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arduino-sht

Repository for Sensirion humidity and temperature sensor support on Arduino

Supported sensors:

  • SHTC1
  • SHTW1
  • SHTW2
  • SHT3x-DIS (I2C)
  • SHT3x-ARP (ratiometric analog voltage output)

Installation

Download arduino-sht either via git or from the releases page and place it in your Arduino/libraries directory. After restarting the Arduino IDE, you will see the new SHTSensor menu items under libraries and examples.

Integrating it into your sketch

Assuming you installed the library as described above, the following steps are necessary:

  1. Import the Wire library like this: From the menu bar, select Sketch > Import Library > Wire
  2. Import the arduino-sht library: From the menu bar, select Sketch > Import Library > arduino-sht
  3. Create an instance of the SHTSensor class (SHTSensor sht;)
  4. In setup(), make sure to init the Wire library with Wire.begin()
  5. If you want to use the serial console, remember to initialize the Serial library with Serial.begin(9600)
  6. Call sht.readSample() in the loop() function, which reads a temperature and humidity sample from the sensor
  7. Use sht.getHumidity() and sht.getTemperature() to get the values from the last sample

Important: getHumidity() and getTemperature() do not read a new sample from the sensor, but return the values read last. To read a new sample, make sure to call readSample()

Sample code

#include <Wire.h>

#include <SHTSensor.h>

SHTSensor sht;

void setup() {
  // put your setup code here, to run once:

  Wire.begin();
  Serial.begin(9600);
  sht.init();
}

void loop() {
  // put your main code here, to run repeatedly:

  sht.readSample();
  Serial.print("SHT:\n");
  Serial.print("  RH: ");
  Serial.print(sht.getHumidity(), 2);
  Serial.print("\n");
  Serial.print("  T:  ");
  Serial.print(sht.getTemperature(), 2);
  Serial.print("\n");

  delay(1000);
}

Usage with two SHT31 sensors

#include <Wire.h>
#include "SHTSensor.h"

// Sensor with normal i2c address
// Sensor 1 with address pin pulled to GND
SHTSensor sht1(SHTSensor::SHT3X);

// Sensor with alternative i2c address
// Sensor 2 with address pin pulled to Vdd
SHTSensor sht2(SHTSensor::SHT3X_ALT);

void setup() {
  // put your setup code here, to run once:
  Wire.begin();
  Serial.begin(9600);
  delay(1000); // let serial console settle

  // init on a specific sensor type (i.e. without auto detecting), 
  // does not check if the sensor is responding and will thus always succeed.

  // initialize sensor with normal i2c-address
  sht1.init();

  // initialize sensor with alternative i2c-address
  sht2.init();
}
void loop() {
  // put your main code here, to run repeatedly:
  // read from first sensor
  if (sht1.readSample()) {
    Serial.print("SHT1 :\n");
    Serial.print("  RH: ");
    Serial.print(sht1.getHumidity(), 2);
    Serial.print("\n");
    Serial.print("  T:  ");
    Serial.print(sht1.getTemperature(), 2);
    Serial.print("\n");
  } else {
    Serial.print("Sensor 1: Error in readSample()\n");
  }
  // read from second sensor
  if (sht2.readSample()) {
    Serial.print("SHT2:\n");
    Serial.print("  RH: ");
    Serial.print(sht2.getHumidity(), 2);
    Serial.print("\n");
    Serial.print("  T:  ");
    Serial.print(sht2.getTemperature(), 2);
    Serial.print("\n");
  } else {
    Serial.print("Sensor 2: Error in readSample()\n");
  }
  delay(1000);
}