ESP32-mqtt笔记

基于ESP-IDF4.1

#include <stdio.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include "esp_wifi.h"
#include "esp_system.h"
#include "nvs_flash.h"
#include "esp_event.h"
#include "esp_netif.h"
#include "protocol_examples_common.h"

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#include "freertos/queue.h"

#include "lwip/sockets.h"
#include "lwip/dns.h"
#include "lwip/netdb.h"

#include "esp_log.h"
#include "mqtt_client.h"

static const char *TAG = "MQTT_EXAMPLE";

static esp_err_t mqtt_event_handler_cb(esp_mqtt_event_handle_t event)
{
    esp_mqtt_client_handle_t client = event->client;
    int msg_id;
    // your_context_t *context = event->context;
    switch (event->event_id) {
        case MQTT_EVENT_CONNECTED:
            ESP_LOGI(TAG, "MQTT_EVENT_CONNECTED");
            msg_id = esp_mqtt_client_publish(client, "/topic/qos1", "data_3", 0, 1, 0);
            ESP_LOGI(TAG, "sent publish successful, msg_id=%d", msg_id);

            msg_id = esp_mqtt_client_subscribe(client, "/topic/qos0", 0);
            ESP_LOGI(TAG, "sent subscribe successful, msg_id=%d", msg_id);

            msg_id = esp_mqtt_client_subscribe(client, "/topic/qos1", 1);
            ESP_LOGI(TAG, "sent subscribe successful, msg_id=%d", msg_id);

            msg_id = esp_mqtt_client_unsubscribe(client, "/topic/qos1");
            ESP_LOGI(TAG, "sent unsubscribe successful, msg_id=%d", msg_id);
            break;
        case MQTT_EVENT_DISCONNECTED:
            ESP_LOGI(TAG, "MQTT_EVENT_DISCONNECTED");
            break;

        case MQTT_EVENT_SUBSCRIBED:
            ESP_LOGI(TAG, "MQTT_EVENT_SUBSCRIBED, msg_id=%d", event->msg_id);
            msg_id = esp_mqtt_client_publish(client, "/topic/qos0", "data", 0, 0, 0);
            ESP_LOGI(TAG, "sent publish successful, msg_id=%d", msg_id);
            break;
        case MQTT_EVENT_UNSUBSCRIBED:
            ESP_LOGI(TAG, "MQTT_EVENT_UNSUBSCRIBED, msg_id=%d", event->msg_id);
            break;
        case MQTT_EVENT_PUBLISHED:
            ESP_LOGI(TAG, "MQTT_EVENT_PUBLISHED, msg_id=%d", event->msg_id);
            break;
        case MQTT_EVENT_DATA:
            ESP_LOGI(TAG, "MQTT_EVENT_DATA");
            printf("TOPIC=%.*s\r\n", event->topic_len, event->topic);
            printf("DATA=%.*s\r\n", event->data_len, event->data);
            break;
        case MQTT_EVENT_ERROR:
            ESP_LOGI(TAG, "MQTT_EVENT_ERROR");
            break;
        default:
            ESP_LOGI(TAG, "Other event id:%d", event->event_id);
            break;
    }
    return ESP_OK;
}

//mqtt时间处理程序
static void mqtt_event_handler(void *handler_args, esp_event_base_t base, int32_t event_id, void *event_data) {
    ESP_LOGD(TAG, "Event dispatched from event loop base=%s, event_id=%d", base, event_id);
    mqtt_event_handler_cb(event_data);
}

//启动mqtt
static void mqtt_app_start(void)
{
    esp_mqtt_client_config_t mqtt_cfg = {.uri = CONFIG_BROKER_URL,};

#if CONFIG_BROKER_URL_FROM_STDIN
    char line[128];

    if (strcmp(mqtt_cfg.uri, "FROM_STDIN") == 0) {
        int count = 0;
        printf("Please enter url of mqtt broker\n");
        while (count < 128) {
            //从stdin获取下一个字符
            int c = fgetc(stdin);
            if (c == '\n') {
                line[count] = '\0';
                break;
            } else if (c > 0 && c < 127) {
                line[count] = c;
                ++count;
            }
            vTaskDelay(10 / portTICK_PERIOD_MS);
        }
        mqtt_cfg.uri = line;
        printf("Broker url: %s\n", line);
    } else {
        ESP_LOGE(TAG, "Configuration mismatch: wrong broker url");
        abort();
    }
#endif

    esp_mqtt_client_handle_t client = esp_mqtt_client_init(&mqtt_cfg);
    esp_mqtt_client_register_event(client, ESP_EVENT_ANY_ID, mqtt_event_handler, client);
    esp_mqtt_client_start(client);
}

//入口
void app_main(void)
{
    ESP_LOGI(TAG, "[APP] Startup..");
    ESP_LOGI(TAG, "[APP] Free memory: %d bytes", esp_get_free_heap_size());
    ESP_LOGI(TAG, "[APP] IDF version: %s", esp_get_idf_version());

    esp_log_level_set("*", ESP_LOG_INFO);
    esp_log_level_set("MQTT_CLIENT", ESP_LOG_VERBOSE);
    esp_log_level_set("MQTT_EXAMPLE", ESP_LOG_VERBOSE);
    esp_log_level_set("TRANSPORT_TCP", ESP_LOG_VERBOSE);
    esp_log_level_set("TRANSPORT_SSL", ESP_LOG_VERBOSE);
    esp_log_level_set("TRANSPORT", ESP_LOG_VERBOSE);
    esp_log_level_set("OUTBOX", ESP_LOG_VERBOSE);

    ESP_ERROR_CHECK(nvs_flash_init());
    ESP_ERROR_CHECK(esp_netif_init());
    ESP_ERROR_CHECK(esp_event_loop_create_default());

    //连接网络
    ESP_ERROR_CHECK(example_connect());

    mqtt_app_start();
}

原文：https://gitee.com/EspressifSystems/esp-idf/tree/master/examples/protocols/mqtt/tcp