24.3.4 Events

The TCB can generate the events described in the following table:
Table 24-3. Event Generators in TCB
Generator Name Description Event Type Generating Clock Domain Length of Event
Peripheral Event
TCBn CAPT CAPT flag set Pulse CLK_PER One CLK_PER period
OVF OVF flag set

The conditions for generating the CAPT and OVF events are identical to those that will raise the corresponding interrupt flags in the Timer/Counter Interrupt Flags (TCBn.INTFLAGS) register. Refer to the EVSYS - Event System section for more details regarding event users and Event System configuration.

The TCB can receive the events described in the following table:
Table 24-4. Event Users and Available Event Actions in TCB
User Name Description Input Detection Async/Sync
Peripheral Input
TCBn CAPT Time-Out Check Count mode Edge Sync
Input Capture on Event Count mode
Input Capture Frequency Measurement Count mode
Input Capture Pulse-Width Measurement Count mode
Input Capture Frequency and Pulse-Width Measurement Count mode
Single-Shot Count mode Both
COUNT Event as clock source in combination with a count mode Sync

CAPT and COUNT are TCB event users that detect and act upon input events.

The COUNT event user is enabled on the peripheral by modifying the Clock Select (CLKSEL) bit field in the Control A (TCBn.CTRLA) register to EVENT and setting up the Event System accordingly.

If the Capture Event Input Enable (CAPTEI) bit in the Event Control (TCBn.EVCTRL) register is written to ‘1’, incoming events will result in an event action as defined by the Event Edge (EDGE) bit in Event Control (TCBn.EVCTRL) register, and the Timer Mode (CNTMODE) bit field in Control B (TCBn.CTRLB) register. The event must last for at least one CLK_PER cycle to be recognized.

If the Asynchronous mode is enabled for Single-Shot mode, the event is edge-triggered and will capture changes on the event input shorter than one peripheral clock cycle.