Crowtail- HTU21D Humidity&Temperature Sensor

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This module can help you detect the temperature and humidity of the environment of your house. The HTU21D is a low-cost, easy to use, highly accurate, digital humidity and temperature sensor. This sensor is ideal for environmental sensing and data logging and perfect for a weather stations or humidor control systems. All you need is two lines for I2C communication and you’ll have relative humidity readings and very accurate temperature readings as a bonus!

Model:Crowtail- Temperature& Humidity Sensor

Crowtail-Temperature& Humidity Sensor.JPG


  • Work Voltage: 3.3V ~ 5V
  • Measuring Range:

Humidity: 20% - 90% RH

Temperature: 0 ~ 50 °C

  • Accuracy:

Humidity: ±5% RH

Temperature: ±2°C

  • Sensitivity:

Humidity: ±1% RH

Temperature: 1°C

  • Signal Collecting Period: 2S


This demo is going to show you how to read temperature and humidity information from this Crowtail - Temperature and Humidity Sensor.

1.Hardware Connection
The Temperature and Humidity sensor is connecting to digital port D5 of Crowtail - Base Shield.

Temperature and Humidity Sensor.jpg

2.Download Temperature_humidity_sensor library for Arduino boards with 16MHz XTAL; Unzip and put it in the libraries file of Arduino IDE by the path: ..\arduino-1.0\libraries;

3.Open “DHTtester” example via the path: File --> Examples --> Humidity_Temperature_Sensor --> DHTtester.

// Example testing sketch for various DHT humidity/temperature sensors

#include "DHT.h"
#define DHTPIN 5     // what pin we're connected to
// Uncomment whatever type you're using!
#define DHTTYPE DHT11   // DHT 11 
//#define DHTTYPE DHT22   // DHT 22  (AM2302)
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor


void setup() {
  Serial.println("DHTxx test!");
void loop() {
 // Reading temperature or humidity takes about 250 milliseconds!
 // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
 float h = dht.readHumidity();
 float t = dht.readTemperature();

 // check if returns are valid, if they are NaN (not a number) then something went wrong!
 if (isnan(t) || isnan(h)) {
   Serial.println("Failed to read from DHT");
 } else {
   Serial.print("Humidity: "); 
   Serial.print(" %\t");
   Serial.print("Temperature: "); 
   Serial.println(" *C");

4.Upload it into your Arduino board and open the serial monitor to observe the temperature and relative humidity information of the environment.



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