Infineon Technologies TC1784, User Manual

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TC1784
General Purpose Timer Array (GPTA
®
v5)
User´s Manual 21-46 V1.1, 2011-05
GPTA
®
v5, V1.14
Figure 21-33 The Core Observation Window
A comparison of the previous figures shows that the position of the observation window
with respect to T is dependent on the value of T itself. That means the user, before
updating the comparator with T, needs to calculate the observation window as a function
of T. To avoid this calculation, a
core observation window can be defined that is
independent of T. It will always be centered on T, whatever its value. However, one
particularity exists when using the core observation window: the size of the core
observation window varies depending on two static values: the timer period and the
comparator window’s sizes. In particular, the core observation window reduces as the
value of the timer period is just after a power of 2. This is shown in
Figure 21-34 .
For any timer period (whatever the range) and any threshold position, a symmetrical core
observation window of a statically defined size can be determined.
Figure 21-34 Core Observation Window Sizes Versus Period Sizes
MCT05942
Core Observation Window
T
Before After
Comparator Window = 2 × 2
k
Period is not a power of 2
M
m
Period = M - m + 1
MCT05943
1 2 4 8 16 32
Period
Observation Window
Core Observation Window
Width of Core
Observation Window =
2 x (period - 2
k
)
Condition:
2
k
< period
≤
2 × 2
k