Each Generator (GCLK_GEN) can be set to run from one of eight different clock sources except GCLK_GEN[1], which can be set to run from one of seven sources. GCLK_GEN[1] is the only Generator that can be selected as source to others Generators.
Each generator GCLK_GEN[x] can be connected to one specific pin GCLK_IO[x]. A pin GCLK_IO[x] can be set either to act as source to GCLK_GEN[x] or to output the clock signal generated by GCLK_GEN[x].
The selected source can be divided. Each Generator can be enabled or disabled independently.
Each GCLK_GEN clock signal can then be used as clock source for Peripheral Channels. Each Generator output is allocated to one or several Peripherals.