CEVT1
CEVT2
CEVT5
FFFFFFFF
CTR[0−31]
00000000
CAPx pin
t
MOD4
CTR
CAP1
CAP2
CAP3
CAP4
Capture registers [1−4]
CEVT3
CEVT4
0
1
2
3
0
1
XX
XX
t
2
XX
t
3
XX
t
4
CTR value at CEVT1
t
1
T
1
T
2
2
3
0
t
5
t
6
t
7
T
3
T
4
T
5
T
6
T
7
T
8
CEVT1
CEVT2
CEVT3
CEVT4
Polarity selection
Application of the ECAP Module
816
SPRUH22I – April 2012 – Revised November 2019
Copyright © 2012–2019, Texas Instruments Incorporated
C28 Enhanced Capture (eCAP) Module
8.7.4 Example 4 - Time Difference (Delta) Operation Rising and Falling Edge Trigger
In
the eCAP operating mode is almost the same as in previous section except Capture events
are qualified as either Rising or Falling edge, this now gives both Period and Duty cycle information, i.e:
Period1 = T
1
+T
2
, Period2 = T
3
+T
4
, …etc Duty Cycle1 (on-time %) = T
1
/ Period1 x 100%, etc Duty Cycle1
(off-time %) = T
2
/ Period1 x 100%, etc
Figure 8-26. Capture Sequence for Delta Mode Time-stamp With Rising and Falling Edge Detect
During initialization, you must write to the active registers for both period and compare. This will then
automatically copy the init values into the shadow values. For subsequent compare updates, during run-
time, only the shadow registers must be used.