Semtech LR1121 - Setpacketparams; Setcad; Table 8-5: Setpacketparams Command; Table 8-6: Setcad Command

LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
68 of 130
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8.3.2 SetPacketParams
Command SetPacketParams(...) configures the parameters of the RF packet for the selected modem. Since the
parameters are modem dependent, the description hereafter is valid only for the LoRa modem.
• PbLengthTX defines the length of the LoRa packet preamble.
 Coded on 2 bytes, from 0x0001 (1) to 0xFFFF (65535). Minimum of 12 with SF5 and SF6, and of 8 for other SF
advised.
• HeaderType defines if the header is explicit or implicit:
 0x00: Explicit header (default)
 0x01: Implicit header
• PayloadLen defines the size of the payload (bytes) to transmit or the maximum size of the payload that the receiver can
accept.
 In explicit header mode:
 0: Reception of any payload length between 0 and 255 bytes allowed.
 N: Reception of any payload length between 1 and N bytes accepted. Payload lengths of 0 or > N are rejected
and result in a HeaderErr IRQ.
 In implicit header mode, PayloadLen configures the exact length of the payload to be transmitted or received.
• CRC defines if the CRC is OFF or ON:
 0x00: OFF
 0x01: ON
• InvertIQ defines if the I and Q signals are inverted.
 0x00: Not inverted
 0x01: Inverted
This command fails if no packet type has been set.
8.3.3 SetCad
Command SetCad(...) activates the CAD feature.
Table 8-5: SetPacketParams Command
Byte 0 1 2 3 4 5 6 7
Data from Host 0x02 0x10
PbLengthTX
(15:8)
PbLengthTX
(7:0)
HeaderType PayloadLen CRC InvertIQ
Data to Host Stat1 Stat2
IrqStatus
(31:24)
IrqStatus
(23:16)
IrqStatus
(15:8)
IrqStatus
(7:0)
0x00 0x00
Table 8-6: SetCad Command
Byte 0 1
Data from Host 0x02 0x18
Data to Host Stat1 Stat2