> For the complete documentation index, see [llms.txt](https://mwx.twelite.info/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mwx.twelite.info/v0.1.7/api-reference/functions/begin.md).

# begin()

`loop()`関数の初回コールの手前で一度だけ呼び出されます。TWENET の初期化は終了しているので`setup()`のような制約を考慮する必要はありません。

主な使い方は、

* 始動メッセージの表示
* テスト用のコードを記述
* 始動直後のスリープ遷移
* `setup()`で不都合がある処理（無線パケット処理・タイマー動作など）

{% hint style="info" %}
このコールバック関数定義は省略可能です。
{% endhint %}


---

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