MQTT 智能家居通信

MQTT 智能家居通信

概述

本节介绍智能家居面板的 MQTT 通信设计和实现。学习完成后，您将能够：

• 设计智能家居系统的 MQTT Topic 结构
• 实现面板状态和传感器数据的 MQTT 发布
• 处理 MQTT 远程控制指令并更新 UI
• 实现 WiFi 断线重连和状态同步

前置要求

在开始本节之前，请确保：

• 已掌握 MQTT 协议基础
• 已完成 LVGL 基础配置
• 已完成传感器数据采集配置
• Mosquitto/EMQX Broker 已运行

MQTT Topic Design

Smart Home Topic Tree

home/                              # 根主题
├── panel/{device_id}/             # 面板相关
│   ├── status                    # 面板状态
│   ├── sensors                   # 传感器数据
│   ├── screen                    # 屏幕控制
│   ├── command                   # 面板命令
│   └── display                   # 显示内容控制
├── sensor/{room}/                 # 传感器数据
│   ├── temperature               # 温度
│   ├── humidity                  # 湿度
│   ├── light                     # 光照
│   └── motion                    # 运动检测
├── light/{room}/                 # 灯光控制
│   ├── set                       # 设置灯光状态
│   ├── brightness                # 设置亮度
│   ├── color_temp                # 设置色温
│   └── status                    # 灯光状态报告
├── climate/{room}/               # 环境控制
│   ├── temperature_set           # 温度设定
│   ├── mode                      # 模式
│   └── status                    # 状态报告
├── scene/{room}/                 # 场景控制
│   └── trigger                   # 触发场景
├── alarm/{zone}/                 # 安防告警
│   └── sensor                    # 传感器告警
└── system/                       # 系统消息
    ├── status                    # 系统状态
    └── ota                       # OTA 更新通知

Topic Design Best Practices

原则	说明	示例
层级清晰	按功能/房间/设备分类	home/light/livingroom/set
命令分离	控制命令和状态上报分开	set 和 status 不同主题
房间隔离	每个房间有独立的主题层级	home/light/livingroom/ vs home/light/bedroom/
设备标识	使用 device_id 区分设备	home/panel/panel_01/status

MQTT Communication Implementation

Complete MQTT Integration

#include <WiFi.h>
#include <PubSubClient.h>

// MQTT 配置
const char* mqttServer = "192.168.1.100";
const int mqttPort = 1883;
const char* mqttUser = "node_red";
const char* mqttPassword = "node_red";
const char* deviceID = "panel_livingroom_01";

WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);

// Topic 定义
const char* topicStatus = "home/panel/livingroom_01/status";
const char* topicSensors = "home/panel/livingroom_01/sensors";
const char* topicScreen = "home/panel/livingroom_01/screen";
const char* topicCommand = "home/panel/livingroom_01/command";

// 订阅主题列表
const char* subscribeTopics[] = {
  "home/light/livingroom/status",
  "home/climate/livingroom/status",
  "home/scene/livingroom/trigger",
  topicScreen,
  topicCommand
};

// MQTT 回调处理
void mqttCallback(char* topic, byte* payload, unsigned int length) {
  String message;
  for (unsigned int i = 0; i < length; i++) {
    message += (char)payload[i];
  }

  Serial.printf("MQTT 接收: [%s] %s\n", topic, message.c_str());

  // 灯光状态更新
  if (strcmp(topic, "home/light/livingroom/status") == 0) {
    StaticJsonDocument<128> doc;
    deserializeJson(doc, message);

    bool lightOn = doc["state"] == "ON";
    int brightness = doc["brightness"] | 100;

    // 更新 LVGL UI
    update_light_ui(lightOn, brightness);
  }
  // 场景触发
  else if (strcmp(topic, "home/scene/livingroom/trigger") == 0) {
    update_scene_ui(message.c_str());
  }
  // 屏幕控制
  else if (strcmp(topic, topicScreen) == 0) {
    if (message == "sleep") {
      lv_disp_set_brightness(NULL, 0);  // 熄屏
    } else if (message == "wake") {
      lv_disp_set_brightness(NULL, 255);  // 点亮
    }
  }
  // 面板命令
  else if (strcmp(topic, topicCommand) == 0) {
    handle_panel_command(message.c_str());
  }
}

// 连接 MQTT Broker
void connectMQTT() {
  while (!mqttClient.connected()) {
    Serial.print("MQTT 连接中...");

    if (mqttClient.connect(deviceID, mqttUser, mqttPassword)) {
      Serial.println("已连接");

      // 订阅所有主题
      for (const char* subTopic : subscribeTopics) {
        mqttClient.subscribe(subTopic);
        Serial.printf("已订阅: %s\n", subTopic);
      }

      // 发布上线消息
      mqttClient.publish(topicStatus,
        "{\"state\":\"online\",\"device\":\"panel_livingroom_01\"}");
    } else {
      Serial.printf("连接失败 (rc=%d)，5秒后重试\n", mqttClient.state());
      delay(5000);
    }
  }
}

UI Update via MQTT

MQTT-Driven UI Updates

// 灯光 UI 更新
void update_light_ui(bool isOn, int brightness) {
  // 更新灯光图标
  lv_obj_t* lightIcon = lv_obj_get_child(lightCard, 0);
  if (isOn) {
    lv_label_set_text(lightIcon, "💡");
    lv_obj_set_style_bg_color(lightCard, lv_color_hex(0xFFD600), 0);
  } else {
    lv_label_set_text(lightIcon, "🔅");
    lv_obj_set_style_bg_color(lightCard, lv_color_hex(0x333333), 0);
  }

  // 更新亮度标签
  char buf[16];
  sprintf(buf, "亮度 %d%%", brightness);
  lv_obj_t* brightnessLabel = lv_obj_get_child(lightCard, 1);
  lv_label_set_text(brightnessLabel, buf);

  // 更新亮度滑块（但不触发值变化事件）
  lv_obj_t* slider = lv_obj_get_child(lightCard, 2);
  lv_slider_set_value(slider, brightness, LV_ANIM_ON);
}

// 场景 UI 更新
void update_scene_ui(const char* sceneName) {
  if (strcmp(sceneName, "离家") == 0) {
    lv_label_set_text(sceneIndicator, "🏃 离家模式");
    lv_obj_set_style_bg_color(sceneIndicator, lv_palette_main(LV_PALETTE_GREY), 0);
  } else if (strcmp(sceneName, "回家") == 0) {
    lv_label_set_text(sceneIndicator, "🏠 回家模式");
    lv_obj_set_style_bg_color(sceneIndicator, lv_palette_main(LV_PALETTE_GREEN), 0);
  } else if (strcmp(sceneName, "睡眠") == 0) {
    lv_label_set_text(sceneIndicator, "🌙 睡眠模式");
    lv_obj_set_style_bg_color(sceneIndicator, lv_palette_main(LV_PALETTE_INDIGO), 0);
  }
}

Touch Commands to MQTT

Button to MQTT

// 灯光按钮点击 → MQTT 命令
void light_btn_cb(lv_event_t* e) {
  static bool lightState = false;
  lightState = !lightState;

  // 构建 MQTT 消息
  StaticJsonDocument<64> doc;
  doc["state"] = lightState ? "ON" : "OFF";

  char buffer[64];
  serializeJson(doc, buffer);

  mqttClient.publish("home/light/livingroom/set", buffer);
}

// 亮度滑块 → MQTT 命令
void brightness_slider_cb(lv_event_t* e) {
  lv_obj_t* slider = lv_event_get_target(e);
  int value = lv_slider_get_value(slider);

  StaticJsonDocument<64> doc;
  doc["brightness"] = value;

  char buffer[64];
  serializeJson(doc, buffer);
  mqttClient.publish("home/light/livingroom/brightness/set", buffer);
}

Connection Monitoring

WiFi and MQTT Status Display

// 连接状态指示器
lv_obj_t* wifiIndicator;
lv_obj_t* mqttIndicator;

void create_connection_indicators() {
  // WiFi 状态文字
  wifiIndicator = lv_label_create(screen);
  lv_obj_align(wifiIndicator, LV_ALIGN_TOP_RIGHT, -10, 10);

  // MQTT 状态文字
  mqttIndicator = lv_label_create(screen);
  lv_obj_align(mqttIndicator, LV_ALIGN_TOP_RIGHT, -10, 30);
}

void update_connection_indicators() {
  // 更新 WiFi 状态
  if (WiFi.status() == WL_CONNECTED) {
    lv_label_set_text(wifiIndicator, "📶 WiFi 已连接");
    lv_obj_set_style_text_color(wifiIndicator, lv_palette_main(LV_PALETTE_GREEN), 0);
  } else {
    lv_label_set_text(wifiIndicator, "📶 WiFi 断开");
    lv_obj_set_style_text_color(wifiIndicator, lv_palette_main(LV_PALETTE_RED), 0);
  }

  // 更新 MQTT 状态
  if (mqttClient.connected()) {
    lv_label_set_text(mqttIndicator, "🔗 MQTT 已连接");
    lv_obj_set_style_text_color(mqttIndicator, lv_palette_main(LV_PALETTE_GREEN), 0);
  } else {
    lv_label_set_text(mqttIndicator, "🔗 MQTT 断开");
    lv_obj_set_style_text_color(mqttIndicator, lv_palette_main(LV_PALETTE_RED), 0);
  }
}

Main Loop Integration

Complete Main Loop

void setup() {
  Serial.begin(115200);

  // 连接 WiFi
  WiFi.begin("SSID", "PASSWORD");
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
  }

  // 初始化 LVGL 和屏幕
  lv_init();
  init_display();
  init_touch();
  create_ui();

  // MQTT 配置
  mqttClient.setServer(mqttServer, mqttPort);
  mqttClient.setCallback(mqttCallback);
  connectMQTT();
}

void loop() {
  // MQTT 保活
  if (!mqttClient.connected()) {
    connectMQTT();
  }
  mqttClient.loop();

  // LVGL 任务处理
  lv_timer_handler();

  // 状态更新
  static unsigned long lastStatusUpdate = 0;
  if (millis() - lastStatusUpdate > 1000) {
    lastStatusUpdate = millis();
    update_connection_indicators();
  }

  delay(5);
}

故障排除

问题 1: MQTT 消息丢失

原因: QoS 等级过低或网络不稳定

解决方案:

// 对关键控制命令使用 QoS 1
mqttClient.publish("home/light/livingroom/set", payload, true);  // retained = true

// 订阅时指定 QoS 1
mqttClient.subscribe("home/light/livingroom/status", 1);

问题 2: UI 更新不及时

原因: LVGL 定时器处理间隔过长

解决方案: 使用定时器实现周期性 UI 刷新

// LVGL 定时器
lv_timer_t* uiRefreshTimer = lv_timer_create(ui_refresh_cb, 100, NULL);

void ui_refresh_cb(lv_timer_t* timer) {
  // 更新传感器数据
  update_sensor_display();
}

Summary

本节介绍了智能家居面板的 MQTT 通信：

1. Topic 设计：分层的智能家居 Topic 结构（房间/设备/功能）
2. MQTT 集成：面板状态发布、远程命令订阅和 UI 更新
3. 触摸到 MQTT：触摸操作通过 MQTT 控制智能家居设备
4. 状态同步：WiFi/MQTT 连接状态实时显示
5. UI 数据绑定：MQTT 消息驱动 LVGL UI 更新