RFM67W Datasheet, PDF (27/37 Pages) List of Unclassifed Manufacturers – ISM TRANSMITTER MODULE

RFM 67W
7.2. Wake-up Times
When switching between modes, an optimized sequence of events is automatically performed by RFM67W. For example,
in response to the command to enter transmit mode whilst in sleep mode, each intermediate mode is engaged - ensuring
crystal oscillator start-up and PLL lock before transition to transmit mode. External indication of PLL lock is given by the
PLL lock pin (MCU mode only). The PLL lock pin output is only valid whist no data is applied to the DATA pin. The transition
from frequency synthesizer mode to transmit is well defined and a function of bit rate and transmit ramp time, given in FSK
mode by:
TS(μs)
=
5
+
1.25
·
pa_ramp_rising
_time(3:0)
+
------1-------
2 · R_B
where pa_ramp_rising_time(3:0) is the user defined contents of PaFskRamp and R_B is the bit rate. For OOK mode the time
is given by:
T S _TS ( μ s )
=
5 + ------1-------
2 · R_B
A flow chart showing the automatic, optimised start-up procedure, initiated with a single SPI command is shown in
Figure 14. Note that after the PLL lock indicator is set then the transmitter requires TS_TR to set-up before transmission
may begin.
7.3 Reset Pin Timing
Manual reset of the RFM67W is possible by asserting a logical high to the reset pin. The timing for this operation is shown
in the following figure. During the reset operation the RFM67W current consumption may rise to 1 mA. Following the
reset operation the user must wait 5 ms before performing any other operation.
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