDevice;
+
+static void notifyCallback(
+  BLERemoteCharacteristic* pBLERemoteCharacteristic,
+  uint8_t* pData,
+  size_t length,
+  bool isNotify) {
+    Serial.print("Notify callback for characteristic ");
+    Serial.print(pBLERemoteCharacteristic->getUUID().toString().c_str());
+    Serial.print(" of data length ");
+    Serial.println(length);
+    Serial.print("data: ");
+    Serial.println((char*)pData);
+}
+
+class MyClientCallback : public BLEClientCallbacks {
+  void onConnect(BLEClient* pclient) {
+  }
+
+  void onDisconnect(BLEClient* pclient) {
+    connected = false;
+    Serial.println("onDisconnect");
+  }
+};
+
+bool connectToServer() {
+    Serial.print("Forming a connection to ");
+    Serial.println(myDevice->getAddress().toString().c_str());
+    
+    BLEClient*  pClient  = BLEDevice::createClient();
+    Serial.println(" - Created client");
+
+    pClient->setClientCallbacks(new MyClientCallback());
+
+    // Connect to the remove BLE Server.
+    pClient->connect(myDevice);  // if you pass BLEAdvertisedDevice instead of address, it will be recognized type of peer device address (public or private)
+    Serial.println(" - Connected to server");
+
+    // Obtain a reference to the service we are after in the remote BLE server.
+    BLERemoteService* pRemoteService = pClient->getService(serviceUUID);
+    if (pRemoteService == nullptr) {
+      Serial.print("Failed to find our service UUID: ");
+      Serial.println(serviceUUID.toString().c_str());
+      pClient->disconnect();
+      return false;
+    }
+    Serial.println(" - Found our service");
+
+
+    // Obtain a reference to the characteristic in the service of the remote BLE server.
+    pRemoteCharacteristic = pRemoteService->getCharacteristic(charUUID);
+    if (pRemoteCharacteristic == nullptr) {
+      Serial.print("Failed to find our characteristic UUID: ");
+      Serial.println(charUUID.toString().c_str());
+      pClient->disconnect();
+      return false;
+    }
+    Serial.println(" - Found our characteristic");
+
+    // Read the value of the characteristic.
+    if(pRemoteCharacteristic->canRead()) {
+      std::string value = pRemoteCharacteristic->readValue();
+      Serial.print("The characteristic value was: ");
+      Serial.println(value.c_str());
+    }
+
+    if(pRemoteCharacteristic->canNotify())
+      pRemoteCharacteristic->registerForNotify(notifyCallback);
+
+    connected = true;
+}
+/**
+ * Scan for BLE servers and find the first one that advertises the service we are looking for.
+ */
+class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
+ /**
+   * Called for each advertising BLE server.
+   */
+  void onResult(BLEAdvertisedDevice advertisedDevice) {
+    Serial.print("BLE Advertised Device found: ");
+    Serial.println(advertisedDevice.toString().c_str());
+
+    // We have found a device, let us now see if it contains the service we are looking for.
+    if (advertisedDevice.haveServiceUUID() && advertisedDevice.isAdvertisingService(serviceUUID)) {
+
+      BLEDevice::getScan()->stop();
+      myDevice = new BLEAdvertisedDevice(advertisedDevice);
+      doConnect = true;
+      doScan = true;
+
+    } // Found our server
+  } // onResult
+}; // MyAdvertisedDeviceCallbacks
+
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println("Starting Arduino BLE Client application...");
+  BLEDevice::init("");
+
+  // Retrieve a Scanner and set the callback we want to use to be informed when we
+  // have detected a new device.  Specify that we want active scanning and start the
+  // scan to run for 5 seconds.
+  BLEScan* pBLEScan = BLEDevice::getScan();
+  pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
+  pBLEScan->setInterval(1349);
+  pBLEScan->setWindow(449);
+  pBLEScan->setActiveScan(true);
+  pBLEScan->start(5, false);
+} // End of setup.
+
+
+// This is the Arduino main loop function.
+void loop() {
+
+  // If the flag "doConnect" is true then we have scanned for and found the desired
+  // BLE Server with which we wish to connect.  Now we connect to it.  Once we are 
+  // connected we set the connected flag to be true.
+  if (doConnect == true) {
+    if (connectToServer()) {
+      Serial.println("We are now connected to the BLE Server.");
+    } else {
+      Serial.println("We have failed to connect to the server; there is nothin more we will do.");
+    }
+    doConnect = false;
+  }
+
+  // If we are connected to a peer BLE Server, update the characteristic each time we are reached
+  // with the current time since boot.
+  if (connected) {
+    String newValue = "Time since boot: " + String(millis()/1000);
+    Serial.println("Setting new characteristic value to \"" + newValue + "\"");
+    
+    // Set the characteristic's value to be the array of bytes that is actually a string.
+    pRemoteCharacteristic->writeValue(newValue.c_str(), newValue.length());
+  }else if(doScan){
+    BLEDevice::getScan()->start(0);  // this is just eample to start scan after disconnect, most likely there is better way to do it in arduino
+  }
+  
+  delay(1000); // Delay a second between loops.
+} // End of loop

libraries/ESP32_BLE_Arduino/examples/BLE_iBeacon/BLE_iBeacon.ino

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+/*
+   Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleScan.cpp
+   Ported to Arduino ESP32 by pcbreflux
+*/
+
+ 
+/*
+   Create a BLE server that will send periodic iBeacon frames.
+   The design of creating the BLE server is:
+   1. Create a BLE Server
+   2. Create advertising data
+   3. Start advertising.
+   4. wait
+   5. Stop advertising.
+   6. deep sleep
+   
+*/
+#include "sys/time.h"
+
+#include "BLEDevice.h"
+#include "BLEUtils.h"
+#include "BLEBeacon.h"
+#include "esp_sleep.h"
+
+#define GPIO_DEEP_SLEEP_DURATION     10  // sleep x seconds and then wake up
+RTC_DATA_ATTR static time_t last;        // remember last boot in RTC Memory
+RTC_DATA_ATTR static uint32_t bootcount; // remember number of boots in RTC Memory
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+uint8_t temprature_sens_read();
+//uint8_t g_phyFuns;
+
+#ifdef __cplusplus
+}
+#endif
+
+// See the following for generating UUIDs:
+// https://www.uuidgenerator.net/
+BLEAdvertising *pAdvertising;
+struct timeval now;
+
+#define BEACON_UUID           "8ec76ea3-6668-48da-9866-75be8bc86f4d" // UUID 1 128-Bit (may use linux tool uuidgen or random numbers via https://www.uuidgenerator.net/)
+
+void setBeacon() {
+
+  BLEBeacon oBeacon = BLEBeacon();
+  oBeacon.setManufacturerId(0x4C00); // fake Apple 0x004C LSB (ENDIAN_CHANGE_U16!)
+  oBeacon.setProximityUUID(BLEUUID(BEACON_UUID));
+  oBeacon.setMajor((bootcount & 0xFFFF0000) >> 16);
+  oBeacon.setMinor(bootcount&0xFFFF);
+  BLEAdvertisementData oAdvertisementData = BLEAdvertisementData();
+  BLEAdvertisementData oScanResponseData = BLEAdvertisementData();
+  
+  oAdvertisementData.setFlags(0x04); // BR_EDR_NOT_SUPPORTED 0x04
+  
+  std::string strServiceData = "";
+  
+  strServiceData += (char)26;     // Len
+  strServiceData += (char)0xFF;   // Type
+  strServiceData += oBeacon.getData(); 
+  oAdvertisementData.addData(strServiceData);
+  
+  pAdvertising->setAdvertisementData(oAdvertisementData);
+  pAdvertising->setScanResponseData(oScanResponseData);
+
+}
+
+void setup() {
+
+    
+  Serial.begin(115200);
+  gettimeofday(&now, NULL);
+
+  Serial.printf("start ESP32 %d\n",bootcount++);
+
+  Serial.printf("deep sleep (%lds since last reset, %lds since last boot)\n",now.tv_sec,now.tv_sec-last);
+
+  last = now.tv_sec;
+  
+  // Create the BLE Device
+  BLEDevice::init("");
+
+  // Create the BLE Server
+  // BLEServer *pServer = BLEDevice::createServer(); // <-- no longer required to instantiate BLEServer, less flash and ram usage
+
+  pAdvertising = BLEDevice::getAdvertising();
+  
+  setBeacon();
+   // Start advertising
+  pAdvertising->start();
+  Serial.println("Advertizing started...");
+  delay(100);
+  pAdvertising->stop();
+  Serial.printf("enter deep sleep\n");
+  esp_deep_sleep(1000000LL * GPIO_DEEP_SLEEP_DURATION);
+  Serial.printf("in deep sleep\n");
+}
+
+void loop() {
+}

libraries/ESP32_BLE_Arduino/examples/BLE_notify/BLE_notify.ino

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+/*
+    Video: https://www.youtube.com/watch?v=oCMOYS71NIU
+    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
+    Ported to Arduino ESP32 by Evandro Copercini
+    updated by chegewara
+
+   Create a BLE server that, once we receive a connection, will send periodic notifications.
+   The service advertises itself as: 4fafc201-1fb5-459e-8fcc-c5c9c331914b
+   And has a characteristic of: beb5483e-36e1-4688-b7f5-ea07361b26a8
+
+   The design of creating the BLE server is:
+   1. Create a BLE Server
+   2. Create a BLE Service
+   3. Create a BLE Characteristic on the Service
+   4. Create a BLE Descriptor on the characteristic
+   5. Start the service.
+   6. Start advertising.
+
+   A connect hander associated with the server starts a background task that performs notification
+   every couple of seconds.
+*/
+#include <BLEDevice.h>
+#include <BLEServer.h>
+#include <BLEUtils.h>
+#include <BLE2902.h>
+
+BLEServer* pServer = NULL;
+BLECharacteristic* pCharacteristic = NULL;
+bool deviceConnected = false;
+bool oldDeviceConnected = false;
+uint32_t value = 0;
+
+// See the following for generating UUIDs:
+// https://www.uuidgenerator.net/
+
+#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
+#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
+
+
+class MyServerCallbacks: public BLEServerCallbacks {
+    void onConnect(BLEServer* pServer) {
+      deviceConnected = true;
+    };
+
+    void onDisconnect(BLEServer* pServer) {
+      deviceConnected = false;
+    }
+};
+
+
+
+void setup() {
+  Serial.begin(115200);
+
+  // Create the BLE Device
+  BLEDevice::init("ESP32");
+
+  // Create the BLE Server
+  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,
+                      BLECharacteristic::PROPERTY_READ   |
+                      BLECharacteristic::PROPERTY_WRITE  |
+                      BLECharacteristic::PROPERTY_NOTIFY |
+                      BLECharacteristic::PROPERTY_INDICATE
+                    );
+
+  // https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
+  // Create a BLE Descriptor
+  pCharacteristic->addDescriptor(new BLE2902());
+
+  // Start the service
+  pService->start();
+
+  // Start advertising
+  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
+  pAdvertising->addServiceUUID(SERVICE_UUID);
+  pAdvertising->setScanResponse(false);
+  pAdvertising->setMinPreferred(0x0);  // set value to 0x00 to not advertise this parameter
+  BLEDevice::startAdvertising();
+  Serial.println("Waiting a client connection to notify...");
+}
+
+void loop() {
+    // notify changed value
+    if (deviceConnected) {
+        pCharacteristic->setValue((uint8_t*)&value, 4);
+        pCharacteristic->notify();
+        value++;
+        delay(3); // bluetooth stack will go into congestion, if too many packets are sent, in 6 hours test i was able to go as low as 3ms
+    }
+    // disconnecting
+    if (!deviceConnected && oldDeviceConnected) {
+        delay(500); // give the bluetooth stack the chance to get things ready
+        pServer->startAdvertising(); // restart advertising
+        Serial.println("start advertising");
+        oldDeviceConnected = deviceConnected;
+    }
+    // connecting
+    if (deviceConnected && !oldDeviceConnected) {
+        // do stuff here on connecting
+        oldDeviceConnected = deviceConnected;
+    }
+}

libraries/ESP32_BLE_Arduino/examples/BLE_scan/BLE_scan.ino

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+/*
+   Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleScan.cpp
+   Ported to Arduino ESP32 by Evandro Copercini
+*/
+
+#include <BLEDevice.h>
+#include <BLEUtils.h>
+#include <BLEScan.h>
+#include <BLEAdvertisedDevice.h>
+
+int scanTime = 5; //In seconds
+BLEScan* pBLEScan;
+
+class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
+    void onResult(BLEAdvertisedDevice advertisedDevice) {
+      Serial.printf("Advertised Device: %s \n", advertisedDevice.toString().c_str());
+    }
+};
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println("Scanning...");
+
+  BLEDevice::init("");
+  pBLEScan = BLEDevice::getScan(); //create new scan
+  pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
+  pBLEScan->setActiveScan(true); //active scan uses more power, but get results faster
+  pBLEScan->setInterval(100);
+  pBLEScan->setWindow(99);  // less or equal setInterval value
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  BLEScanResults foundDevices = pBLEScan->start(scanTime, false);
+  Serial.print("Devices found: ");
+  Serial.println(foundDevices.getCount());
+  Serial.println("Scan done!");
+  pBLEScan->clearResults();   // delete results fromBLEScan buffer to release memory
+  delay(2000);
+}

libraries/ESP32_BLE_Arduino/examples/BLE_server/BLE_server.ino

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+/*
+    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleServer.cpp
+    Ported to Arduino ESP32 by Evandro Copercini
+    updates by chegewara
+*/
+
+#include <BLEDevice.h>
+#include <BLEUtils.h>
+#include <BLEServer.h>
+
+// See the following for generating UUIDs:
+// https://www.uuidgenerator.net/
+
+#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
+#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
+
+void setup() {
+  Serial.begin(115200);
+  Serial.println("Starting BLE work!");
+
+  BLEDevice::init("Long name works now");
+  BLEServer *pServer = BLEDevice::createServer();
+  BLEService *pService = pServer->createService(SERVICE_UUID);
+  BLECharacteristic *pCharacteristic = pService->createCharacteristic(
+                                         CHARACTERISTIC_UUID,
+                                         BLECharacteristic::PROPERTY_READ |
+                                         BLECharacteristic::PROPERTY_WRITE
+                                       );
+
+  pCharacteristic->setValue("Hello World says Neil");
+  pService->start();
+  // BLEAdvertising *pAdvertising = pServer->getAdvertising();  // this still is working for backward compatibility
+  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
+  pAdvertising->addServiceUUID(SERVICE_UUID);
+  pAdvertising->setScanResponse(true);
+  pAdvertising->setMinPreferred(0x06);  // functions that help with iPhone connections issue
+  pAdvertising->setMinPreferred(0x12);
+  BLEDevice::startAdvertising();
+  Serial.println("Characteristic defined! Now you can read it in your phone!");
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  delay(2000);
+}

libraries/ESP32_BLE_Arduino/examples/BLE_server_multiconnect/BLE_server_multiconnect.ino

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+/*
+    Video: https://www.youtube.com/watch?v=oCMOYS71NIU
+    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
+    Ported to Arduino ESP32 by Evandro Copercini
+    updated by chegewara
+
+   Create a BLE server that, once we receive a connection, will send periodic notifications.
+   The service advertises itself as: 4fafc201-1fb5-459e-8fcc-c5c9c331914b
+   And has a characteristic of: beb5483e-36e1-4688-b7f5-ea07361b26a8
+
+   The design of creating the BLE server is:
+   1. Create a BLE Server
+   2. Create a BLE Service
+   3. Create a BLE Characteristic on the Service
+   4. Create a BLE Descriptor on the characteristic
+   5. Start the service.
+   6. Start advertising.
+
+   A connect hander associated with the server starts a background task that performs notification
+   every couple of seconds.
+*/
+#include <BLEDevice.h>
+#include <BLEServer.h>
+#include <BLEUtils.h>
+#include <BLE2902.h>
+
+BLEServer* pServer = NULL;
+BLECharacteristic* pCharacteristic = NULL;
+bool deviceConnected = false;
+bool oldDeviceConnected = false;
+uint32_t value = 0;
+
+// See the following for generating UUIDs:
+// https://www.uuidgenerator.net/
+
+#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
+#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
+
+
+class MyServerCallbacks: public BLEServerCallbacks {
+    void onConnect(BLEServer* pServer) {
+      deviceConnected = true;
+      BLEDevice::startAdvertising();
+    };
+
+    void onDisconnect(BLEServer* pServer) {
+      deviceConnected = false;
+    }
+};
+
+
+
+void setup() {
+  Serial.begin(115200);
+
+  // Create the BLE Device
+  BLEDevice::init("ESP32");
+
+  // Create the BLE Server
+  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,
+                      BLECharacteristic::PROPERTY_READ   |
+                      BLECharacteristic::PROPERTY_WRITE  |
+                      BLECharacteristic::PROPERTY_NOTIFY |
+                      BLECharacteristic::PROPERTY_INDICATE
+                    );
+
+  // https://www.bluetooth.com/specifications/gatt/viewer?attributeXmlFile=org.bluetooth.descriptor.gatt.client_characteristic_configuration.xml
+  // Create a BLE Descriptor
+  pCharacteristic->addDescriptor(new BLE2902());
+
+  // Start the service
+  pService->start();
+
+  // Start advertising
+  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
+  pAdvertising->addServiceUUID(SERVICE_UUID);
+  pAdvertising->setScanResponse(false);
+  pAdvertising->setMinPreferred(0x0);  // set value to 0x00 to not advertise this parameter
+  BLEDevice::startAdvertising();
+  Serial.println("Waiting a client connection to notify...");
+}
+
+void loop() {
+    // notify changed value
+    if (deviceConnected) {
+        pCharacteristic->setValue((uint8_t*)&value, 4);
+        pCharacteristic->notify();
+        value++;
+        delay(10); // bluetooth stack will go into congestion, if too many packets are sent, in 6 hours test i was able to go as low as 3ms
+    }
+    // disconnecting
+    if (!deviceConnected && oldDeviceConnected) {
+        delay(500); // give the bluetooth stack the chance to get things ready
+        pServer->startAdvertising(); // restart advertising
+        Serial.println("start advertising");
+        oldDeviceConnected = deviceConnected;
+    }
+    // connecting
+    if (deviceConnected && !oldDeviceConnected) {
+        // do stuff here on connecting
+        oldDeviceConnected = deviceConnected;
+    }
+}

libraries/ESP32_BLE_Arduino/examples/BLE_uart/BLE_uart.ino

@@ -0,0 +1,125 @@
+/*
+    Video: https://www.youtube.com/watch?v=oCMOYS71NIU
+    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleNotify.cpp
+    Ported to Arduino ESP32 by Evandro Copercini
+
+   Create a BLE server that, once we receive a connection, will send periodic notifications.
+   The service advertises itself as: 6E400001-B5A3-F393-E0A9-E50E24DCCA9E
+   Has a characteristic of: 6E400002-B5A3-F393-E0A9-E50E24DCCA9E - used for receiving data with "WRITE" 
+   Has a characteristic of: 6E400003-B5A3-F393-E0A9-E50E24DCCA9E - used to send data with  "NOTIFY"
+
+   The design of creating the BLE server is:
+   1. Create a BLE Server
+   2. Create a BLE Service
+   3. Create a BLE Characteristic on the Service
+   4. Create a BLE Descriptor on the characteristic
+   5. Start the service.
+   6. Start advertising.
+
+   In this example rxValue is the data received (only accessible inside that function).
+   And txValue is the data to be sent, in this example just a byte incremented every second. 
+*/
+#include <BLEDevice.h>
+#include <BLEServer.h>
+#include <BLEUtils.h>
+#include <BLE2902.h>
+
+BLEServer *pServer = NULL;
+BLECharacteristic * pTxCharacteristic;
+bool deviceConnected = false;
+bool oldDeviceConnected = false;
+uint8_t txValue = 0;
+
+// 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();
+        Serial.println("*********");
+      }
+    }
+};
+
+
+void setup() {
+  Serial.begin(115200);
+
+  // Create the BLE Device
+  BLEDevice::init("UART Service");
+
+  // Create the BLE Server
+  pServer = BLEDevice::createServer();
+  pServer->setCallbacks(new MyServerCallbacks());
+
+  // Create the BLE Service
+  BLEService *pService = pServer->createService(SERVICE_UUID);
+
+  // Create a BLE Characteristic
+  pTxCharacteristic = pService->createCharacteristic(
+										CHARACTERISTIC_UUID_TX,
+										BLECharacteristic::PROPERTY_NOTIFY
+									);
+                      
+  pTxCharacteristic->addDescriptor(new BLE2902());
+
+  BLECharacteristic * pRxCharacteristic = pService->createCharacteristic(
+											 CHARACTERISTIC_UUID_RX,
+											BLECharacteristic::PROPERTY_WRITE
+										);
+
+  pRxCharacteristic->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) {
+        pTxCharacteristic->setValue(&txValue, 1);
+        pTxCharacteristic->notify();
+        txValue++;
+		delay(10); // bluetooth stack will go into congestion, if too many packets are sent
+	}
+
+    // disconnecting
+    if (!deviceConnected && oldDeviceConnected) {
+        delay(500); // give the bluetooth stack the chance to get things ready
+        pServer->startAdvertising(); // restart advertising
+        Serial.println("start advertising");
+        oldDeviceConnected = deviceConnected;
+    }
+    // connecting
+    if (deviceConnected && !oldDeviceConnected) {
+		// do stuff here on connecting
+        oldDeviceConnected = deviceConnected;
+    }
+}

libraries/ESP32_BLE_Arduino/examples/BLE_write/BLE_write.ino

@@ -0,0 +1,65 @@
+/*
+    Based on Neil Kolban example for IDF: https://github.com/nkolban/esp32-snippets/blob/master/cpp_utils/tests/BLE%20Tests/SampleWrite.cpp
+    Ported to Arduino ESP32 by Evandro Copercini
+*/
+
+#include <BLEDevice.h>
+#include <BLEUtils.h>
+#include <BLEServer.h>
+
+// See the following for generating UUIDs:
+// https://www.uuidgenerator.net/
+
+#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
+#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"
+
+
+class MyCallbacks: public BLECharacteristicCallbacks {
+    void onWrite(BLECharacteristic *pCharacteristic) {
+      std::string value = pCharacteristic->getValue();
+
+      if (value.length() > 0) {
+        Serial.println("*********");
+        Serial.print("New value: ");
+        for (int i = 0; i < value.length(); i++)
+          Serial.print(value[i]);
+
+        Serial.println();
+        Serial.println("*********");
+      }
+    }
+};
+
+void setup() {
+  Serial.begin(115200);
+
+  Serial.println("1- Download and install an BLE scanner app in your phone");
+  Serial.println("2- Scan for BLE devices in the app");
+  Serial.println("3- Connect to MyESP32");
+  Serial.println("4- Go to CUSTOM CHARACTERISTIC in CUSTOM SERVICE and write something");
+  Serial.println("5- See the magic =)");
+
+  BLEDevice::init("MyESP32");
+  BLEServer *pServer = BLEDevice::createServer();
+
+  BLEService *pService = pServer->createService(SERVICE_UUID);
+
+  BLECharacteristic *pCharacteristic = pService->createCharacteristic(
+                                         CHARACTERISTIC_UUID,
+                                         BLECharacteristic::PROPERTY_READ |
+                                         BLECharacteristic::PROPERTY_WRITE
+                                       );
+
+  pCharacteristic->setCallbacks(new MyCallbacks());
+
+  pCharacteristic->setValue("Hello World");
+  pService->start();
+
+  BLEAdvertising *pAdvertising = pServer->getAdvertising();
+  pAdvertising->start();
+}
+
+void loop() {
+  // put your main code here, to run repeatedly:
+  delay(2000);
+}