RM0440 Rev 4 891/2126
RM0440 High-resolution timer (HRTIM)
1083
The EExFAST mode is only available with level-sensitive programming (EExSNS[1:0] = 00);
the edge-sensitivity cannot be programmed.
It is possible to apply event filtering to external events (both blanking and windowing with
EExFLTR[3:0] != 0000, see Section 27.3.9). In this case, EExLTCHx bit must be reset: the
postponed mode is not supported, neither the windowing timeout feature.
Note: The external event configuration (source and polarity) must not be modified once the related
EExFAST bit is set.
A fast external event cannot be used to toggle an output: if must be enabled either in
HRTIM_SETxyR or HRTIM_RSTxyR registers, not in both.
When a set and a reset event - from 2 independent fast external events - occur
simultaneously, the reset has the highest priority in the crossbar and the output becomes
inactive.
When EExFAST bit is set, the output cannot be changed during the 11 f
HRTIM
clock periods
following the external event.
Figure 217 and Figure 218 give practical examples of the reaction time to external events,
for output set/reset and counter reset.
Table 223. Output set/reset latency and jitter versus external event operating mode
EExFAST
Response time
latency
Response time jitter
Jitter on output pulse
(counter reset by ext. event)
0
5 to 6 cycles of f
HRTIM
clock
1 cycles of f
HRTIM
clock
No jitter, pulse width maintained with
high-resolution
1
Minimal latency
(depends whether the
comparator or digital
input is used)
Minimal jitter
1 cycle of f
HRTIM
clock jitter pulse width
resolution down to t
HRTIM
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