Arduino & IoT Academy · 课时

连接并编写传感器节点代码

读取环境数据，并通过 MQTT 发布

连接并编写传感器节点代码 是 CoddyKit 上的免费 Arduino & IoT Academy 课时。这是第 2 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Arduino & IoT Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Arduino & IoT Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

Build the Node

现在，你要将方案转化为硬件。你需要将 DHT22 连接到 ESP32，并编写代码来读取气候数据并将其发布。🔌

Wire Power and Ground

将 DHT22 的 VCC 连接到 ESP32 的 3.3V 引脚，并将 GND 连接到地（GND）。共地是让两个部件在信号上保持一致的基础。

Wire the Data Pin

Run the sensor's data line to a GPIO pin and add a pull-up resistor so the idle line stays clean and reads reliably.

Include Your Libraries

At the top of the sketch, pull in the tools you need: the DHT library for the sensor and PubSubClient for MQTT.

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

Create the Sensor Object

Tell the library which pin and sensor type you used by creating a DHT object. This becomes your handle for every reading.

#define DHTPIN 4
DHT dht(DHTPIN, DHT22);

Start Things in setup()

In setup() you open Serial, start the sensor with dht.begin(), and connect to WiFi so the node is ready before the loop runs.

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

Read Temperature & Humidity

Each cycle, call readTemperature() and readHumidity() to grab fresh numbers from the room into two variables.

float t = dht.readTemperature();
float h = dht.readHumidity();

Guard Against Bad Reads

Sensors sometimes return NaN. Check isnan() and skip publishing that round so you never send junk to the cloud.

if (isnan(t) || isnan(h)) {
  return;
}

Connect to the Broker

Point PubSubClient at your broker's address and port, then keep a reconnect helper so a dropped link is rejoined automatically.

client.setServer(BROKER, 1883);

Publish a Reading

Send each value to its topic with client.publish(). The cloud now receives a fresh temperature every cycle.

client.publish("home/livingroom/temp", String(t).c_str());

Pace the Loop

Don't flood the network. Use millis() timing to publish about once every few seconds, which is plenty for room climate.

Quick Check

Test your sensor-node code.

Recap

You wired the DHT22, read clean values, guarded bad reads, and published them over MQTT. Your sensor node is alive and talking. 📡

常见问题解答

「连接并编写传感器节点代码」课时是免费的吗？

是的 — 「连接并编写传感器节点代码」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Arduino & IoT Academy 课程的其余内容，请升级到 CoddyKit PRO。 Arduino & IoT Academy 课程共包含 4 节课。

「连接并编写传感器节点代码」这节课中我会学到什么？

读取环境数据，并通过 MQTT 发布你通过在浏览器中直接运行的动手代码来练习 Arduino & IoT Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Arduino & IoT Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Arduino & IoT Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 2 节课，共 4 节。

「连接并编写传感器节点代码」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Arduino & IoT Academy 课中编写并运行代码吗？

能。每节 Arduino & IoT Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

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