The features of the eCAP module include:
- Speed measurements of rotating machinery (for example, toothed sprockets sensed
by way of Hall sensors)
- Elapsed time measurements between position sensor pulses
- Period and duty cycle measurements of pulse train signals
- Decoding current or voltage amplitude derived from duty cycle encoded current/voltage sensors
The eCAP module features described in this chapter
include:
- 4-event time-stamp registers (each 32 bits)
- Edge polarity selection for up to four sequenced time-stamp capture events
- Interrupt on either of the four events
- Single-shot capture of up to four event time-stamps
- Continuous mode capture of time stamps in a four-deep circular buffer
- Absolute time-stamp capture
- Difference (Delta) mode time-stamp capture
- When not used in capture mode, the eCAP module can be configured as a single-channel PWM output
The capture
functionality of the Type 1 eCAP is enhanced from the Type 0 eCAP
with the following added features:
- Event
filter reset bit
- Writing a 1 to ECCTL2[CTRFILTRESET] clears the
event filter, the modulo counter, and any pending
interrupts flags. Resetting the bit is useful for
initialization and debug.
- Modulo
counter status bits
- The modulo counter (ECCTL2 [MODCNTRSTS])
indicates which capture register is loaded next.
In the Type 0 eCAP, to know the current state of
the modulo counter was not possible
- DMA trigger source
- eCAPxDMA was added as a DMA trigger. CEVT[1-4]
can be configured as the source for eCAPxDMA.
- Input
multiplexer
- ECCTL0 [INPUTSEL] selects one of 128 input
signals, which are detailed in Section 24.3.
- EALLOW
protection
- EALLOW protection was added to critical
registers. To maintain software compatibility with Type-0,
configure DEV_CFG_REGS.ECAPTYPE to make these
registers unprotected.
The capture
functionality of the Type 2 eCAP is enhanced from the Type 1 eCAP
with the following added features:
- Added ECAPxSYNCINSEL register
- ECAPxSYNCINSEL register is
added for each eCAP to select an external SYNCIN.
Every eCAP can have a separate SYNCIN signal.