07 - 网络通信

WiFi 与蓝牙连接配置

WiFi 连接

Station 模式 (连接路由器)

#include "esp_wifi.h"
#include "esp_event.h"
 
#define WIFI_SSID     "YourSSID"
#define WIFI_PASSWORD "YourPassword"
 
static void wifi_event_handler(void *event_handler_arg, esp_event_base_t event_base,
                                int32_t event_id, void *event_data)
{
    if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
        esp_wifi_connect();
    }
    else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_CONNECTED) {
        printf("WiFi connected\n");
    }
    else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
        ip_event_got_ip_t *event = (ip_event_got_ip_t *)event_data;
        printf("Got IP: " IPSTR "\n", IP2STR(&event->ip_info.ip));
    }
    else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
        printf("WiFi disconnected, reconnecting...\n");
        esp_wifi_connect();
    }
}
 
void wifi_init_sta(void)
{
    esp_netif_init();
    esp_event_loop_create_default();
    esp_netif_create_default_wifi_sta();
 
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    esp_wifi_init(&cfg);
 
    esp_event_handler_register(WIFI_EVENT, ESP_EVENT_ANY_ID, wifi_event_handler, NULL);
    esp_event_handler_register(IP_EVENT, IP_EVENT_STA_GOT_IP, wifi_event_handler, NULL);
 
    wifi_config_t wifi_config = {
        .sta = {
            .threshold.authmode = WIFI_AUTH_WPA2_PSK,
        },
    };
    memcpy(wifi_config.sta.ssid, WIFI_SSID, strlen(WIFI_SSID));
    memcpy(wifi_config.sta.password, WIFI_PASSWORD, strlen(WIFI_PASSWORD));
 
    esp_wifi_set_mode(WIFI_MODE_STA);
    esp_wifi_set_config(WIFI_IF_STA, &wifi_config);
    esp_wifi_start();
 
    printf("WiFi started, connecting to %s...\n", WIFI_SSID);
}

SoftAP 模式 (建立热点)

void wifi_init_ap(void)
{
    esp_netif_init();
    esp_event_loop_create_default();
    esp_netif_create_default_wifi_softap();
 
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    esp_wifi_init(&cfg);
 
    wifi_config_t ap_config = {
        .ap = {
            .ssid = "ESP32_Config",
            .ssid_len = strlen("ESP32_Config"),
            .password = "12345678",
            .max_connection = 4,
            .authmode = WIFI_AUTH_WPA_WPA2_PSK
        }
    };
 
    esp_wifi_set_mode(WIFI_MODE_AP);
    esp_wifi_set_config(WIFI_IF_AP, &ap_config);
    esp_wifi_start();
 
    printf("AP started, SSID: ESP32_Config\n");
}

WiFi 扫描

void wifi_scan(void)
{
    wifi_scan_config_t scan_config = {
        .show_hidden = true,
        .scan_type = WIFI_SCAN_TYPE_ACTIVE,
        .scan_time.active.min = 100,
        .scan_time.active.max = 500
    };
 
    esp_wifi_scan_start(&scan_config, true);
 
    uint16_t ap_num = 20;
    wifi_ap_record_t ap_info[20];
    esp_wifi_scan_get_ap_records(&ap_num, ap_info);
 
    printf("Found %d networks:\n", ap_num);
    for (int i = 0; i < ap_num; i++) {
        printf("  %s  RSSI: %d\n", ap_info[i].ssid, ap_info[i].rssi);
    }
}

HTTP 客户端

GET 请求

#include "esp_http_client.h"
 
esp_err_t http_event_handler(esp_http_client_event_t *evt)
{
    switch (evt->event_id) {
        case HTTP_EVENT_ON_DATA:
            printf("%.*s\n", evt->data_len, (char *)evt->data);
            break;
        case HTTP_EVENT_ON_FINISH:
            printf("HTTP request finished\n");
            break;
        default:
            break;
    }
    return ESP_OK;
}
 
void http_get_request(void)
{
    esp_http_client_config_t config = {
        .url = "http://httpbin.org/get",
        .event_handler = http_event_handler
    };
 
    esp_http_client_handle_t client = esp_http_client_init(&config);
    esp_http_client_perform(client);
    esp_http_client_cleanup(client);
}

POST 请求

void http_post_request(void)
{
    const char *post_data = "{\"key\":\"value\"}";
 
    esp_http_client_config_t config = {
        .url = "http://httpbin.org/post",
        .method = HTTP_METHOD_POST,
        .event_handler = http_event_handler
    };
 
    esp_http_client_handle_t client = esp_http_client_init(&config);
    esp_http_client_set_header(client, "Content-Type", "application/json");
    esp_http_client_set_post_field(client, post_data, strlen(post_data));
 
    esp_http_client_perform(client);
    esp_http_client_cleanup(client);
}

MQTT

订阅与发布

#include "mqtt_client.h"
 
static esp_mqtt_client_handle_t mqtt_client;
 
static void mqtt_event_handler(void *handler_args, esp_event_base_t base,
                                int32_t event_id, void *event_data)
{
    esp_mqtt_event_handle_t event = (esp_mqtt_event_handle_t)event_data;
 
    switch (event->event_id) {
        case MQTT_EVENT_CONNECTED:
            printf("MQTT connected\n");
            esp_mqtt_client_subscribe(mqtt_client, "/topic/sub", 0);
            break;
        case MQTT_EVENT_DATA:
            printf("Topic: %.*s\n", event->topic_len, event->topic);
            printf("Data: %.*s\n", event->data_len, event->data);
            break;
        case MQTT_EVENT_DISCONNECTED:
            printf("MQTT disconnected\n");
            break;
    }
}
 
void mqtt_app_start(void)
{
    esp_mqtt_client_config_t mqtt_cfg = {
        .broker.address.uri = "mqtt://broker.emqx.io:1883",
        .credentials.client_id = "esp32_client"
    };
 
    mqtt_client = esp_mqtt_client_init(&mqtt_cfg);
    esp_mqtt_client_register_event(mqtt_client, ESP_EVENT_ANY_ID, mqtt_event_handler, NULL);
    esp_mqtt_client_start(mqtt_client);
}
 
void mqtt_publish(const char *topic, const char *data)
{
    esp_mqtt_client_publish(mqtt_client, topic, data, 0, 1, 0);
}

常用 MQTT Broker

Broker	地址	端口
EMQX	broker.emqx.io	1883
Mosquitto	test.mosquitto.org	1883
HiveMQ	broker.hivemq.com	1883

蓝牙低功耗 (BLE)

GATT 服务器

#include "esp_bt.h"
#include "esp_gatt_common_api.h"
#include "esp_gap_ble_api.h"
#include "esp_gatts_api.h"
 
#define GATTS_SERVICE_UUID    0x00FF
#define GATTS_CHAR_UUID       0xFF01
 
static const uint8_t manufacturer[3] = {'E', 'S', 'P'};
 
static void gatts_profile_event_handler(esp_gatts_cb_event_t event,
                                         esp_gatt_if_t gatts_if,
                                         esp_ble_gatts_cb_param_t *param)
{
    switch (event) {
        case ESP_GATTS_REG_EVT:
            printf("GATT server registered\n");
            break;
        case ESP_GATTS_CREATE_ATTR_TABLE:
            printf("Attribute table created\n");
            break;
        case ESP_GATTS_READ_EVT: {
            printf("Read request, handle: %d\n", param->read.handle);
            esp_gatt_rsp_t rsp = {
                .attr_value.len = 3,
                .attr_value.value = {manufacturer[0], manufacturer[1], manufacturer[2]}
            };
            esp_ble_gatts_send_response(gatts_if, param->read.conn_id,
                                        param->read.trans_id, ESP_GATT_OK, &rsp);
            break;
        }
    }
}
 
void ble_gatts_init(void)
{
    esp_bluedroid_init();
    esp_bluedroid_enable();
    esp_ble_gatts_register_callback(gatts_profile_event_handler);
    esp_ble_gatts_app_register(0);
}

BLE 扫描

static void ble_scan_result(esp_ble_gap_cb_param_t *param)
{
    if (param->scan_rst.ble_adv && param->scan_rst.adv_name_len > 0) {
        printf("Found device: %.*s\n",
               param->scan_rst.adv_name_len,
               param->scan_rst.ble_adv->name);
    }
}
 
void ble_scan_start(void)
{
    esp_ble_gap_register_callback(ble_scan_result);
    esp_ble_gap_start_scanning(30);  // 扫描30秒
}

网络时间同步 (NTP)

#include "esp_sntp.h"
 
void sntp_init_time(void)
{
    esp_sntp_setoperatingmode(SNTP_OPMODE_POLL);
    esp_sntp_setservername(0, "pool.ntp.org");
    esp_sntp_setservername(1, "time.google.com");
 
    sntp_set_time_sync_notification_cb([](struct timeval *tv) {
        printf("Time synchronized!\n");
    });
 
    esp_sntp_init();
}
 
// 获取当前时间
void get_current_time(void)
{
    time_t now;
    struct tm timeinfo;
    time(&now);
    localtime_r(&now, &timeinfo);
 
    printf("Current time: %04d-%02d-%02d %02d:%02d:%02d\n",
           timeinfo.tm_year + 1900, timeinfo.tm_mon + 1, timeinfo.tm_mday,
           timeinfo.tm_hour, timeinfo.tm_min, timeinfo.tm_sec);
}

参考资料

官方文档

ESP-IDF WiFi API - WiFi Station/SoftAP 模式
ESP-IDF HTTP 客户端 - HTTP GET/POST 请求
ESP-IDF MQTT 客户端 - MQTT 订阅与发布
ESP-IDF BLE API - 蓝牙低功耗开发
ESP-IDF NimBLE - NimBLE 主机协议栈

技术参考

ESP-IDF WiFi 示例 - WiFi 官方示例
ESP-IDF MQTT 示例 - MQTT 官方示例
MQTT 协议规范 - MQTT 3.1.1/5.0 协议规范
BLE GATT 服务 - GATT 服务规范

图片参考

ESP32 WiFi 网络架构

下一步

学习 08_传感器集成连接实际传感器
学习 09_云平台接入连接云端服务
学习 10_低功耗设计优化功耗

Obsidian AI管理笔记

目录

07_网络通信

07 - 网络通信

WiFi 连接

Station 模式 (连接路由器)

SoftAP 模式 (建立热点)

WiFi 扫描

HTTP 客户端

GET 请求

POST 请求

MQTT

订阅与发布

常用 MQTT Broker

蓝牙低功耗 (BLE)

GATT 服务器

BLE 扫描

网络时间同步 (NTP)

参考资料

官方文档

技术参考

图片参考

相关链接

反向链接

进阶学习

下一步

关系图谱

目录

反向链接