# 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
* 始動直後のスリープ遷移
* setup()で始動することに不都合がある処理

{% 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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