DCAEVT1
DCFOFFSET[OFFSET]
Sync
Blank
Control
Logic
DCFWINDOW[WINDOW]
DCFCTL[BLANKE, PULSESEL]
DCCAP[15:0] Reg
DCAEVT2
DCBEVT1
DCBEVT2
00
01
10
11
DCFCTL[PULSESEL]
TBCTR(16)
Capture
Control
Logic
CTR = PRD
CTR = 0
TBCLK
CTR=PRD
CTR=Zero
TBCLK
TBCLK
DCEVTFILT
async
DCFCTL[SRCSEL]
1 0
BLANKWDW
DCFCTL[INVERT]
DCCAPCTL[CAPE, SHDWMODE]
ePWM Submodules
2053
SPNU563A – March 2018
Copyright © 2018, Texas Instruments Incorporated
Enhanced Pulse Width Modulator (ePWM) Module
35.2.9.3.2 Event Filtering
The DCAEVT1/2 and DCBEVT1/2 events can be filtered via event filtering logic to remove noise by
optionally blanking events for a certain period of time. This is useful for cases where the analog
comparator outputs may be selected to trigger DCAEVT1/2 and DCBEVT1/2 events, and the blanking
logic is used to filter out potential noise on the signal prior to tripping the PWM outputs or generating an
interrupt or ADC start-of-conversion. The event filtering can also capture the TBCTR value of the trip
event.
shows the details of the event filtering logic.
Figure 35-49. Event Filtering
If the blanking logic is enabled, one of the digital compare events – DCAEVT1, DCAEVT2, DCBEVT1,
DCBEVT2 – is selected for filtering. The blanking window, which filters out all event occurrences on the
signal while it is active, will be aligned to either a CTR = PRD pulse or a CTR = 0 pulse (configured by the
DCFCTL[PULSESEL] bits). An offset value in TBCLK counts is programmed into the DCFOFFSET
register, which determines at what point after the CTR = PRD or CTR = 0 pulse the blanking window
starts. The duration of the blanking window, in number of TBCLK counts after the offset counter expires, is
written to the DCFWINDOW register by the application. During the blanking window, all events are
ignored. Before and after the blanking window ends, events can generate soc, sync, interrupt, and force
signals as before.
shows several timing conditions for the offset and blanking window within an ePWM period.
Notice that if the blanking window crosses the CTR = 0 or CTR = PRD boundary, the next window still
starts at the same offset value after the CTR = 0 or CTR = PRD pulse.