DW1000 User Manual
© Decawave Ltd 2017
Version 2.12
Page 42 of 242
disabling the feature. Using SNIFF mode causes a reduction in sensitivity depending on the ratio and
durations of the on and off periods.
There are two variations of low power SNIFF mode; these are termed SNIFF and Low duty-cycle SNIFF
described in the sub-sections below. The difference between the two modes is that in SNIFF mode the
DW1000 alternates between the
state (on) and the
(off) state, while in Low duty-cycle SNIFF mode
the IC spends the off time in the
state, transitioning only briefly through the
state. The choice of mode has implications for calculating the Sniff Off time, which is described
below. The Low duty-cycle SNIFF mode will consume less power than SNIFF mode during the off period, but
both consume the same power during the on period. Figure 18 shows a simplified view of the state
transitions during SNIFF mode.
Figure 18: State transitions during SNIFF mode
4.5.1 SNIFF mode
In SNIFF mode the DW1000 alternates between the
(on) and the
(off) states. To enable SNIFF mode
two parameters SNIFF_ONT (sniff on time) and SNIFF_OFFT (the off time) need to be configured in
. The on duration is programmed in units of PAC, (these are described in section
), and must be set to at a minimum value of 2 for functional preamble detection.
The SNIFF_ONT counter automatically adds 1 PAC unit to the total PAC count so the programmed value
Setup RX mode of operation as per normal RX
Configure Sniff Mode On duration in multiples of PACs
(as set in RX mode of operation)
REG:1D[3:0] = SNIFF_ON
Configure Sniff Mode Off duration in uS. After this time
we start to turn on the RX blocks. Allow 5uS for the RX
RF block to be stable.
REG:1D[15:8] = SNIFF_OFF
PAC count =
Sniff on time?
Time count (µs)
= Sniff Off Time?
IDLE
(Sniff Off)
Y
N
N
This loop will continue
until preamble
detection or an RX
end event occurs
RX
(Sniff On)
Set RX_EN
IDLE