BLE_uart example

clowrey · clowrey · commit 9cb4b0533ea0 · 2017-08-28T17:28:46.000-10:00
Combines the Notify and Write examples to create a basic UART example
that works with the Nordic nRF Android app and many others. Could use a
Print function and possibly read function, but basic RX/TX does work.
diff --git a/cpp_utils/tests/BLETests/Arduino/BLE_uart/BLE_uart.ino b/cpp_utils/tests/BLETests/Arduino/BLE_uart/BLE_uart.ino
@@ -0,0 +1,111 @@
+/*
+    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>
+
+BLECharacteristic *pCharacteristic;
+bool deviceConnected = 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
+  BLEServer *pServer = new BLEServer();
+  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) {
+    Serial.printf("*** Sent Value: %d ***\n", txValue);
+    pCharacteristic->setValue(&txValue, 1);
+    pCharacteristic->notify();
+    txValue++;
+  }
+  delay(1000);
+}
