CEVT1
CEVT2
CEVT3
CEVT4
One−shot
control logic
Stop
CLK
RST
Modulo 4
counter
2
Mod_eq
Stop value (2b)
ECCTL2[STOP_WRAP] ECCTL2[RE−ARM]
ECCTL2[CONT/ONESHT]
0 1 32
2:4 MUX
Basic Operation
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SPNU563A–March 2018
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Enhanced Capture (eCAP) Module
33.2.2.3 Continuous/One-Shot Control
• The Mod4 (2 bit) counter is incremented via edge qualified events (CEVT1-CEVT4).
• The Mod4 counter continues counting (0->1->2->3->0) and wraps around unless stopped.
• A 2-bit stop register is used to compare the Mod4 counter output, and when equal stops the Mod4
counter and inhibits further loads of the CAP1-CAP4 registers. This occurs during one-shot operation.
The continuous/one-shot block controls the start/stop and reset (zero) functions of the Mod4 counter via a
mono-shot type of action that can be triggered by the stop-value comparator and re-armed via software
control.
Once armed, the eCAP module waits for 1-4 (defined by stop-value) capture events before freezing both
the Mod4 counter and contents of CAP1-4 registers (time-stamps).
Re-arming prepares the eCAP module for another capture sequence. Also re-arming clears (to zero) the
Mod4 counter and permits loading of CAP1-4 registers again, providing the CAPLDEN bit is set.
In continuous mode, the Mod4 counter continues to run (0->1->2->3->0, the one-shot action is ignored,
and capture values continue to be written to CAP1-4 in a circular buffer sequence.
Figure 33-5. Continuous/One-shot Block
33.2.2.4 32-Bit Counter and Phase Control
This counter provides the time-base for event captures, and is clocked via the system clock.
A phase register is provided to achieve synchronization with other counters, via a hardware and software
forced sync. This is useful in APWM mode when a phase offset between modules is needed.
On any of the four event loads, an option to reset the 32-bit counter is given. This is useful for time
difference capture. The 32-bit counter value is captured first, then it is reset to 0 by any of the LD1-LD4
signals.
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