如何从 DHT11 和 ESP8266 获得准确的温度和湿度值

Question

I would like to measure the temperature and humidity from DHT11 sensor and ESP8266. To do so, I made some code by using two libraries.

But none of these can give me an accurate number of humidity and temperature value. All I can get an output are like followings.

Temperature = 21.0000 Humidity = 48.0000

Please give me a hint to upgrade my code.

First code

#include <DHTesp.h>

DHTesp dht;

void setup(){

  Serial.begin(9600);
  pinMode(0, INPUT);
  dht.setup(0, DHTesp::DHT11);
}
void loop(){
  Serial.print("Temperature = ");
  Serial.println(dht.getTemperature(), 4);
  Serial.print("Humidity = ");
  Serial.println(dht.getHumidity(), 4);
  delay(1000);
}

Seconde code

#include <DHT.h>
DHT dht(0, DHT11);


void setup() {
  Serial.begin(9600);
  pinMode(0, INPUT);
  dht.begin();
}

void loop() {
 
    float humidity = dht.readHumidity();
    float temp = dht.readTemperature();
    delay(500);
    Serial.println(humidity);

}

Answer 1

From DHT11 datasheet , it only supports resolution to 1 degree Celsius and 8bits for humidity leading to the integer like floats.

Also something to keep in mind is the units that the DHT11 and DHT22 output.

Temperature is returned as Celsius and humidity is a value between 0 - 100 representing the relative humidity.

To convert between Celsius and Fahrenheit, you can use this formula

Serial.print((int)round(1.8*temp+32));