The Uniform Resource Identifier Beacon (UriBeacon) defines Bluetooth 4.0 Advertisement Data that contain Web URIs. URIBeacon provides a way for Bluetooth Low Energy devices to discover nearby URIs, for example, provides a way for a user to discover a short URL and then download it on their smartphone.

Dependencies:   BLE_API mbed nRF51822

Fork of BLE_PhysicalWeb by Bluetooth Low Energy

This example demonstrates how to set up and initialize a basic URI Beacon. For a more advanced example of using a URI beacon please see the BLE_PhysicalWeb project. The Google Github Page also gives a great description of what UriBeacons are and how to use them.

Basic Details

URI Beacons are a standard way of providing a URI link in a BLE advertising packet. Website URL's are the most popular URI's. The goal of URI Beacons are to act as a bridge between the physical and digital worlds. Since the URI can be any web capable link the possibilities for use are really endless. The UriBeacons can be thought of as a natural extension of and more useful version of QR codes.

Smartphone App Links

iPhone Physical Web app

Android App

Walkthrough of Physical Web application

Size of URI

The UriBeacon has one purpose, to advertise a web link. Because of the nature of BLE these web links have to be small. In order to provide a nice balance of small and useful the UriBeacon specification has abstracted out the representation of the URI prefix('http://www.', 'https://www.' , ...etc) and suffix ('.com','.org','.edu','.gov' ...etc) to a single byte each. Of the 27 bytes available for a usual BLE payload the UriBeacon has 19 bytes available for the URI. Of these 19bytes one byte must be given to the prefix. That leaves 18 bytes to fit the address and the suffix into. If the suffix used is not one of the standard ones in the UriBeacon specification then each letter will take up 1 byte instead of the entire suffix being abbreviated into a single byte.

Here are the acceptable abbreviations currently available


So for example the address "" would take up 8 bytes. Both "http://www." and ".com" are supported abbreviations so each will be shortened to 1 byte.

Number of BytesData
1"http://www." abbreviated
6"google", 1 byte for each letter
1".com/" abbreviated

An address like "" would take up 11 bytes. Notice that ".ly" is not a supported suffix, so each letter takes up 1 byte.

Number of BytesData
1"http://www." abbreviated

Even addresses with the suffix in the middle are abbreviated, ie "". Notice here that the '.com' is in the middle of an address, it is still shortened to just 1 byte.

Number of BytesData
1"http://www." abbreviated
1".com/" abbreviated

Using UriBeacons with mbed BLE API

Using the UriBeacon with the mbed API is rather simple. Just like any other BLE project you must first initialize the BLE baselayer by creating a ble object.


BLEDevice ble;

Then you pass the BLE object to a UriBeacon config service.


URIBeaconConfigService *uriBeaconConfig;
uriBeaconConfig = new URIBeaconConfigService(ble, "");

Optionally you can then adjust settings of the UriBeacon such as transmission power levels, grabbing verbose debug information and other handy dandy services.


/* Adjust the TX Power Level */
    const int8_t powerLevels[] = {-20, -4, 0, 10};
    uriBeaconConfig->setTxPowerLevels(powerLevels); // Set TX power levels, Lowest(-20), Low(-4), Medium(0), High(10)
    uriBeaconConfig->setTxPowerMode(URIBeaconConfigService::TX_POWER_MODE_LOW); // Set transmission in Low power mode

/* Adjust Beacon Period*/
setBeaconPeriod(1000); // Set beacon to advertise every 1000ms

Other UriBeacon Services

This is just the bare basics of how URI beacons work. There is also a configuration service that allows URI beacons to be updated, locked, and provides other management feature. That is beyond the scope of this example but details can be found in the Technical Details section below.

Technical Details

For more details on how URI beacons work please see these websites:
UriBeacon Github Project : the github home for all things UriBeacon (maintained by google)
UriBeacon Specification : lots of good technical details
UriBeacon configuration service - This is a service that pairs with the UriBeacon that allows changing the URI's, locking them, and some other cool features. This service is not detailed in this example application.
Android App : smartphone application to view nearby UriBeacons.
iOS App : Sample code for using UriBeacons with iOS.
The PhysicalWeb Project : a project that the UriBeacon is central to.

In case you're really interested here is a diagram that nicely sums up how the 27bytes of advertising data payload are used.



File content as of revision 29:5a1112254406:

/* 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * See the License for the specific language governing permissions and
 * limitations under the License.

#include "mbed.h"
#include "ble/BLE.h"
#include "ble/services/URIBeaconConfigService.h"
#include "ble/services/DFUService.h"
#include "ble/services/DeviceInformationService.h"
#include "ConfigParamsPersistence.h"

URIBeaconConfigService *uriBeaconConfig;

 * URIBeaconConfig service can operate in two modes: a configuration mode which
 * allows a user to update settings over a connection; and normal URIBeacon mode
 * which involves advertising a URI. Constructing an object from URIBeaconConfig
 * service sets up advertisements for the configuration mode. It is then up to
 * the application to switch to URIBeacon mode based on some timeout.
 * The following help with this switch.
static const int CONFIG_ADVERTISEMENT_TIMEOUT_SECONDS = 60;  // Duration after power-on that config service is available.
Ticker configAdvertisementTimeoutTicker;

 * Stop advertising the UriBeaconConfig Service after a delay; and switch to normal URIBeacon.
void timeout(void)
    Gap::GapState_t state;
    BLE& ble = BLE::Instance(BLE::DEFAULT_INSTANCE);

    state = ble.getGapState();
    if (!state.connected) { /* don't switch if we're in a connected state. */

        configAdvertisementTimeoutTicker.detach(); /* disable the callback from the timeout Ticker. */

 * Callback triggered upon a disconnection event. Needs to re-enable advertisements.
void disconnectionCallback(const Gap::DisconnectionCallbackParams_t *)
    BLE& ble = BLE::Instance(BLE::DEFAULT_INSTANCE);

void bleInitComplete(BLE::InitializationCompleteCallbackContext *context)
    BLE &ble          = context->ble;

    if (context->error != BLE_ERROR_NONE) {


     * Load parameters from (platform specific) persistent storage. Parameters
     * can be set to non-default values while the URIBeacon is in configuration
     * mode (within the first 60 seconds of power-up). Thereafter, parameters
     * get copied out to persistent storage before switching to normal URIBeacon
     * operation.
    URIBeaconConfigService::Params_t params;
    bool fetchedFromPersistentStorage = loadURIBeaconConfigParams(&params);

    /* Initialize a URIBeaconConfig service providing config params, default URI, and power levels. */
    static URIBeaconConfigService::PowerLevels_t defaultAdvPowerLevels = {-20, -4, 0, 10}; // Values for ADV packets related to firmware levels
    uriBeaconConfig = new URIBeaconConfigService(ble, params, !fetchedFromPersistentStorage, "", defaultAdvPowerLevels);
    if (!uriBeaconConfig->configuredSuccessfully()) {
        error("failed to accommodate URI");
    configAdvertisementTimeoutTicker.attach(timeout, CONFIG_ADVERTISEMENT_TIMEOUT_SECONDS);

    // Setup auxiliary services to allow over-the-air firmware updates, etc
    DFUService dfu(ble);
    DeviceInformationService deviceInfo(ble, "ARM", "UriBeacon", "SN1", "hw-rev1", "fw-rev1", "soft-rev1");

    ble.startAdvertising(); /* Set the whole thing in motion. After this call a GAP central can scan the URIBeaconConfig
                             * service. This can then be switched to the normal URIBeacon functionality after a timeout. */

int main(void)
    BLE& ble = BLE::Instance(BLE::DEFAULT_INSTANCE);

    /* SpinWait for initialization to complete. This is necessary because the
     * BLE object is used in the main loop below. */
    while (!ble.hasInitialized()) { /* spin loop */ }

    while (true) {