User's Manual

85
www.lairdtech.com
Laird Technologies
BTM510/511
Bluetooth
®
Multimedia Module
6. UUIDs in “CONNECT”/”NO CARRIER” Messages
In proles where functionality and command set differs between both possible roles (asynchronous
proles), role indicating UUIDs are used in the “CONNECT” and “NO CARRIER” messages. HSP and
HFP are asynchronous proles.
A2DP and AVRCP are treated as synchronous proles because only one prole instance with one role
selected can be initialised currently. Therefore, a common UUID is used indicating the prole only, but
not the role.
In a message “CONNECT <bd_addrhex>,<UUID>”, UUID is the prole/role the connection is made to.
Hence for an outgoing connection, UUID indicates the remote device’s prole/role. If it is an incoming
connection, UUID indicates the local device’s prole/role UUID. Hence, role indicating UUIDs presented
in a “CONNECT” message will be equal on both ends of a connected pair.
In a message “NO CARRIER <UUID>”, UUID represents the local prole/role UUID. Hence for an
asynchronous prole, role-indicating UUIDs will differ on both ends of a previously connected pair.
Table 3.64 Gives an overview of currently used UUIDs on BTM devices.
UUID (hex) Prole/Role Role indication Comment
1101 SPP No Synchronous prole
1108 HSP – HS Yes Headset role (Headset prole)
110D A2DP No Common UUID for source and sink role
110E AVRCP No Common UUID for controller and target role
1112 HSP – AG Yes Audio gateway role (Headset prole)
111E HFP – HF Yes Hands-free role (Hands-free prole)
111F HFP – AG Yes Audio gateway role (Hands-free prole)
Table 3.64: UUIDs used in BTM5xx CONNECT/NO CARRIER messages
There is an option to append a direction indicator to a connect message. This enables the host to
distinguish an incoming connection from an outgoing connection based on the “CONNECT“ message.
The direction indicator only applies to role indicating UUIDs and if S329=0. The direction indicator is
congured by S register 331, please refer to Table 3.65.
S331 Meaning Example
Incoming connection Outgoing connection
0 Disabled CONNECT
0123456789AB,1108
CONNECT
0123456789AB,1108
1 Character style, ‘I’ or ‘O’ CONNECT
0123456789AB,1108,I
CONNECT
0123456789AB,1108,O
2 (default) Symbol style, ‘<’ or ‘>’ CONNECT
0123456789AB,1108,<
CONNECT
0123456789AB,1108,>
Table 3.65: Examples for direction indication in “CONNECT” messages
7. Page Scan / Inquiry Scan Interval and Window
Page scanning means being connectable. Inquiry scanning means being discoverable. With the following
S registers the power consumption of the BTM can be inuenced. However, lower power consumption
means longer connection establishment time and longer time until a BTM is discovered by other devices.
The page scan window denes the time for the module to look out for incoming connection requests
(paging). The inquiry scan window denes the time for the module to look out for incoming inquiry
requests (device discovery). If the module is both connectable and discoverable (512=4 or AT+BTP
issued), it will mutually do page scanning and inquiry scanning as shown in Figure 3.33. If connectable
only, the module will perform page scanning only (repeatedly) and if discoverable only, then the module
will perform page scanning only.
S register 508 denes the page scan interval in ms, range is [11..2250].
S register 509 denes the page scan window in ms, range is [11..2250].
S register 510 denes the inquiry scan interval in ms, range is [11..2250].
S register 511 denes the inquiry scan window in ms, range is [11..2250].
AT COMMAND SET
REFERENCE