TC1796
Peripheral Units (Vol. 2 of 2)
General Purpose Timer Array (GPTA)
User’s Manual 24-43 V2.0, 2007-07
GPTA, V2.0
Figure 24-30 Observation and Comparator Windows (timer is a power of 2)
The scalable and signed greater/equal comparator scheme leads to a limitation that
must be considered when programming the GPTA Module. If the timer range is not a
power of 2, the comparator window (always a power of 2) will no longer match the timer
period. This will impact the observation window as described in the following paragraph.
Observation window for reloaded timers (period is not a power of 2)
In that case, the comparator window must exceed the timer period. The user must find
the comparator window (by selecting the scale factor k) which fits best the timer period.
The following equation must apply:
2
k
< Period ≤ 2 × 2
k
(24.1)
Figure 24-31 and Figure 24-32 show that one part of the comparator window must be
discarded in order to avoid inconsistency, resulting in the observation window.
MCT05939
Before After
T
Comparator Window (= 2 × 2
k
)
Observation Window (= Period)
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