BLE Beacon Bluetooth Low Energy allows devices to broadcast some information. Such broadcasting is known as Bluetooth LE Advertisement. It is widely used by BLE devices to transmit data without establishing a connection. The advertising is also used during the discovery process and includes important information about Bluetooth-enabled devices.

The common usage of Bluetooth LE Advertising is Bluetooth Beacons. A BLE beacon is a hardware transmitter - a class of Bluetooth Low Energy devices that broadcasts its identifier to nearby portable electronic devices. The technology enables smartphones, tablets, and other devices to perform actions when in close proximity to a beacon. Also, Apple uses Bluetooth LE Advertising in their Continuity protocol.

Bluetooth Framework provides methods to capture and decode Bluetooth LE advertisement packets (also known as frames) as well as build and broadcast your own (custom) advertisements. This feature is supported with Microsoft Bluetooth drivers on Windows 10 and above and with the BLED112 USB Bluetooth dongle on any Windows platform. The library package includes the Beacons sample application that shows how to enable Bluetooth LE advertisements capturing and broadcasting.

Receive BLE Advertisements

Bluetooth Framework provides a class that allows your application to monitor Bluetooth LE devices and to capture their advertisement frames. The class can decode the following Bluetooth LE advertisements (other unknown frames are reported to an application as a raw byte array, so the application can handle any type of frame):

  • Appearance
  • Basic Information
  • Extended Information
  • 16 bit Service Data
  • 32 bit Service Data
  • 128 bit Service Data
  • 16 bit Solicitation Service
  • 32 bit Solicitation Service
  • 128 bit Solicitation Service
  • TX Power
  • 128 bit UUID
  • Alt Beacon
  • Eddystone TLM
  • Eddystone UID
  • Eddystone URL
  • Apple Continuity
  • Microsoft CDP Beacon
  • Drone Remote ID
  • Manufacturer Raw

Transmit BLE Advertising

Bluetooth Framework provides a class that switches your application to Bluetooth LE Advertiser mode. The class allows advertising a few predefined advertisements as well as any custom advertisement (there are some restrictions described below).

Supported Advertisement Types

The following advertisement types are reserved and are not allowed:

Data TypeConstant (wclUUIDs)Description
0x00LE_GAP_AD_TYPE_NONEEmpty flags
0x01LE_GAP_AD_TYPE_FLAGSFlags
0x08LE_GAP_AD_TYPE_LOCAL_NAME_SHORTShortened Local Name
0x09LE_GAP_AD_TYPE_LOCAL_NAME_COMPLETEComplete Local Name
0x1BLE_GAP_AD_TYPE_ADDRESSLE Bluetooth Device Address
0x1CLE_GAP_AD_TYPE_ROLELE Role

The following advertisement types are system-reserved and are not allowed if the advertisement is used with the Microsoft Bluetooth driver:

Data TypeConstant (wclUUIDs}Description
0x02LE_GAP_AD_TYPE_SERVICES_16_MOREIncomplete List of 16-bit Service UUIDs
0x03LE_GAP_AD_TYPE_SERVICES_16_ALLComplete List of 16-bit Service Class UUIDs
0x04LE_GAP_AD_TYPE_SERVICES_32_MOREIncomplete List of 32-bit Service UUIDs
0x05LE_GAP_AD_TYPE_SERVICES_32_ALLComplete List of 32-bit Service Class UUIDs
0x06LE_GAP_AD_TYPE_SERVICES_128_MOREIncomplete List of 128-bit Service UUIDs
0x07LE_GAP_AD_TYPE_SERVICES_128_ALLComplete List of 128-bit Service Class UUIDs
0x0ALE_GAP_AD_TYPE_TXPOWERTx Power Level
0x0DLE_GAP_AD_TYPE_CODClass of Device
0x0ELE_GAP_AD_TYPE_PAIRING_HASH_CSimple Pairing Hash C192
0x0FLE_GAP_AD_TYPE_PAIRING_RAND_RSimple Pairing Randomizer R192
0x10LE_GAP_AD_TYPE_DEVICE_IDSecurity Manager TK Values
0x11LE_GAP_AD_TYPE_SM_OOB_FLAGSSecurity Manager Out-of-Band Flags
0x12LE_GAP_AD_TYPE_CON_INTERVALSSlave Connection Interval Range
0x17LE_GAP_AD_TYPE_PUBLIC_TARGET_ADDRESSPublic Target Address
0x18LE_GAP_AD_TYPE_RANDOM_TARGET_ADDRESSRandom Target Address
0x19LE_GAP_AD_TYPE_APPEARANCEAppearance
0x1ALE_GAP_AD_TYPE_ADV_INTERVALAdvertising Interval
0x1DLE_GAP_AD_TYPE_PAIRING_HASH_C_256Simple Pairing Hash C256
0x1ELE_GAP_AD_TYPE_PAIRING_RAND_R_256Simple Pairing Randomizer R256
0x3DLE_GAP_AD_TYPE_3D_INFO3D Information Data

Extended Advertisement

If your hardware supports Bluetooth 5 and above, Bluetooth Framework allows you to enable the Extended Advertisement Format when used with Microsoft Bluetooth drivers on Windows 10 and above. The Extended Advertisement Format can be enabled by setting the UseExtendedAdvertisement property of the Bluetooth LE Advertiser. When this property is set to True, the three additional properties are used during advertisement:

  • Anonymous
    If set to True, the device address is not included in the advertisement header.
  • IncludeTxRssi
    If set to True, the transmit power level is included in the advertisement header.
  • PrefferedTxRssi
    If enabled (to disable, set the property's value to -127), requests that the radio use the indicated transmit power level for the advertisement.

If your application enables the Extended Advertisement by setting the UseExtendedAdvertisement property to True but your hardware or OS does not support this feature, the WCL_E_BLUETOOTH_LE_EXT_ADV_NOT_SUPPORTED error will be returned when an application starts the advertisement.