28.5.1 Timer Clock Source

The two clock sources for the 64-bit timer are the peripheral clock and the generic clock (GCLK), which can be fully asynchronous to the peripheral clock. The selected clock can be prescaled before triggering the 64-bit timer.

The GCLK is selected as source clock for the prescaler when the SGCLK bit, in the Mode register (PIT64B_MR), is written to 1. The prescaler is active as soon as PIT64B_MR.PRESCALER>0.

If PIT64B_MR.PRESCALER=0, the timer is triggered either on each rising edge detection event of the GCLK if PIT64B_MR.SGCLK is written to 1, or on each rising edge of the peripheral clock.

If GCLK is selected, the frequency must be at least 3 times lower than the peripheral clock.