Semtech LR1121 - Setcadparams; Setlorasynchtimeout; Table 8-7: Setcadparams Command; Table 8-8: Cadexitmode Parameter

LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
69 of 130
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8.3.4 SetCadParams
Command SetCadParams(...) defines the LoRa CAD parameters.
• SymbolNum defines the number of symbols used for the CAD detection.
• DetPeak and DetMin define the sensitivity of the LoRa modem when trying to correlate to actual LoRa preamble
symbols. These two settings depend on the LoRa spreading factor, the Bandwidth, and the number of symbols used to
validate the detection. Choosing the right value must be carefully tested to ensure a good detection at sensitivity level,
and also to limit the number of false detections.
• CadExitMode defines the action to be performed after a CAD operation.
• Timeout is only used when the CAD is performed with cadExitMode = CAD_RX or CAD_LBT.
 If cadExitMode = CAD_RX, see 7.2.2 SetRx for Timeout definition
 If cadExitMode = CAD_LBT, see 7.2.3 SetTx for Timeout definition
8.3.5 SetLoRaSynchTimeout
Command SetLoRaSynchTimeout(...) configures the LoRa modem to issue an RX timeout after exactly SymbolNum
symbols if no packet was detected by then.
• SymbolNum: 0x00: No timeout (default value)
Table 8-7: SetCadParams Command
Byte 0 1 2 3 4 5 6 7 8
Data from Host 0x02 0x0D
Symbol
Num
DetPeak DetMin
CadExit
Mode
Timeout
(23:16)
Timeout
(15:8)
Timeout
(7:0)
Data to Host Stat1 Stat2
IrqStatus
(31:24)
IrqStatus
(23:16)
IrqStatus
(15:8)
IrqStatus
(7:0)
0x00 0x00 0x00
Table 8-8: CadExitMode Parameter
Value CadExitMode Operation
0x00 CAD_ONLY
The chip performs a CAD operation in LoRa. Once done and whatever the activity on the channel, the
device goes back to STBY_RC mode.
0x01 CAD_RX
The device performs a CAD operation and if an activity is detected, it stays in RX until a packet is
detected or the timer reaches the timeout defined by
Timeout *31.25us
0x10 CAD_LBT
The device performs a CAD operation and if no activity is detected, it goes into TX mode with the
defined
Timeout as timeout parameter.
Table 8-9: SetLoRaSynchTimeout Command
Byte 0 1 2
Data from Host 0x02 0x1B SymbolNum
Data to Host Stat1 Stat2 IrqStatus (31:24)