esp32之GPIO中断

无论接触哪一款芯片或者模组，理解GPIO是一个嵌入式工程师最基本的修为

源码路径：esp-idf/examples/peripherals/gpio

源码使用：

This test code shows how to configure gpio and how to use gpio interrupt.

## GPIO functions:

* GPIO18: output
* GPIO19: output
* GPIO4: input, pulled up, interrupt from rising edge and falling edge
* GPIO5: input, pulled up, interrupt from rising edge.

## Test:
* Connect GPIO18 with GPIO4
* Connect GPIO19 with GPIO5
* Generate pulses on GPIO18/19, that triggers interrupt on GPIO4/5

/* GPIO Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "driver/gpio.h"

/**
 * Brief:
 * This test code shows how to configure gpio and how to use gpio interrupt.
 *
 * GPIO status:
 * GPIO18: output
 * GPIO19: output
 * GPIO4:  input, pulled up, interrupt from rising edge and falling edge
 * GPIO5:  input, pulled up, interrupt from rising edge.
 *
 * Test:
 * Connect GPIO18 with GPIO4
 * Connect GPIO19 with GPIO5
 * Generate pulses on GPIO18/19, that triggers interrupt on GPIO4/5
 *
 */

#define GPIO_OUTPUT_IO_0    18
#define GPIO_OUTPUT_IO_1    19
#define GPIO_OUTPUT_PIN_SEL  ((1ULL<<GPIO_OUTPUT_IO_0) | (1ULL<<GPIO_OUTPUT_IO_1))
#define GPIO_INPUT_IO_0     4
#define GPIO_INPUT_IO_1     5
#define GPIO_INPUT_PIN_SEL  ((1ULL<<GPIO_INPUT_IO_0) | (1ULL<<GPIO_INPUT_IO_1))
#define ESP_INTR_FLAG_DEFAULT 0

static xQueueHandle gpio_evt_queue = NULL;

static void IRAM_ATTR gpio_isr_handler(void* arg)
{
    uint32_t gpio_num = (uint32_t) arg;
    xQueueSendFromISR(gpio_evt_queue, &gpio_num, NULL);
}

static void gpio_task_example(void* arg)
{
    uint32_t io_num;
    for(;;) {
        if(xQueueReceive(gpio_evt_queue, &io_num, portMAX_DELAY)) {
            printf("GPIO[%d] intr, val: %d\n", io_num, gpio_get_level(io_num));
        }
    }
}

void app_main()
{
    gpio_config_t io_conf;
    //disable interrupt
    io_conf.intr_type = GPIO_PIN_INTR_DISABLE;
    //set as output mode
    io_conf.mode = GPIO_MODE_OUTPUT;
    //bit mask of the pins that you want to set,e.g.GPIO18/19
    io_conf.pin_bit_mask = GPIO_OUTPUT_PIN_SEL;
    //disable pull-down mode
    io_conf.pull_down_en = 0;
    //disable pull-up mode
    io_conf.pull_up_en = 0;
    //configure GPIO with the given settings
    gpio_config(&io_conf);

    //interrupt of rising edge
    io_conf.intr_type = GPIO_PIN_INTR_POSEDGE;
    //bit mask of the pins, use GPIO4/5 here
    io_conf.pin_bit_mask = GPIO_INPUT_PIN_SEL;
    //set as input mode    
    io_conf.mode = GPIO_MODE_INPUT;
    //enable pull-up mode
    io_conf.pull_up_en = 1;
    gpio_config(&io_conf);

    //change gpio intrrupt type for one pin
    gpio_set_intr_type(GPIO_INPUT_IO_0, GPIO_INTR_ANYEDGE);

    //create a queue to handle gpio event from isr
    gpio_evt_queue = xQueueCreate(10, sizeof(uint32_t));
    //start gpio task
    xTaskCreate(gpio_task_example, "gpio_task_example", 2048, NULL, 10, NULL);

    //install gpio isr service
    gpio_install_isr_service(ESP_INTR_FLAG_DEFAULT);
    //hook isr handler for specific gpio pin
    gpio_isr_handler_add(GPIO_INPUT_IO_0, gpio_isr_handler, (void*) GPIO_INPUT_IO_0);
    //hook isr handler for specific gpio pin
    gpio_isr_handler_add(GPIO_INPUT_IO_1, gpio_isr_handler, (void*) GPIO_INPUT_IO_1);

    //remove isr handler for gpio number.
    gpio_isr_handler_remove(GPIO_INPUT_IO_0);
    //hook isr handler for specific gpio pin again
    gpio_isr_handler_add(GPIO_INPUT_IO_0, gpio_isr_handler, (void*) GPIO_INPUT_IO_0);

    int cnt = 0;
    while(1) {
        printf("cnt: %d\n", cnt++);
        vTaskDelay(1000 / portTICK_RATE_MS);
        gpio_set_level(GPIO_OUTPUT_IO_0, cnt % 2);
        gpio_set_level(GPIO_OUTPUT_IO_1, cnt % 2);
    }
}

代码很简单，接下来分析一下如何注册一个gpio中断：

1.创建一个gpio_config_t结构体，配置gpio_config_t结构体变量

2.使能gpio_config_t结构体gpio_config(&io_conf)

3.使用gpio_install_isr_service(ESP_INTR_FLAG_DEFAULT)允许每个GPIO注册中断处理程序

4.注册中断gpio_isr_handler_add(GPIO_INPUT_IO_0, gpio_isr_handler, (void*) GPIO_INPUT_IO_0)

以上就是esp32注册一个中断的步骤，注意不再使用中断时释放中断gpio_isr_handler_remove(GPIO_INPUT_IO_0)

同时说明一下，在FreeRTOS里面，一般不会在中断处理函数里面做太多东西，PS：RTOS嵌入式实时操作系统，一般的做法是间接通过一个等待队列来通知中断的发生，这样做的目的可大大减少中断处理函数花费的时间，达到实时目的。

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