RF65 Datasheet, PDF (33/72 Pages) List of Unclassifed Manufacturers – Low Power Integrated UHF Receiver With -120dBm High Sensitivity

ADVANCED COMMUNICATIONS & SENSING
RF65
DATASHEET
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,
RF65 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 RF65 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 17.
t_ListenIdle
Rx
Idle
Rx
time
t_ListenRx
t_ListenRx
Figure 17. Listen Mode Sequence (no wanted signal is received)
4.3.1. Timings
The duration of the Idle phase is given by t_ListenIdle. The time during which the receiver is on and waits for a signal is given
by t_ListenRx. t_ListenRx includes the wake-up time of the receiver, described in section 4.2.1. This duration can be
programmed in the configuration registers via the serial interface.
Both time periods t_ListenRx and t_ListenIdle (denoted t_ListenX in the following text) are fixed by two parameters from the
configuration register and are calculated as follows:
t_ListenX = ListenCoefX ⋅ Listen Re solX
where ListenResolX is the Rx or Idle resolution and is independantly 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 13 below.
Table 13 Range of Durations in Listen Mode
ListenResolX
01
10
11
Min duration
( ListenCoef = 1 )
64 us
4.1 ms
0.26 s
Max duration
( ListenCoef = 255 )
16 ms
1.04 s
67 s
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