RFM92 Datasheet, PDF (116/126 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

RFM92W/93W V3.0
7.3.2. Wake on SyncAddress Interrupt
In another possible scenario, the sequencer polls for a Preamble detection and then for a valid SyncAddress interrupt. If
events occur, the sequencer is switched off and the circuit stays in Receive mode until the user switches modes.
Otherwise, the receiver is switched off until the next Rx period.
7.3.2.1. Timing Diagram
Most of the sequencer running time is spent duty cycling the receiver and idle modes with no wanted signal present. As
shown by the timing diagram in Figure 51, the circuit wakes periodically for a short time, defined by RxTimeout. The circuit
is in a Low Power mode for the rest of Timer1 + Timer2 (i.e. Timer1 + Timer2 - TrxTimeout)
No wanted signal
Idle
Receive
Idle ( Sleep + RC )
Receive
Idle
Timer1
RxTimeout
Timer2
Timer2
Timer1
RxTimeout
Figure 51. Listen Mode with no SyncAddress Detected
Timer1
If a preamble is detected before RxTimeout timer ends the circuit stays in Receive mode and waits for a valid SyncAddress
detection. If none is detected by the end of Timer2, Receive mode is deactivated and the polling cycle resumes, without
any user intervention.
Unwanted Signal
Preamble ( Preamble + Sync = T2 )
Wrong
Word
Payload
Crc
Idle
Timer1 RxTimeout
Receive
Timer2
Idle
Receive
Idle
Timer2
Timer1
RxTimeout
Timer1
Preamble
Detect
Figure 52. Listen Mode with Preamble Received and no SyncAddress
But if a valid Sync Word is detected a SyncAddress interrupt is fired, the Sequencer is switched off and the circuit stays in
Receive mode as long as the user doesn't switch modes.
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