RF65 datasheet(33/72 Pages) ETC2

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RF65

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ADVANCED COMMUNICATIONS & SENSING

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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.

tListenIdle

Idle

time

tListenRx

Figure 17. Listen Mode Sequence (no wanted signal is received)

4.3.1. Timings

The duration of the Idle phase is given by tListenIdle. The time during which the receiver is on and waits for a signal is given

by tListenRx. tListenRx 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 tListenRx and tListenIdle (denoted tListenX in the following text) are fixed by two parameters from the

configuration register and are calculated as follows:

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

Min duration

( ListenCoef = 1 )

Max duration

( ListenCoef = 255 )

64 us

16 ms

4.1 ms

1.04 s

0.26 s

67 s

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