# digitalRead

## 函数原型

```cpp
int digitalRead(uint8_t pin);
```

## 作用

读取指定引脚的电位

{% hint style="info" %}
在调用此函数之前要保证该引脚已经 `pinMode` 过，且为输入模式。
{% endhint %}

## 参数

* `pin`

  指定引脚的编号，如： `10` , `A0` 等。

## 返回值

* `int` 整型

  指定的引脚的电位

返回值有以下两种可能：

| 值      | 名称  | 介绍       |
| ------ | --- | -------- |
| `HIGH` | 高电平 | 引脚电压为 5V |
| `LOW`  | 低电平 | 引脚电压为 0V |

## 示例

```cpp
// 假设 4 号引脚连接的是 高电平
int state = digitalWrite(4);
// state = HIGH; 也就是 stats = 1;
```


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