STM32 external interrupt register configuration analysis

The difference between events and interrupts:

As can be seen from the figure above: the trigger sources of events and interrupts are the same, both can be (external trigger edge and software interrupt register trigger)

1> When a trigger edge arrives or the software triggers the interrupt to start, the trigger signal passes through the OR gate and enters the request suspend register to suspend, and on the other hand, enters the AND gate in the figure to trigger the event pulse. If the event mask register is configured to mask the event, the pulse generator will not be started to generate a pulse signal (but the suspend bit will still be set. This is purely my own understanding. According to the data manual, it will not be suspended here). After the No. 2 route is suspended, if the interrupt register allows it, an interrupt request will be sent to the NVIC, which triggers the core action.

2> The difference between interrupts and events is that the result of an event will directly lead to the generation of an output pulse, which will trigger the corresponding hardware action. This process is automatically completed without the participation of software. Interrupts, on the other hand, require a request to the processor and enter the interrupt service function to process data, which requires the participation of software and reduces the efficiency of the CPU.

The following is a method to configure an interrupt using registers

Before that we need to understand several registers:

EXTI_IMR, EXTI_EMR, EXTI_PR, EXTI_RTSR, EXTI_ETSR, EXTI_SWIER, EXTI_PR registers

External interrupt register AFIO_EXTI[0-4];

If time output is needed, we also need the AFIO_EVCR register

The above configuration is for the peripherals. After completion, we need to perform the same configuration on the kernel. This is the end.