DHT11 温湿度传感器项目：LED 指示与压电蜂鸣器报警

组件与物料

• DHT11 温湿度传感器（4 引脚）×1
• LED ×3（绿×1、红×2）
• 220 Ω 电阻 ×3
• 压电蜂鸣器 ×1
• Arduino UNO ×1
• 杜邦线若干

软件与库

• Arduino IDE
• Adafruit_Sensor 库：GitHub
• DHT_sensor_library：GitHub

项目功能

实时读取温湿度，通过三色 LED 指示温度区间：

• ≤ 20 °C：蓝 LED 亮 + 蜂鸣器短鸣 1 s（过冷）
• 20–27 °C：绿 LED 亮 2 s（舒适）
• ≥ 29 °C：红 LED 亮 + 蜂鸣器短鸣 1 s（过热）

串口每 2 秒打印一次温湿度数值。

接线说明

• DHT11 DATA → D5
• 蓝 LED (过冷) → A0
• 绿 LED (舒适) → A1
• 红 LED (过热) → A2
• 蜂鸣器 → D9
• 所有 LED 串 220 Ω 电阻接地

完整代码

#include 
#include 

#define DHTPIN 5
#define DHTTYPE DHT11
#define LED_COLD A0
#define LED_OK   A1
#define LED_HOT  A2
#define BUZZER   9

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin();
  pinMode(LED_COLD, OUTPUT);
  pinMode(LED_OK,   OUTPUT);
  pinMode(LED_HOT,  OUTPUT);
  pinMode(BUZZER,   OUTPUT);
}

void loop() {
  delay(2000);
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
  Serial.print("Humidity: "); Serial.print(h); Serial.print(" %\t");
  Serial.print("Temp: "); Serial.print(t); Serial.println(" *C");

  if (t <= 20) {
    Serial.println("Too cold!");
    digitalWrite(LED_COLD, HIGH); digitalWrite(BUZZER, HIGH);
    delay(1000); digitalWrite(LED_COLD, LOW); digitalWrite(BUZZER, LOW);
  }
  else if (t < 27) {
    Serial.println("Perfect!");
    digitalWrite(LED_OK, HIGH); delay(2000); digitalWrite(LED_OK, LOW);
  }
  else if (t >= 29) {
    Serial.println("Too hot!");
    digitalWrite(LED_HOT, HIGH); digitalWrite(BUZZER, HIGH);
    delay(1000); digitalWrite(LED_HOT, LOW); digitalWrite(BUZZER, LOW);
  }
}