RFM95 Datasheet, PDF (111/121 Pages) List of Unclassifed Manufacturers – Low Power Long Range Transceiver Module

WIRELESS & SENSING
RFM95/96/97/98(W)
PRELIMINARY
DATASHEET
7.3.1.2. Sequencer Configuration
The following graph shows Listen mode - Wake on PreambleDetect state machine:
State Machine
Sequencer Off
&
Initial mode = Sleep or Standby
Start bit set
IdleMode = 1 : Sleep
Start
LowPower
Selection
FromStart = 00
LowPowerSelection = 1
Idle
On T1
FromIdle = 1
On T2
On PreambleDetect
Receive ^{FromReceive = 110} Sequencer Off
Figure 47. Wake On PreambleDetect State Machine
This example configuration is achieved as follows:
Table 90 Listen Mode with PreambleDetect Condition Settings
Variable
IdleMode
FromStart
LowPowerSelection
FromIdle
FromReceive
Effect
1: Sleep mode
00: To LowPowerSelection
1: To Idle state
1: To Receive state on T1 interrupt
110: To Sequencer Off on PreambleDetect interrupt
T_Timer2 defines the maximum duration the chip stays in Receive mode as long as no Preamble is detected. In order to
optimize power consumption, Timer2 must be set just long enough for Preamble detection.
T_Timer1 + T_Timer2 defines the cycling period, i.e. time between two Preamble polling starts. In order to optimize average
power consumption, Timer1 should be relatively long. However, increasing Timer1 also extends packet reception duration.
In order to insure packet detection and optimize the receiver's power consumption, the received packet Preamble should
be as long as T_Timer1 + 2 x T_Timer2.
An example of DIO configuration for this mode is described in the following table:
Table 91 Listen Mode with PreambleDetect Condition Recommended DIO Mapping
DIO Value
Description
0
01
CrcOk
1
00
FifoLevel
3
00
FifoEmpty
4
11
PreambleDetect – Note: MapPreambleDetect bit should be set.
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