Semtech LR1121 - Setrxdutycycle; Table 7-6: Setrxdutycycle Command

LR1121
User Manual Rev 1.1
UM.LR1121.W.APP Mar 2023
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7.2.6 SetRxDutyCycle
Command SetRxDutyCycle(...) periodically opens RX windows. Between RX windows, the device goes in Sleep mode
(with retention). The clock source for the RTC has to be configured with a command before entering Duty Cycle mode.
• RxPeriod defines the maximum RX window duration, expressed in periods of the 32.768kHz RTC. The maximum Delay
value corresponds to 512s.
• SleepPeriod defines the duration of the Sleep period between the RX windows. It is expressed in periods of the
32.768kHz RTC. The maximum Delay value corresponds to 512s.
• Mode selects the device mode during the RX windows:
0: Configures the device in RX mode during RX windows. Available for (G)FSK and LoRa packet types.
1: Configures the device in CAD mode during RX windows. Available only for LoRa packet types. Returns CMD_FAIL
for (G)FSK packet types.
The Mode parameter is optional, and is set to 0 if not sent.
When this command is sent in Standby mode, the context (device configuration) is saved and the device enters in a loop
defined by the following steps, and depicted in Figure 7-2: LR1121 Current Profile During RX Duty Cycle Operation .
1. The device enters RX and listens for an incoming RF packet for a period of time defined by RxPeriod.
2. Upon preamble detection, the timeout is stopped and restarted with the value 2 * RxPeriod + SleepPeriod, as shown in
Figure 7-3: RX Duty Cycle Upon Preamble Detection.
3. If no packet is received during the RX window, the device goes into Sleep mode with context saved for a period of time
defined by SleepPeriod.
4. At the end of the Sleep window, the device automatically restarts the process of restoring context and enters the RX
mode, and so on. At any time, the host can stop the procedure.
The loop is terminated if either:
• A packet is detected during the RX window, at which moment the chip interrupts the host via the RX_DONE flag and
returns to the configured Fallback mode (refer to Section 7.2.5 "SetRxTxFallbackMode " on page 52 ).
• The host issues a SetStandby(...) command during the RX window.
• The device is woken up from Sleep mode with a falling edge of NSS. In this case, the user should send the
SetStandby(...) command to avoid race conditions if the NSS falling edge was issued during the boot phase.
If an RxDutyCycle(...) is started, AutoRxTx or SetRxTxFallback modes are not used.
StopTimeoutOnPreamble(...) has no effect on this mode.
Note: The RxDutyCycle(...) command returns CMD_FAIL in the next command status if the packet type has not been set.
Table 7-6: SetRxDutyCycle Command
Byte 0 1 2 3 4 5 6 7 8
Data from Host 0x02 0x14
RxPeriod
(23:16)
RxPeriod
(15:8)
RxPeriod
(7:0)
Sleep
Period
(23:16)
Sleep
Period
(15:8)
Sleep
Period
(7:0)
Mode
Data to Host Stat1 Stat2
IrqStatus
(31:24)
IrqStatus
(23:16)
IrqStatus
(15:8)
IrqStatus
(7:0)
0x00 0x00 0x00