NXP Semiconductors
FXTH87E
FXTH87E, Family of Tire Pressure Monitor Sensors
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 44. 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 45. 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.
15.5.3 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.
low
bit
high
bit
FSK = f
+
-
f
f
OOK = f
RF
RF
FSK = f
OOK = OFF
RF
bit time
bit time
Consecutive “0
data bits
Consecutive “1
data bits
“001101
data bits
aaa-028035
Figure 42.ꢀManchester data bit encoding (POL = 0)
ꢁ
FXTH87ERM
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Reference manual
Rev. 5.0 — 4 February 2019
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