User's Manual

Enhanced Class 1 Bluetooth v2.1 Module
User’s Guide
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75
CONN-GUIDE-BT740_v0.2
Command Packet
Offset
Field
Value
Comments
2
COMMAND
[CMD_RSSI_LINKQUAL]
3
FLOW_IN
??
Runtime value
4..9
BDADDR[]
Nap[0,1]:Uap[2]:Lap[3,4,5]
Bluetooth addr
Response Packet
Offset
Field
Value
Comments
0
LENGTH
Fixed
1
CHANNEL
0
Fixed
2
COMMAND
[CMD_RSSI_LINKQUAL]
3
FLOW_OUT
??
Runtime value
4
STATUS
As appropriate
5..10
BDADDR[]
Nap[0,1]:Uap[2]:Lap[3,4,5]
Bluetooth addr
11
RSSI
-128 to 127
RSSI value. Is zero if the signal is within the
golden range
12
LINKQUAL
0 – 255
The definitions of RSSI and LINKQUAL are paraphrased from the Bluetooth specification as follows:
8.12.1.1 RSSI
This value is the difference between the measured Received Signal Strength Indication (RSSI) and the
limits of the Golden Receive Power Range (see Golden Receive Power Range). Any positive RSSI value
returned by the Host Controller indicates how many dB the RSSI is above the upper limit; any negative
value indicates how many dB the RSSI is below the lower limit. A value of zero indicates that the RSSI is
inside the Golden Receive Power Range.
Note: How accurate the dB values are depends on the Bluetooth hardware. The only requirements for
the hardware are that the Bluetooth device is able to tell whether the RSSI is inside, above or
below the Golden Device Power Range.
8.12.1.2 Golden Receive Power Range
The lower threshold level of the golden receive power range corresponds to a received power between -
56 dBm and 6 dB above the actual sensitivity of the receiver. The upper threshold level is 20 dB above
the lower threshold level to an accuracy of +/- 6 dB.
8.12.1.3 Link Quality
Link_Quality is a value from 0-255, which represents the quality of the link between two Bluetooth devices.
The higher the value, the better the link quality. Each Bluetooth module vendor determines how to
measure the link quality.
In the case of CSR, this value is a measure of BER (Bit Error Rate).