LLCC68 datasheet(80/106 Pages) SEMTECH

80 / 106 page

LLCC68

Data Sheet

Rev. 1.0

DS.LLCC68.W.APP

July 2019

80 of 106

Semtech

www.semtech.com

13.4.5 SetModulationParams

The command SetModulationParams(...) is used to configure the modulation parameters of the radio. Depending on the

packet type selected prior to calling this function, the parameters will be 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 purpose. The pulse represents the Gaussian filter used to filter the modulation stream on the transmitter side.

In LoRa® packet type, SF corresponds to the Spreading Factor used for the LoRa® modulation. SF is defined by the parameter

Param[1]

. BW corresponds to the bandwidth onto which the LoRa® signal is spread. BW in LoRa® is defined by the parameter

Param[2]

The LoRa® payload is fit with a forward error correcting mechanism which has several levels of encoding. The Coding Rate

(CR) is defined by the parameter Param[3] in LoRa®.

The parameter LdOpt corresponds to the Low Data Rate Optimization (LDRO). This parameter is usually set when the LoRa®

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

Optimization" on page 34.

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 (32 MHz). The bit rate

range is from 600 b/s up to 300 kb/s with a default value at 4.8 kb/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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