DVK-BTM521 Laird Technologies, DVK-BTM521 Datasheet - Page 42

• Manufacturer Part Number: DVK-BTM521
• Description: BT MM DEV KIT
• Manufacturer: Laird Technologies
• Type: Transceiver, Bluetoothr

Specifications of DVK-BTM521

• Frequency: 2.4GHz
• Interface Type: RS-232
• Processor Series: BTM521
• Silicon Manufacturer: Laird Technologies
• Kit Application Type: Communication & Networking
• Application Sub Type: Bluetooth
• Kit Contents: Development Board & Software Tools
• Features: Supports CSR
• Rohs Compliant: Yes
• For Use With/related Products: BTM521
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: DVK-BTM521

BTM520/521
Bluetooth
AT COMMAND SET
REFERENCE
42 www.lairdtech.com
®
Multimedia Plus Module
4. Set A2DP Device Class
ATS515=$<device_class
For compliance with the A2DP specification, [2] (and hence for successful interoperability to other
devices) it is required to set up a valid device class code. The default device class code of a BTM device
is 0x001F00 which is invalid for the A2DP profile.
The A2DP specification [2] mandates the following requirements for the device class of an A2DP device:
1. Mandatory to set the ‘Rendering’ bit for the SNK and the ‘Capturing’ bit for the SRC in the Service
Class field.
2. Recommended to set ‘Audio/Video’ as Major Device class both for the SNK and the SRC.
3. Select the appropriate Minor Device class as defined in the Bluetooth Assigned Numbers [8].
There is a tool available on the internet for creating a particular device class code: refer to [9].
With the assumptions above (Major Device class = Audio/Video), Table 8 in [8] gives the complete list
of codes for the minor device class. If you are not sure about the minor device class, use the row
marked with n/a for the minor device (e.g., 0x040400 for sink or 0x080400 for source).
Table 3.15 gives some examples of device class codes for A2DP devices.
The device class is written to the module using ATS515=$<device_class
is the 6 character device class code without leading “0x”. Use subsequent AT&W and ATZ for the new
value to become effective. Please also refer to page 15, section 4.
4.1 Initiate A2DP Connection
AT+APD<bd_addr
Initiate A2DP connection to Bluetooth address <bd_addr
complementary role to the local device. If link keys are missing in one or both devices, pairing
will either occur automatically or pairing is required to be initiated by AT+BTW<bd_addr
This depends on various factors like the combination of local and remote IO capabilities or the
Bluetooth version of the remote device.
Response:
<cr><lf>PAIR 0 <bd_addr> 00<cr><lf>
<cr><lf>CONNECT <bd_addr>,110D,><cr><lf>
Or:
<cr><lf>NO CARRIER 110D<cr><lf>
Device Class Code Major Service
0x040400
0x040414
0x040418
0x04041C
0x040420
0x080400
0x080410
0x080428
hex
hex
Table 3.15: A2DP device class code – examples
>
Rendering
Rendering
Rendering
Rendering
Rendering
Capturing
Capturing
Capturing
>; AT&W; ATZ
Major Device
Audio/Video
Audio/Video
Audio/Video
Audio/Video
Audio/Video
Audio/Video
Audio/Video
Audio/Video
(first time only, auto pairing without MITM authent.)
(not successful)
Minor Device
n/a
Loudspeaker
Headphones
Portable Audio
Car audio
n/a
Microphone
HiFi Audio Device Source
hex
>. The remote device must support the
hex
> where <device_class
A2DP Role
Sink
Sink
Sink
Sink
Sink
Source
Source
Laird Technologies
hex
>.
hex
>