File content as of revision 4:5b64235d1b85:

/* mbed Microcontroller Library
 * Copyright (c) 2006-2013 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 "mbed.h"
#include "BLEDevice.h"

BLEDevice  ble;

DigitalOut led1(LED1);

#define NEED_CONSOLE_OUTPUT 0 /* Set this if you need debug messages on the console;
                               * it will have an impact on code-size and power
                               * consumption. */

#if NEED_CONSOLE_OUTPUT
Serial  pc(USBTX, USBRX);
#define DEBUG(...) { pc.printf(__VA_ARGS__); }
#else
#define DEBUG(...) /* nothing */
#endif /* #if NEED_CONSOLE_OUTPUT */

/* Battery Level Service */
uint8_t            batt      = 72; /* Battery level */
GattCharacteristic battLevel   (GattCharacteristic::UUID_BATTERY_LEVEL_CHAR, &batt, sizeof(batt), sizeof(batt),
                                GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY | GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_READ);
GattCharacteristic *battChars[] = {
    &battLevel,
};
GattService        battService (GattService::UUID_BATTERY_SERVICE, battChars, sizeof(battChars) / sizeof(GattCharacteristic *));


void disconnectionCallback(void)
{
    DEBUG("Disconnected!\n\r");
    DEBUG("Restarting the advertising process\n\r");
    ble.startAdvertising();
}

/**
 * Runs once a second in interrupt context triggered by the 'ticker'; updates
 * battery level if there is a connection.
 */
void periodicCallback(void)
{
    led1 = !led1; /* Do blinky on LED1 while we're waiting for BLE events */

    if (ble.getGapState().connected) {
        /* Update battery level */
        batt++;
        if (batt > 100) {
            batt = 72;
        }
        ble.updateCharacteristicValue(battLevel.getHandle(), (uint8_t *)&batt, sizeof(batt));
    }
}

int main(void)
{
    led1 = 1;
    Ticker ticker;
    ticker.attach(periodicCallback, 1);

    DEBUG("Initialising the nRF51822\n\r");
    ble.init();
    ble.onDisconnection(disconnectionCallback);

    /* setup advertising */
    ble.accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED);
    ble.setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED);
    ble.setAdvertisingInterval(160); /* 100ms; in multiples of 0.625ms. */
    ble.startAdvertising();

    ble.addService(battService);

    while (true) {
        ble.waitForEvent();
    }
}