This example creates and updates a standard Battery Level service containing a single GATT characteristic with mbed OS 5.

Revision:
0:d9a87d1192f6
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Fri Jun 02 14:29:32 2017 +0000
@@ -0,0 +1,114 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2014 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <events/mbed_events.h>
+#include <mbed.h>
+#include "ble/BLE.h"
+#include "ble/Gap.h"
+#include "ble/services/BatteryService.h"
+
+DigitalOut led1(LED1, 1);
+
+const static char     DEVICE_NAME[] = "BATTERY";
+static const uint16_t uuid16_list[] = {GattService::UUID_BATTERY_SERVICE};
+
+static uint8_t batteryLevel = 50;
+static BatteryService* batteryServicePtr;
+
+static EventQueue eventQueue(/* event count */ 16 * EVENTS_EVENT_SIZE);
+
+void disconnectionCallback(const Gap::DisconnectionCallbackParams_t *params)
+{
+    BLE::Instance().gap().startAdvertising();
+}
+
+void updateSensorValue() {
+    batteryLevel++;
+    if (batteryLevel > 100) {
+        batteryLevel = 20;
+    }
+
+    batteryServicePtr->updateBatteryLevel(batteryLevel);
+}
+
+void blinkCallback(void)
+{
+    led1 = !led1; /* Do blinky on LED1 while we're waiting for BLE events */
+
+    BLE &ble = BLE::Instance();
+    if (ble.gap().getState().connected) {
+        eventQueue.call(updateSensorValue);
+    }
+}
+
+/**
+ * This function is called when the ble initialization process has failled
+ */
+void onBleInitError(BLE &ble, ble_error_t error)
+{
+    /* Initialization error handling should go here */
+}
+
+/**
+ * Callback triggered when the ble initialization process has finished
+ */
+void bleInitComplete(BLE::InitializationCompleteCallbackContext *params)
+{
+    BLE&        ble   = params->ble;
+    ble_error_t error = params->error;
+
+    if (error != BLE_ERROR_NONE) {
+        /* In case of error, forward the error handling to onBleInitError */
+        onBleInitError(ble, error);
+        return;
+    }
+
+    /* Ensure that it is the default instance of BLE */
+    if(ble.getInstanceID() != BLE::DEFAULT_INSTANCE) {
+        return;
+    }
+
+    ble.gap().onDisconnection(disconnectionCallback);
+
+    /* Setup primary service */
+    batteryServicePtr = new BatteryService(ble, batteryLevel);
+
+    /* Setup advertising */
+    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED | GapAdvertisingData::LE_GENERAL_DISCOVERABLE);
+    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LIST_16BIT_SERVICE_IDS, (uint8_t *) uuid16_list, sizeof(uuid16_list));
+    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME, (uint8_t *) DEVICE_NAME, sizeof(DEVICE_NAME));
+    ble.gap().setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED);
+    ble.gap().setAdvertisingInterval(1000); /* 1000ms */
+    ble.gap().startAdvertising();
+}
+
+void scheduleBleEventsProcessing(BLE::OnEventsToProcessCallbackContext* context) {
+    BLE &ble = BLE::Instance();
+    eventQueue.call(Callback<void()>(&ble, &BLE::processEvents));
+}
+
+int main()
+{
+    eventQueue.call_every(500, blinkCallback);
+
+    BLE &ble = BLE::Instance();
+    ble.onEventsToProcess(scheduleBleEventsProcessing);
+    ble.init(bleInitComplete);
+
+    eventQueue.dispatch_forever();
+
+    return 0;
+}