The capture units allow time-based logging of external logic level signal transitions on the capture input pins.
Devices in the F2833x family have four independent capture units; one of them is shown in Slide 7-56 above. Each capture unit is associated with a capture input pin. An event prescaler can be initialized to reduce the input frequency. Four polarity select bit fields define rising or falling edges as the trigger events for capture events 1 to 4. The measurement time-base is derived from the frequency SYSCLKOUT, in the case of the F28335ControlCard, this is 100 MHz. This signal will increment a 32-bit Time-Stamp Counter. In the event of a capture trigger signal the current value of this counter is captured and stored in the corresponding capture register.
Multiple identical eCAP modules can be contained in a 2833x system as shown in Slide 7-56. The number of modules is device-dependent and is based on target application needs.