What is an external interrupt and the triggering mode of the external interrupt?

2020-08-17 14:39:04 Zongheng Intelligente Steuerung 5

What is an external interrupt? Where is the data sheet?

(1) One of the interrupt types supported by SoC is called external interrupt. Internal interrupts refer to interrupt sources coming from inside the SoC (usually internal peripherals), such as interrupts generated by serial ports, timers and other components; external interrupts are interrupts generated by devices external to the SoC through the GPI0 pin corresponding to the external interrupt.
(2) The buttons are implemented in the SoC using external interrupts. The specific implementation method is: connect the button circuit to the GPIO of the external interrupt, and then configure GPI0 to the external interrupt mode. At this time, people change the voltage of the key circuit by pressing the button. This voltage will trigger the external interrupt corresponding to GPI0 and pass it through the pin to the CPU for processing.

External interrupt trigger mode

Level triggering and edge triggering
(1) There are two main trigger modes for external interrupts: level trigger and edge trigger.
(2) Level triggering means that as long as the level on GPIO meets the conditions, interrupts will be triggered continuously. Level triggering is divided into high level triggering and low level triggering. The characteristic of level triggering is that as long as the level meets the conditions, the interrupt will be triggered continuously.
(3) Edge triggering is divided into three types: rising edge triggering, falling edge triggering and double edge triggering. Edge triggering does not care about the normal state of the level, but only cares about the moment when the level changes (edge ​​triggering does not care about whether the level itself is high or low, but only cares about whether the change is from high to low or from low to high).
Analyze the work of the keys: If we are concerned about the two events of key press and pop-up, then edge triggering should be used to process the keys; if we are concerned about the period of time when the key is pressed/pop-up, then It should be level triggered.

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