RM0440 Rev 4 893/2126
RM0440 High-resolution timer (HRTIM)
1083
27.3.9 External event filtering in timing units
Once conditioned, the 10 external events are available for all timing units.
They can be used directly and are active as soon as the timing unit counter is enabled
(TxCEN bit set).
They can also be filtered to have an action limited in time, usually related to the counting
period. Two operations can be performed:
• blanking, to mask external events during a defined time period,
• windowing, to enable external events only during a defined time period.
These modes are enabled using HRTIM_EExFLTR[3:0] bits in the HRTIM_EEFxR1 and
HRTIM_EEFxR2 registers. Each of the 5 timer A..F timing units has its own programmable
filter settings for the 10 external events.
Blanking mode
In event blanking mode (see Figure 219), the external event is ignored if it happens during a
given blanking period. This is convenient, for instance, to avoid a current limit to trip on
switching noise at the beginning of a PWM period. This mode is active for EExFLTR[3:0]
bitfield values ranging from 0001 to 1100.
Figure 219. Event blanking mode
In event postpone mode, the external event is not taken into account immediately but is
memorized (latched) and generated as soon as the blanking period is completed, as shown
on Figure 220. This mode is enabled by setting EExLTCH bit in HRTIM_EEFxR1 and
HRTIM_EEFxR2 registers.
Figure 220. Event postpone mode
MS32294V1
Ext./int. event
Blanking
External event
Blanking source
Resulting event
MS32295V1
Ext./int. event
Blanking
External event
Blanking source
Resulting event
Latch
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