C28x eCAP

When you select eCAP, the block captures and logs pin transitions for each capture unit to a FIFO buffer. When you select APWM, the block generates asymmetric pulse width modulation (APWM) waveforms for driving downstream systems.

Select the required eCAP module to have a dedicated eCAP pin for capturing the external events.

The pin selection for the eCAP module can be done by browsing to Hardware Implementation > Target hardware resources. The selection option is provided only if the module has more than one pin that can be configured for an eCAP module.

This value provides the time base for event captures, clocked by the system clock. A phase register is used to synchronize with other counters via software- or hardware-forced synchronization. For information about software- or hardware-forced synchronization, see Enable counter Sync-In mode parameter. This value is useful in APWM mode when you need a phase offset between capture modules. Set the phase offset to an integer from 0 to 42949667295 (2³²) counts.

Synchronization can be done using the SYNCI event or the software. When synchronization occurs, the shadow register CTRPHS is loaded into the active counter TSCTR in the current eCAP module and the eCAP modules downstream.

A software method for synchronizing one or more eCAP time bases. The synchronization occurs when the synchronization input value is 1.

Dependencies

This parameter appears only when Enable counter Sync-In mode is selected.

Synchronizes an eCAP counter with other eCAP counters. The options are:

Sample time for the block in seconds.

The input signal is prescaled by twice the value of this parameter. For example, if you enter 1, the input is prescaled by 2, and for 31, the input is prescaled by 62. Entering 0 bypasses the input prescaler, leaving the input capture signal unchanged.

Select Enable high resolution capture (HRCAP mode) parameter to capture the pulses in high resolution.

Dependencies

This parameter is available only for specific TI processors.

Select Enable continuous calibration mode parameter to perform the calibration periodically.

If continuous calibration mode is not enabled, then calibration occurs only once (Initialization only). High resolution interrupt is used to monitor the status of calibration internally to get the updated scale factor for calculation of time period. Hence Hardware Interrupt block cannot use high resolution interrupt.

Calibration process provides scale factor which is used to calculate high resolution capture values in seconds.

Dependencies

To enable this parameter, select Enable high resolution capture parameter. This parameter is available only for specific TI processors.

Specify the calibration period in seconds.

Dependencies

To enable this parameter, select Enable high resolution capture parameter and Enable continuous calibration mode. This parameter is available only for specific TI processors.

The Continuous option performs continuous timestamp captures (events 1 through 4) using a circular buffer.

The One-Shot option enables the Enable One-Shot rearming control via input port option.

When this parameter is selected, a One-Shot capture sequence is re-armed as follows:

Dependencies

This parameter appears only when you select One-Shot for Select mode control.

The number of capture events after which you want to stop the capture sequence.

The eCAP process resets the counter after receiving a capture event timestamp. In this case, # represents the number of the capture event set in the Stop value after parameter.

The option that starts a capture event. In this case, # represents the number of the capture event set in the Stop value after parameter.

Select the output type for eCAP.

The output type is int the form of HRCLK cycles when used in HRCAP mode (high resolution mode) and SYSCLK when used in normal mode. When you set the output type to HRCLK/SYSCLK cycles in HRCAP mode (high resolution mode), it enables the port Scale factor.

The data type of the timestamp counter.

Outputs the capture event status flag at the output port CF. The block outputs 0 until the event is captured. After the event, the flag value is 1.

The data type of the output port CF.

Dependencies

This parameter appears only when you select Enable capture event status flag output.

Outputs the status of the elements of the FIFO buffer at the output port OF.

The data type of the output port OF.

Dependencies

This parameter appears only when you select Enable overflow status flag output.

Clock cycles uses the high-speed peripheral clock cycles of the processor.

Select Specify via dialog to enter the value in Waveform period, or select Input port to use a value from the T input port.

Period of the PWM waveform measured in clock cycles or seconds, as specified in Waveform period units.

Dependencies

This parameter appears only when Waveform period source is set to Specify via dialog.

The units used for measuring the duty cycle.

Select Specify via dialog to enter the value in Duty cycle, or select Input port to use a value from the W input port.

The ratio of PWM waveform pulse duration to PWM waveform period. This ratio is expressed in Duty cycle units.

When you select Active High, the compare value (duty cycle) defines the high time. Selecting Active Low directs the compare value to define the low time.

You can use the C28x Hardware Interrupt block to respond to this interrupt. In this case, # represents the number of the capture event set in the Stop value after parameter.

Dependencies

This parameter appears only when you set Operating mode to eCAP in the General tab.

Triggers an interrupt when the counter overflows.

Dependencies

This parameter appears only when you set Operating mode to eCAP in the General tab.

Posts interrupt when the value of counter is same as the value of the period register (CTR = PRD).

Dependencies

This parameter appears only when you set Operating mode to APWM in the General tab.

Posts interrupt when the value of the counter is same as the value of the compare register (CTR = CMP).

Dependencies

This parameter appears only when you set Operating mode to APWM in the General tab.