Events are used to notify peripherals and the CPU about events that have happened, for example a state change in a peripheral. A peripheral may generate multiple events, where each event has a separate register in that peripheral's event register group.
An event is generated when the peripheral itself toggles the corresponding event signal, and the event register is updated to reflect that the event has been generated, see figure Peripheral interface. An event register is cleared when a 0 is written to it by firmware. Events can be generated by the peripheral even when the event register is set to 1.