FXTH870xD
Sensors
Freescale Semiconductor, Inc.
117
13.4
RFM in STOP1 Mode
The entire RF transmitter digital section can remain powered up, if enabled by the RFEN bit (see
), when the MCU
goes into the STOP1 mode.
13.5
Data Encoding
The CODE[1:0] control bits select either Manchester, Bi-Phase, NRZ or MCU direct data encoding of each data bit being
transferred from the RF data buffer to the RF output stage. Further, the polarity of the selected encoding method can be inverted
using the POL control bit.
13.5.1
Manchester Encoding
When the CODE[1:0] bits are both clear the data is Manchester encoded format, with data transmitted as a transition in voltage
occurring in the middle of the bit time. The polarity of this transition is selected by the POL bit. When the POL bit is cleared, then
a logical LOW is defined as an increase in signal in the middle of a bit time and a logical HIGH is defined as a decrease in signal
in the middle of a bit time as shown in
Figure 94
. When the POL bit is set, then a logical LOW is defined as an decrease in signal
in the middle of a bit time and a logical HIGH is defined as a increase in signal in the middle of a bit time as shown in
Figure 95
.
Since there is always a transition in the middle of the bit time there must also be a transition at the start of a bit time if consecutive
“1” or “0” data are present.
13.5.2
Bi-Phase Encoding
When the CODE[1:0] bits are 0:1 then the data is Bi-Phase encoded format, with data transmitted as the presence or absence
of a transition in signal in the middle of the bit time. The polarity of this transition is selected by the POL bit. Unlike Manchester
coding there is always a signal transition at the boundaries of each bit time. When the POL bit is cleared, then a logical HIGH is
defined as no change in signal in the middle of a bit time and a logical LOW is defined as a change in the signal in the middle of
a bit time as shown in
Figure 96
. When the POL bit is set, then a logical HIGH is defined as a change in signal in the middle of
a bit time and a logical LOW is defined as no change in the signal in the middle of a bit time as shown in
Figure 97
. Since there
is always a transition at the ends of the bit time consecutive bits of the same state may have two signal states (high or low) during
the middle of the bit time.
13.5.3
NRZ Encoding
When the CODE[1:0] bits are 1:0 then the data is NRZ encoded format, with data transmitted as either a high or low for the
complete bit time. The polarity of this state is selected by the POL bit. The Manchester and Bi-Phase encoding can actually be
created using NRZ encoding running at twice the desired data rate.
9
10
9 - 10
9
567
10
11
10 - 11
10
630
11
12
11 - 12
11
693
12
13
12 - 13
12
756
13
14
13 - 14
13
819
14
15
14 - 15
14
882
15
16
15 - 16
15
945
Table 72. Frame Number Interval Times (continued)
Value of
FNUM[3:0]
Number of
Frames
Frame Interval Where
Time Added
Nominal Frame Number Time Interval Added (ms)
Minimum
Maximum
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