sx1231h Semtech Corporation, sx1231h Datasheet - Page 39

• Manufacturer Part Number: sx1231h
• Description: Low Power Integrated Uhf Transceiver With On-chip +20dbm Pa
• Manufacturer: Semtech Corporation

4.3. Listen Mode
The circuit can be set to Listen mode, by setting ListenOn in RegOpMode to 1 while in Standby mode. In this mode,
SX1231H spends most of the time in Idle mode, during which only the RC oscillator runs. Periodically the receiver is woken
up and listens for an RF signal. If a wanted signal is detected, the receiver is kept on and the data is demodulated.
Otherwise, if a wanted signal hasn't been detected after a pre-defined period of time, the receiver is disabled until the next
time period.
This periodical Rx wake-up requirement is very common in low power applications. On SX1231H it is handled locally by the
Listen mode block without using uC resources or energy.
The simplified timing diagram of this procedure is illustrated in Figure 21.
4.3.1. Timings
The duration of the Idle phase is given by t
by t
programmed in the configuration registers via the serial interface.
Both time periods t
configuration register and are calculated as follows:
where ListenResolX is the Rx or Idle resolution and is independently programmable on three values (64us, 4.1ms or
262ms), whereas ListenCoefX is an integer between 1 and 255. All parameters are located in RegListen registers.
The timing ranges are tabulated in Table 17 below.
Table 17 Range of Durations in Listen Mode
Rev 1 - Oct 2011
ADVANCED COMMUNICATIONS & SENSING
ListenRx
. t
ListenRx
ListenRx
includes the wake-up time of the receiver, described in section 4.2.3. This duration can be
Figure 21. Listen Mode Sequence (no wanted signal is received)
and t
t
ListenRx
ListenResolX
Rx
ListenIdle
01
10
11
t
ListenX
(denoted t
ListenIdle
t
ListenIdle
( ListenCoef = 1 )
=
Min duration
ListenCoef
. The time during which the receiver is on and waits for a signal is given
4.1 ms
0.26 s
64 us
ListenX
Page 39
Idle
in the following text) are fixed by two parameters from the
X
⋅
Listen
( ListenCoef = 255 )
Re
Max duration
solX
16 ms
1.04 s
67 s
t
ListenRx
Rx
SX1231H
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