mbed-os-examples / Mbed OS mbed-os-example-ble-Beacon

This example creates a BLE beacon: a method of advertising a small amount of information to nearby devices. The information doesn't have to be human-readable; it can be in a format that only an application can use. Beacons are very easy to set up: the code for all beacons is the same, and only the information you want to advertise - the beacon payload - needs to change. he canonical source for this example lives at https://github.com/ARMmbed/mbed-os-example-ble/tree/master/BLE_Beacon

This example creates a BLE beacon: a method of advertising a small amount of information to nearby devices. The information doesn't have to be human-readable; it can be in a format that only an application can use.

Beacons are very easy to set up: the code for all beacons is the same, and only the information you want to advertise - the beacon payload - needs to change.

This example advertises a UUID, a major and minor number and the transmission strength. The major and minor numbers are an example of information that is not (normally) meaningful to humans, but that an application can use to identify the beacon and display related information. For example, if the major number is a store ID and the minor number is a location in that store, then a matching application can use these numbers to query a database and display location-specific information.

Running the application

Requirements

The sample application can be seen on any BLE scanner on a smartphone. If you don't have a scanner on your phone, please install :

- nRF Master Control Panel for Android.

- LightBlue for iPhone.

Hardware requirements are in the main readme.

Building instructions

In order to build this example in the mbed Online Compiler, first import the example using the ‘Import’ button on the right hand side.

Next, select a platform to build for. This must either be a platform that supports BLE, for example the NRF51-DK, or one of the following:

List of platforms supporting Bluetooth Low Energy

Or you must also add a piece of hardware and the supporting library that includes a Bluetooth Low Energy driver for that hardware, for example the K64F or NUCLEO_F401RE with the X-NUCLEO-IDB05A1

List of components supporting Bluetooth Low Energy.

Once you have selected your platform, compile the example and drag and drop the resulting binary onto your board.

For general instructions on using the mbed Online Compiler, please see the mbed Handbook

Checking for success

Note: Screens captures depicted below show what is expected from this example if the scanner used is nRF Master Control Panel version 4.0.5. If you encounter any difficulties consider trying another scanner or another version of nRF Master Control Panel. Alternative scanners may require reference to their manuals.

• Build the application and install it on your board as explained in the building instructions.
• Open the BLE scanner on your phone.
• Start a scan.

figure 1 How to start scan using nRF Master Control Panel 4.0.5

1. Find your device; it should be tagged as an `iBeacon` and observe its advertisements (there is no need to connect to the beacon).

figure 2 Scan results using nRF Master Control Panel 4.0.5

• View the beacon's details; the exact steps depend on which scanner you're using.

figure 3 Beacon details using nRF Master Control Panel 4.0.5

Tip: If you are in an area with many BLE devices, it may be difficult to identify your beacon. The simplest solution is to turn your board off and on, initiate a new scan on your BLE scanner every time, and look for the beacon that appears only when your board is on.

If you can see the beacon and all its information, the application worked properly.

For more information, see the mbed Classic version of this application.

/* mbed Microcontroller Library
 * Copyright (c) 2006-2015 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/services/iBeacon.h"

static iBeacon* ibeaconPtr;

static EventQueue eventQueue(/* event count */ 4 * EVENTS_EVENT_SIZE);

/**
 * 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 */
}

void printMacAddress()
{
    /* Print out device MAC address to the console*/
    Gap::AddressType_t addr_type;
    Gap::Address_t address;
    BLE::Instance().gap().getAddress(&addr_type, address);
    printf("DEVICE MAC ADDRESS: ");
    for (int i = 5; i >= 1; i--){
        printf("%02x:", address[i]);
    }
    printf("%02x\r\n", address[0]);
}

/**
 * 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;
    }

    /**
     * The Beacon payload has the following composition:
     * 128-Bit / 16byte UUID = E2 0A 39 F4 73 F5 4B C4 A1 2F 17 D1 AD 07 A9 61
     * Major/Minor  = 0x1122 / 0x3344
     * Tx Power     = 0xC8 = 200, 2's compliment is 256-200 = (-56dB)
     *
     * Note: please remember to calibrate your beacons TX Power for more accurate results.
     */
    static const uint8_t uuid[] = {0xE2, 0x0A, 0x39, 0xF4, 0x73, 0xF5, 0x4B, 0xC4,
                                   0xA1, 0x2F, 0x17, 0xD1, 0xAD, 0x07, 0xA9, 0x61};
    uint16_t majorNumber = 1122;
    uint16_t minorNumber = 3344;
    uint16_t txPower     = 0xC8;
    ibeaconPtr = new iBeacon(ble, uuid, majorNumber, minorNumber, txPower);

    ble.gap().setAdvertisingInterval(1000); /* 1000ms. */
    ble.gap().startAdvertising();

    printMacAddress();
}

void scheduleBleEventsProcessing(BLE::OnEventsToProcessCallbackContext* context) {
    BLE &ble = BLE::Instance();
    eventQueue.call(Callback<void()>(&ble, &BLE::processEvents));
}

int main()
{
    BLE &ble = BLE::Instance();
    ble.onEventsToProcess(scheduleBleEventsProcessing);
    ble.init(bleInitComplete);

    eventQueue.dispatch_forever();

    return 0;
}