Semtech LR1121 - Commands; Setrffrequency; Setrx; Table 7-1: Setrffrequency Command

LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
49 of 130
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7.2 Commands
7.2.1 SetRfFrequency
Command SetRfFrequency(...) sets the RF (PLL) frequency of the radio. In RX mode, the frequency is internally
down-converted to IF Frequency.
• RfFreq: RF Frequency of the radio in Hz. All frequency dependent parameters are automatically recomputed by the
LR1121 firmware when processing this command.
7.2.2 SetRx
Command SetRx(...) sets the sub-GHz radio in RX mode. The sub-GHz path is selected for RfFreq frequencies below or
equal to 1.50GHz. Above this value the HF path is selected. If no packet is received after the defined RxTimeout, the device
goes back to Standby RC mode.
• RxTimeout is expressed in periods of the 32.768kHz RTC. The maximum timeout value corresponds to 512s. Values
0x000000 and 0xFFFFFF disable the timeout function.
 0x000000 sets the device in RX mode until a reception occurs. After packet reception, the device returns to Standby
mode.
 0xFFFFFF sets the device in RX mode until the host sends a command to change the mode. The device can receive
several packets. Each time a packet is received, a packet done indication is given to the host and the device
automatically searches for a new packet.
If the timer is active, the radio stops the reception at the end of the timeout period, unless a preamble or a Header has been
detected as defined by the StopTimeoutOnPreamble configuration.
If no packet type was configured, or the packet type does not allow RX operations, this command fails.
The BUSY signal goes low after the device is set into RX mode.
Table 7-1: SetRfFrequency Command
Byte 0 1 2 3 4 5
Data from Host 0x02 0x0B
RfFreq
(31:24)
RfFreq
(23:16)
RfFreq
(15:8)
RfFreq
(7:0)
Data to Host Stat1 Stat2
IrqStatus
(31:24)
IrqStatus
(23:16)
IrqStatus
(15:8)
IrqStatus
(7:0)
Table 7-2: SetRx Command
Byte 0 1 2 3 4
Data from Host 0x02 0x09 RxTimeout (23:16) RxTimeout (15:8) RxTimeout (7:0)
Data to Host Stat1 Stat2 IrqStatus (31:24) IrqStatus (23:16) IrqStatus (15:8)