22.2.1 Block Diagram

The figure below shows a detailed block diagram of the timer/counter.

Figure 22-2. Timer/Counter Block Diagram

The Counter (TCAn.CNT) register, Period and Compare (TCAn.PER and TCAn.CMPn) registers, and their corresponding buffer registers (TCAn.PERBUF and TCAn.CMPnBUF) are 16-bit registers. All buffer registers have a Buffer Valid (BV) flag indicating when the buffer contains a new value.

During ordinary operation, the counter value is continuously compared to zero and the period (PER) value to determine whether the counter has reached TOP or BOTTOM. The counter value can also be compared to the TCAn.CMPn registers.

The timer/counter can generate interrupt requests, events, or change the waveform output after being triggered by the Counter (TCAn.CNT) register reaching TOP, BOTTOM, or CMPn. After the triggering, the interrupt requests, events, or waveform output changes will occur on the next CLK_TCA cycle.

CLK_TCA is either the prescaled peripheral clock or events from the Event System, as shown in the figure below.

Figure 22-3. Timer/Counter Clock Logic