19.5.3 Clocks
The EIC bus clock (CLK_EIC_APB) can be enabled and disabled in the Power Manager, and the default state of CLK_EIC_APB can be found in the Peripheral Clock Masking section in PM – Power Manager.
A generic clock (GCLK_EIC) is required to clock the peripheral. This clock must be configured and enabled in the Generic Clock Controller before using the peripheral. Refer to GCLK – Generic Clock Controller.
This generic clock is asynchronous to the user interface clock (CLK_EIC_APB). Due to this asynchronicity, writes to certain registers will require synchronization between the clock domains. Refer to Synchronization for further details.