IoT 入门指南 IoT Beginner Guide

物联网（Internet of Things, IoT）是指将日常设备连接到互联网，让它们能够收集和分享数据的技术。简单来说，就是让"东西"变得"智能"。

现实中的物联网

• 智能家居 (Smart Home)：用手机远程控制灯光、空调、门锁
• 可穿戴设备 (Wearables)：智能手表监测心率、步数、睡眠
• 工业传感器 (Industrial Sensors)：工厂设备实时监控温度、压力、振动
• 智慧农业 (Smart Agriculture)：土壤湿度传感器自动灌溉

关键术语 (Key Terms)

The Internet of Things (IoT) is the practice of connecting everyday devices to the internet so they can collect and share data. In short — making "things" smart.

IoT in the real world

• Smart Home — control lights, AC, and door locks from your phone
• Wearables — smartwatches tracking heart rate, steps, and sleep
• Industrial Sensors — factory equipment monitoring temperature, pressure, and vibration in real time
• Smart Agriculture — soil moisture sensors triggering automatic irrigation

Key Terms

传感器 (Sensors)

传感器是物联网的"感官"，负责检测环境中的物理量并转换为电信号。

• 温湿度传感器：DHT22、SHT30 — 测量温度和湿度
• 光照传感器：BH1750 — 测量环境光强度（勒克斯 lux）
• 距离传感器：HC-SR04 超声波 — 测量物体距离
• 存在传感器：RCWL-0516 毫米波 — 检测人体存在

执行器 (Actuators)

执行器是物联网的"手脚"，根据指令执行物理动作。

• LED — 最简单的输出设备，指示状态
• 继电器 (Relay) — 控制高电压设备（如电灯、风扇）
• 电机 (Motor) — 伺服电机、步进电机、直流电机
• 蜂鸣器 (Buzzer) — 发出声音提醒

微控制器基础 (MCU Basics)

数据流 (Data Flow)

一个典型的物联网系统数据流：

关键术语 (Key Terms)

Sensors

Sensors are the "senses" of an IoT system — they detect physical quantities and convert them into electrical signals.

• Temperature / humidity — DHT22, SHT30 measure temperature and humidity
• Light — BH1750 measures ambient light in lux
• Distance — HC-SR04 ultrasonic sensor measures object distance
• Presence — RCWL-0516 millimeter-wave radar detects human presence

Actuators

Actuators are the "hands and feet" of IoT — they perform physical actions on command.

• LED — the simplest output, indicates status
• Relay — switches high-voltage devices like lights and fans
• Motor — servos, steppers, DC motors
• Buzzer — audio alerts

MCU Basics

Data Flow

A typical IoT system pipeline:

Key Terms

步骤 1：连接硬件

将 DHT22 传感器连接到 ESP32：

• DHT22 VCC → ESP32 3.3V
• DHT22 GND → ESP32 GND
• DHT22 DATA → ESP32 GPIO 4（加 10kΩ 上拉电阻）

步骤 2：读取传感器数据

使用 Arduino DHT 库读取温湿度值。安装库：Sketch → Include Library → Manage Libraries → 搜索 "DHT sensor library"。

步骤 3：连接 WiFi

使用 ESP32 内置的 WiFi 库连接到你的家庭网络。将 WiFi 名称和密码写入代码。

步骤 4：发送 MQTT 数据

使用 PubSubClient 库连接 MQTT Broker，将温湿度数据发布到 home/living-room/temp 和 home/living-room/humidity 主题。

步骤 5：查看数据

在手机上安装 MQTT Dashboard 应用（如 IoT MQTT Panel），订阅相同主题，即可实时查看数据。

常见问题 (Troubleshooting)

• 传感器读数为 NaN — 检查接线，确认上拉电阻已连接
• WiFi 连接失败 — 确认密码正确，ESP32 仅支持 2.4GHz WiFi
• MQTT 连接超时 — 检查 Broker 地址和端口（默认 1883）

关键术语 (Key Terms)

Step 1: wire the hardware

Connect the DHT22 to the ESP32:

• DHT22 VCC → ESP32 3.3V
• DHT22 GND → ESP32 GND
• DHT22 DATA → ESP32 GPIO 4 (with a 10kΩ pull-up resistor)

Step 2: read sensor data

Use the Arduino DHT library to read temperature and humidity. Install it: Sketch → Include Library → Manage Libraries → search for "DHT sensor library".

Step 3: connect to WiFi

Use the ESP32's built-in WiFi library to connect to your home network. Put your WiFi SSID and password in the code.

Step 4: publish MQTT data

Use the PubSubClient library to connect to the MQTT broker and publish temperature and humidity to the topics home/living-room/temp and home/living-room/humidity.

Step 5: view the data

Install an MQTT Dashboard app on your phone (e.g. IoT MQTT Panel), subscribe to the same topics, and watch the data stream in.

Troubleshooting

• Sensor reads NaN — check wiring; confirm the pull-up resistor is connected
• WiFi won't connect — verify the password; ESP32 only supports 2.4GHz WiFi
• MQTT connection times out — check the broker address and port (default 1883)

Key Terms