LLCC68 datasheet(84/111 Pages) SEMTECH

84 / 111 page

LLCC68

Data Sheet

Rev. 1.1

DS.LLCC68.W.APP

Dec 2024

84 of 111

Semtech

LLCC68

www.semtech.com

13.4.5 SetModulationParams

The command SetModulationParams(...) configures the modulation parameters of the radio. Depending on the packet type selected

prior to calling this function, the parameters is interpreted differently by the chip.

The meaning of the parameter depends on the selected protocol.

In FSK, bitrate (BR) and Frequency Deviation (Fdev) are used for the transmission or reception. Bandwidth is used for reception purposes.

The pulse represents the Gaussian filter used to filter the modulation stream on the transmitter side.

ModParam[1] defines SF in LoRa packet types, where SF corresponds to the Spreading Factor used for the LoRa modulation.

ModParam[2] defines BW in LoRa, where BW corresponds to the bandwidth onto which the LoRa signal is spread.

ModParam[3] defines Coding Rate (CR) in LoRa. The LoRa payload includes a forward error correcting mechanism which has several levels

of encoding.

ModParam[4] defines the parameter LdOpt which corresponds to the Low Data Rate Optimization (LDRO). This parameter is usually set

when the LoRa symbol time is equal or above 16.38ms but can be used if necessary in other situations. See Section 6.1.1.4 "Low Data Rate

Optimization" on page 36 .

13.4.5.1 GFSK Modulation Parameters

The tables below provide more details on the GFSK modulation parameters:

The bit rate is entered with the parameter br which is related to the frequency of the main oscillator (32MHz). The bit rate range is from

600b/s up to 500kb/s with a default value at 4.8kb/s.

Table 13-42: SetModulationParams SPI Transaction

Byte

Data from host for

Modulation Params

Opcode

0x8B

Mod

Param1

Mod

Param2

Mod

Param3

Mod

Param4

Mod

Param5

Mod

Param6

Mod

Param7

Mod

Param8

Table 13-43: GFSK ModParam1, ModParam2 & ModParam3 - br

BR(23:0)

Description

0x000001 to 0xFFFFFF

br = 32 * Fxtal / bit rate

Table 13-44: GFSK ModParam4 - PulseShape

PulseShape

Description

0x00

No Filter applied

0x08

Gaussian BT 0.3

0x09

Gaussian BT 0.5

0x0A

Gaussian BT 0.7

0x0B

Gaussian BT 1

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