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setup() 只运行一次

准备引脚和串口的启动代码块

setup() 只运行一次 是 CoddyKit 上的免费 Arduino & IoT Academy 课时。这是第 1 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。

Two Blocks, Every Sketch

Every Arduino program is built from two functions. The first one is setup(), and getting it right makes everything else click. 🙂

Runs Exactly Once

The big idea: setup() runs a single time, right after your board powers on or resets. It never repeats on its own.

What setup() Looks Like

It is a function with empty parentheses and curly braces. Everything you write between those braces is your startup code.

void setup() {
  // startup code goes here
}

Why void?

The word void means setup returns no value. You are just running commands, not handing a result back to anyone.

Prepare Your Pins

setup is where you announce how each pin behaves. Use pinMode() once here so the board knows a pin sends or receives signals.

void setup() {
  pinMode(13, OUTPUT);
}

Open the Serial Channel

Talking to your computer also starts here. Serial.begin() opens the USB link once, ready for messages later.

void setup() {
  Serial.begin(9600);
}

One-Time Jobs Only

Put things here that should happen a single time: setting pin modes, starting Serial, or initializing a sensor. Setup is your launch checklist.

It Runs First, Always

No matter what else is in your sketch, setup() always runs before any repeating logic. It is the very first thing the board does.

Reset Triggers It Again

Press the board's reset button or cut and restore power, and setup() fires once more. A fresh start means a fresh setup.

Combine Several Lines

You can stack many one-time tasks inside setup. The board runs them top to bottom, then moves on for good.

void setup() {
  pinMode(13, OUTPUT);
  Serial.begin(9600);
}

Empty Is Still Valid

A sketch can have an empty setup() if nothing needs preparing. The braces must still be there, even with nothing inside.

void setup() {
}

Quick Check

Let's test how setup() behaves.

Recap: setup()

You learned that setup() runs once at startup, returns void, and is where you prepare pins and Serial. It is your board's launch checklist. 🎉

常见问题解答

「setup() 只运行一次」课时是免费的吗？

是的 — 「setup() 只运行一次」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。

「setup() 只运行一次」这节课中我会学到什么？

准备引脚和串口的启动代码块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 1 节课，共 4 节。

「setup() 只运行一次」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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