Interface for external interrupt controller.
The External Interrupt Controller (EIC) allows pins to be configured as external interrupts. Each external interrupt has its own interrupt request and can be individually masked. Each external interrupt can generate an interrupt on rising or falling edge, or high or low level. Every interrupt pin can also be configured to be asynchronous, in order to wake-up the part from sleep modes where the CLK_SYNC clock has been disabled.
A basic use case: A user button is configured for falling edge trigger and async mode.