Datasheet

• COUNT8: The 8-bit TC has its own Period register (PER). This register is used to store the period

value that can be used as the top value for waveform generation.

• COUNT16: 16-bit is the default counter mode. There is no dedicated period register in this mode.

• COUNT32: This mode is achieved by pairing two 16-bit TC peripherals. TC3 is paired with TC4,

and TC5 is paired with TC6. TC7 does not support 32-bit resolution.

When paired, the TC peripherals are configured using the registers of the even-numbered TC (TC4 or

TC6 respectively). The odd-numbered partner (TC3 or TC5 respectively) will act as slave, and the Slave

bit in the Status register (STATUS.SLAVE) will be set. The register values of a slave will not reflect the

registers of the 32-bit counter. Writing to any of the slave registers will not affect the 32-bit counter.

Normal access to the slave COUNT and CCx registers is not allowed.

30.6.2.5 Counter Operations

The counter can be set to count up or down. When the counter is counting up and the top value is

reached, the counter will wrap around to zero on the next clock cycle. When counting down, the counter

will wrap around to the top value when zero is reached. In one-shot mode, the counter will stop counting

after a wraparound occurs.

The counting direction is set by the Direction bit in the Control B register (CTRLB.DIR). If this bit is zero

the counter is counting up, and counting down if CTRLB.DIR=1. The counter will count up or down for

each tick (clock or event) until it reaches TOP or ZERO. When it is counting up and TOP is reached, the

counter will be set to zero at the next tick (overflow) and the Overflow Interrupt Flag in the Interrupt Flag

Status and Clear register (INTFLAG.OVF) will be set. It is also possible to generate an event on overflow

or underflow when the Overflow/Underflow Event Output Enable bit in the Event Control register

(EVCTRL.OVFEO) is one.

It is possible to change the counter value (by writing directly in the COUNT register) even when the

counter is running. When starting the TC, the COUNT value will be either ZERO or TOP (depending on

the counting direction set by CTRLBSET.DIR or CTRLBCLR.DIR), unless a different value has been

written to it, or the TC has been stopped at a value other than ZERO. The write access has higher priority

than count, clear, or reload. The direction of the counter can also be changed during normal operation.