LLCC68 datasheet(92/111 Pages) SEMTECH

92 / 111 page

LLCC68

Data Sheet

Rev. 1.1

DS.LLCC68.W.APP

Dec 2024

92 of 111

Semtech

LLCC68

www.semtech.com

13.4.7 SetCadParams

The command SetCadConfig(...) defines the number of symbols on which CAD operates.

The number of symbols used is defined in the following table.

Parameters cadDetPeak and cadDetMin 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 and Bandwidth, but also depend on the number of symbols used to validate or not

the detection. Choosing the right value is not easy and the values selected must be carefully tested to ensure a good detection at sensitivity

level, and also to limit the number of false detections. Application note AN1200.48 provides guidance for the selection of these parameters.

The parameter cadExitMode defines the action to be done after a CAD operation. This is optional.

The parameter cadTimeout is only used when the CAD is performed with cadExitMode = CAD_RX. Here, the cadTimeout indicates the time

the device stays in Rx following a successful CAD.

Rx Timeout = cadTimeout * 15.625

Table 13-71: SetCadParams SPI Transaction

Byte

5-7

Data from host

Opcode = 0x88

cadSymbolNum

cadDetPeak

cadDetMin

cadExitMode

cadTimeout(23:0)

Table 13-72: CAD Number of Symbol Definition

cadSymbolNum

Value

Number of Symbols used for CAD

CAD_ON_1_SYMB

0x00

CAD_ON_2_SYMB

0x01

CAD_ON_4_SYMB

0x02

CAD_ON_8_SYMB

0x03

CAD_ON_16_SYMB

0x04

Table 13-73: CAD Exit Mode Definition

cadExitMode

Value

Operation

CAD_ONLY

0x00

The chip performs the CAD operation in LoRa. Once done and whatever the activity on the channel,

the chip goes back to STBY_RC mode.

CAD_RX

0x01

The chip 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 cadTimeout * 15.625us

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