Lr-Fhss Commands; Setmodulationparams; Lrfhssbuildframe; Table 8-22: Setmodulationparams Command - Semtech LR1121 User Manual

8.7 LR-FHSS Commands

8.7.1 SetModulationParams

Command SetModulationParams(...) configures the modulation parameters for the selected modem. Since the
parameters are modem dependent, the description hereafter is valid only for the LR-FHSS modulation.

Table 8-22: SetModulationParams Command

Byte 0
Data from
0x02
Host
Data to Host Stat1
•
BitRate defines the LR-FHSS Bit rate in bits per second. Bitrate in bits/s is Bitrate(30:0)/256, with Bitrate(31) =1. For
example, 488.28215Hz bit rate will be coded Bitrate=125000 with Bitrate(31) =1.
In the current LR-FHSS implementation, only 488.28215 Hz is supported, other values are RFU.
•
PulseShape defines the filtering applied to the LR-FHSS packet:
0x0B: Gaussian BT 1. Other values are RFU


8.7.2 LrFhssBuildFrame

Command LrFhssBuildFrame(...) encodes the given payload and configures the internal hopping table

Table 8-23: LrFhssBuildFrame Command

Byte 0
Data from Host 0x02
Data to Host Stat1
Byte 8
HopSequence
Data from Host
(8)
Data to Host 0
•
HeaderCount: number of Headers for the LR-FHSS packet: 1, 2, 3 or 4
•
CR: configures the Coding Rate:
0x00: CR= 5/6

0x01: CR= 2/3

0x02: CR=1/2

0x03: CR= 1/3

•
ModType: 0=GMSK modulation, 488.28125bps data rate
LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
1 2
BitRate
0x0F
(31:24)
IrqStatus
Stat2
(31:24)
1 2
0x2C HeaderCount
IrqStatus
Stat2
(31:24)
9 10
HopSequence
DeviceOffset
(7:0)
0 0
www.semtech.com
3 4
BitRate BitRate
(23:16) (15:8)
IrqStatus IrqStatus
(23:16) (15:8)
3 4
CR ModType
IrqStatus IrqStatus
(23:16) (15:8)
11 12
Payload[0] Payload[1]
0 0
5
BitRate
PulseShape
(7:0)
IrqStatus
(7:0)
5 6
Grid Hopping
IrqStatus
0
(7:0)
...
... Payload[N]
...
Proprietary & Confidential
6
0
7
BW
0
...
0
80 of 130
Semtech