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:
- 32 bit time base with 5nS time resolution when sourced with a
200MHz system clock
- 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 Table 7-171.
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.
The capture functionality
of the Type 3 eCAP is enhanced from the Type 2 eCAP with the
following added features:
- Two signal monitoring units to monitor edge, pulse
width, and period
- Signal monitoring can optionally be tightly
coupled with ePWM global load strobes and trip
events
- Increased the number of multiplexed capture inputs from
128 to 256
- DMA event generation capability in PWM mode of
operation
- ADC SOC generation capability, to trigger ADC
conversion