A microcontroller (2) has a processor (6), peripherals (18, 20, 22, 24, 26), a programmable peripheral interconnect (PPI) (10), an event-generating unit (EGU) (17), and a memory (8). The peripherals respond to task signals from the PPI. The EGU responds to a predetermined change to the contents of an event-generating register (57, 59) by signalling an event to the PPI. Stored PPI mappings can map an EGU event to a task of one of the peripherals. Mappings from one EGU event to two or more peripheral tasks cause the PPI to respond to an event signal from the EGU by sending the respective task signals within a maximum time limit. Software in the memory comprises instructions to store such mappings in a mapping memory, and to make the predetermined change to the contents of the event-generating register. In another aspect, an interrupt-generating unit (17) is arranged to send an interrupt to the processor (6) in response to receiving a task signal from the PPI (10).