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www.lairdtech.com
Laird Technologies
BTM520/521
Bluetooth
®
Multimedia Plus Module
CONFIGURING
THE BTM520/521
Table 3-6: A2DP - S-Registers and AT-Commands
TASK
AT-COMMAND / SREGISTER
COMMENT
Set A2DP role
S300 [0..2]
0 = feature not set
1 = A2DP Sink (default)
2 = A2DP Source
Advertise service
S102
128 = A2DP, Error 46 if A2DP role has not
been set (see S300)
Initiate outgoing
A2DP connection
AT+APD<bd_addr>
Response if accepted:
“CONNECT 0123456789012,110D”
Response if rejected:
“NO CARRIER 110D”
close only A2DP connection
“AT+APH” or “ATH110D”
Response:
“NO CARRIER 110D” if connection has
existed and S329=0
“NO CARRIER” if connection has not
existed and S329=0
close all connections
ATH*
Response:
“NO CARRIER <profileUUID>” for each
profile that was previously connected
(see section 3.7.2)
Set gain level
S589 [0..22], default = 15
Set codec output gain level (applies to sink)
S590 [0..22], default = 15
Set codec input gain level (applies to source)
Set overall gain (dBr * 10)
S689 [-450..215]
Set codec output gain in dBr * 10
(applies to sink), default = 0
S690 [-450..215]
Set codec input gain in dBr * 10
(applies to source), default = 0
Set A2DP sink supported
features bit mask
S312 [0..15]
Bitmask - sink supported features:
Bit 0 = Headphone (default)
Bit 1 = Speaker
Bit 2 = Recorder
Bit 3 = Amplifier
Set A2DP source supported
features bit mask
S313 [0..15]
Bitmask - source supported features:
Bit 0 = Player (default)
Bit 1 = Microphone
Bit 2 = Tuner
Bit 3 = Mixer
3. AVRCP
The “Audio/Video Remote Control Profile” is used to remotely control audio or video streaming
devices. A device must be defined as either control or target. Furthermore, one of four categories
(Player/Recorder, Monitor/Amplifier, Tuner, Menu) has to be assigned to a device.
The AVRCP specification [5] adopts the AV/C Digital Interface Command Set (AV/C command set,
defined by the 1394 Trade Association) device model and control message format. In this device
model a remote control target consists of one or more subunits. At least the subunit ”PANEL”
must exist. Remote control commands are passed to a subunit with the “PASS THROUGH”
command. A BT-MM+ Module, configured as target will support one PANEL subunit.
3.1 AVRCP - Control (CT)
This section describes AT Commands and S registers used when BT-MM+ is configured as
an AVRCP Controller (S301=1).
