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34902f4 Oct 13, 2017
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* A BLE client example that is rich in capabilities.
#include "BLEDevice.h"
//#include "BLEScan.h"
// The remote service we wish to connect to.
static BLEUUID serviceUUID("91bad492-b950-4226-aa2b-4ede9fa42f59");
// The characteristic of the remote service we are interested in.
static BLEUUID charUUID("0d563a58-196a-48ce-ace2-dfec78acc814");
static BLEAddress *pServerAddress;
static boolean doConnect = false;
static boolean connected = false;
static BLERemoteCharacteristic* pRemoteCharacteristic;
static void notifyCallback(
BLERemoteCharacteristic* pBLERemoteCharacteristic,
uint8_t* pData,
size_t length,
bool isNotify) {
Serial.print("Notify callback for characteristic ");
Serial.print(" of data length ");
bool connectToServer(BLEAddress pAddress) {
Serial.print("Forming a connection to ");
BLEClient* pClient = BLEDevice::createClient();
Serial.println(" - Created client");
// Connect to the remove BLE Server.
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: ");
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: ");
return false;
Serial.println(" - Found our characteristic");
// Read the value of the characteristic.
std::string value = pRemoteCharacteristic->readValue();
Serial.print("The characteristic value was: ");
* 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: ");
// We have found a device, let us now see if it contains the service we are looking for.
if (advertisedDevice.haveServiceUUID() && advertisedDevice.getServiceUUID().equals(serviceUUID)) {
Serial.print("Found our device! address: ");
pServerAddress = new BLEAddress(advertisedDevice.getAddress());
doConnect = true;
} // Found our server
} // onResult
}; // MyAdvertisedDeviceCallbacks
void setup() {
Serial.println("Starting Arduino BLE Client application...");
// 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 30 seconds.
BLEScan* pBLEScan = BLEDevice::getScan();
pBLEScan->setAdvertisedDeviceCallbacks(new MyAdvertisedDeviceCallbacks());
} // 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(*pServerAddress)) {
Serial.println("We are now connected to the BLE Server.");
connected = true;
} 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());
delay(1000); // Delay a second between loops.
} // End of loop