ECUs do both cyclic and event-driven, but typically the software logic is event driven, the communication is cyclic. There's cyclic communication by sending me

ECUs do both cyclic and event-driven, but typically the software logic is event driven, the communication is cyclic. There's cyclic communication by sending messages over CAN (if reliability doesn't matter that much) or FlexRay (if reliability matters), so if you examine the network, you'll typically see the same PDUs repeat in a cyclic manner. But an individual ECU will handle the bulk of its logic in an event-driven way. An interrupt will trigger for the incoming CAN frame (and that's an event-driven thing!) but a couple of layers up it will most likely just set a flag for what changed, and it will actually be taken care on a logical level when the relevant task's loop runs next time.