Data Sheet

Page 110
RFM95/96/97/98(W)
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Timer2
WIRELESS & SENSING PRELIMINARY DATASHEET
7.3.1.1. Timing Diagram
When no signal is received, the circuit wakes every Timer1 + Timer2 and switches to Receive mode for a time defined by
Timer2, as shown on the following diagram. If no Preamble is detected, it then switches back to Idle mode, i.e. Sleep mode
with RC oscillator on.
Nore ceived sign al




Receive
Idle ( Sleep + RC ) Receive Idle
Timer1
Timer2
Timer1
Timer2
Timer1
Figure 45. Listen Mode with No Preamble Received
If a Preamble signal is detected, the Sequencer is switched off. The PreambleDetect signal can be mapped to DIO4, in
order to request the user's attention. The user can then take appropriate action.
Received sign al


Preamble ( As long as T1 + 2 * T2 )
Sync
Word
Payload Crc
Idle ( Sleep + RC ) Receive
Time r 1
Timer2
Pr eam ble
Detect
Figure 46. Listen Mode with Preamble Received