NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
Nominal frame number
Frame
interval where
Value of
FNUM[3:0]
Number
of frames
time interval added (ms)
time added
Minimum
Maximum
189
3
4
4
5
3 - 4
4 - 5
3
4
252
5
6
5 - 6
5
315
6
7
6 - 7
6
378
7
8
7 - 8
7
441
8
9
8 - 9
8
504
9
10
11
12
13
14
15
16
9 - 10
10 - 11
11 - 12
12 - 13
13 - 14
14 - 15
15 - 16
9
567
10
11
12
13
14
15
10
11
12
13
14
15
630
693
756
819
882
945
15.4 RFM in STOP1 mode
The entire RF transmitter digital section can remain powered up, if enabled by the RFEN
bit (see Section 7.3 "Computer Operating Properly (COP) Watchdog"), when the MCU
goes into the STOP1 mode.
15.5 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.
15.5.1 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 42.
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 43. 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.
15.5.2 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
FXTH87ERM
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Reference manual
Rev. 5.0 — 4 February 2019
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