Bluetooth and WM_DEVICECHANGE Messages
Bluetooth includes specific WM_DEVICECHANGE messages that enable developers to obtain messages when Bluetooth devices undergo status changes. This topic describes how to receive Bluetooth-specific WM_DEVICECHANGE messages and lists Bluetooth-specific messages.
Receiving Bluetooth-specific WM_DEVICECHANGE Messages
To receive WM_DEVICECHANGE messages, a handle to the local radio must first be opened. To do this, use one of the following methods:
- Use the SetupDiGetClassDevs function with the following parameters: (GUID_BTHPORT_DEVICE_INTERFACE, …, DIGCF_PRESENT | DIGCF_DEVICEINTERFACE), then use the SetupDiEnumDeviceInterfaces, SetupDiGetDeviceInterfaceDetail, CreateFile, and the SetupDiDestroyDeviceInfoList functions.
- Use the BluetoothFindFirstRadio, BluetoothFindNextRadio, and BluetoothFindRadioClose functions.
When the Bluetooth radio handle is opened, call the RegisterDeviceNotification function and register for notifications on the handle using DBT_DEVTYP_HANDLE as the devicetype. When registered, the following GUIDs are sent, and the DEV_BROADCAST_HANDLE::dbch_data member is the associated buffer.
Bluetooth-specific Messages
The following table lists Bluetooth-specific WM_DEVICECHANGE messages.
| GUID | BUFFER | Description |
|---|---|---|
| GUID_BLUETOOTH_HCI_EVENT | BTH_HCI_EVENT_INFO | This message is sent when a remote Bluetooth device connects or disconnects at the ACL level. |
| GUID_BLUETOOTH_L2CAP_EVENT | BTH_L2CAP_EVENT_INFO | This message is sent when an L2CAP channel between the local radio and a remote Bluetooth device has been established or terminated. For L2CAP channels that are multiplexers, such as RFCOMM, this message is only sent when the underlying channel is established, not when each multiplexed channel, such as an RFCOMM channel, is established or terminated. |
| GUID_BLUETOOTH_PIN_REQUEST | Not applicable. | This message should be ignored by the application. If the application must receive PIN requests, the BluetoothRegisterForAuthentication function should be used. |
| GUID_BLUETOOTH_RADIO_IN_RANGE | BTH_RADIO_IN_RANGE | This message is sent when any of the following attributes of a remote Bluetooth device has changed: the device has been discovered, the class of device, name, connected state, or device remembered state. This message is also sent when these attributes are set or cleared. |
| GUID_BLUETOOTH_RADIO_OUT_OF_RANGE | BLUETOOTH_ADDRESS | This message is sent when a previously discovered device has not been found after the completion of the last inquiry. This message will not be sent for remembered devices. The BTH_ADDRESS structure is the address of the device that was not found. |
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