User's Manual

Enhanced Class 1 Bluetooth v2.1 Module
User’s Guide
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CONN-GUIDE-BT740_v0.2
8.17.10 Read Attribute Value
This command is valid for both agent and manager role and reads the value of the attribute specified via
the attribute ID and the qualifier ID. The value returns in HDP data channel 0xB0 formatted as described
below.
Command Packet
Offset
Field
Value
Comments
0
LENGTH
10
Fixed
1
CHANNEL
0
Fixed
2
COMMAND
[CMD_HDP_ATTRIBUTE_READ]
3
FLOW_IN
??
Runtime value
4..5
HANDLE[2]
[4]=msb,[5]=lsb
Handle identifying an
instance of data
specialization
agent/manager combination
6..7
ATTRID[2]
[6]=msb,[7]=lsb
8..9
QUALIFIERID[2]
[8]=msb,[9]=lsb
See Note 1
Response Packet
Offset
Field
Value
Comments
0
LENGTH
8
Fixed
1
CHANNEL
0
Fixed
2
COMMAND
[CMD_HDP_ATTRIBUTE_READ]
3
FLOW_OUT
??
Runtime value
4
STATUS
As appropriate
5
HOSTCONTEXT
XX
This is echoed back from
the command
6..7
HANDLE[2]
[6]=msb,[7]=lsb
Echoed back from the
command
1. For manager role, this is the object ID (MDS=0,NU=1 etc) and for Agent please refer to ‘Section Weigh Scale Data
Specialization’. As more data specializations are added, the qualifierID specifies appropriately for that specialization.
The host shall wait until the response receives before submiting further commands.
If the attribute exists, then the data sends in a Logical HDP data packet transported in one or more physical data
packets over channel 0xB0. The physical packets of incoming data in channel 0xB0 is viewed as a stream of data
making up logical packets.
The logical packet format is as follows and is also addressed in a dedicated section later:
LEN[2],00,HANDLE[2],ATTRID[2],QUALIFIERID[2],DATA[N]
Where LEN[2], HANDLE[2],ATTRID[2],QUALIFIERID[2] are in big endian format (msb sent first) and N is
equal to LEN[2]+9.
The 00 after the LEN[2] field signifies that this logical packet consists of attribute data.