22.4.2.2 Prescaler Selection

The GCLK_TCn is fed into the internal prescaler.

The prescaler consists of a counter that counts up to the selected prescaler value; when this value is reached, the output of the prescaler toggles.

If the prescaler value is higher than one, the counter update condition can optionally be executed on either the next GCLK_TCn clock pulse or the next prescaled clock pulse. For further details, refer to Prescaler (CTRLA.PRESCALER) and Counter Synchronization (CTRLA.PRESYNC) description.

Prescaler outputs from GCLK_TC/1 to GCLK_TC/1024 are available. For a complete list of available prescaler outputs, see the register description for the Prescaler bit field in the Control A register (CTRLA.PRESCALER).

Note: When counting events, the prescaler is bypassed.

The combined stream of prescaler ticks and event action ticks is referred to as CLK_TC_CNT.