The interrupt controller

Real-time systems have improved their accuracy thanks to the rapid evolution of modern embedded systems, in particular from the research on interrupt controllers. Assigning different priorities to interrupt lines guarantees a lower interrupt latency for higher-priority interrupt sources and makes the system react faster to prioritized events. Interrupts may, however, occur at any time while the system is running, including during the execution of another interrupt service routine. In this case, the interrupt controller provides a way to chain the interrupt handlers, and the order of execution depends on the priority levels assigned to the interrupt source.

One of the reasons for the popularity of the Cortex-M family of microprocessors among real-time and low-power embedded applications is perhaps the design of its programmable real-time controller—namely, the Nested Vector Interrupt Controller, or NVIC for short. The NVIC supports up to 240 interrupt...