Si7021 is an integrated sensor that measures both temperature and relative humidity with good accuracy. The resolution of measured parameters can be selected through software between 8-12 bits for humidity and 12-14 bits for temperature. The sensor uses a digital I2C interface for data transmission, so we can easily interface with it using the Wire library.

Fig. 1: SI7020 and its connections to the the AVR microcontroller

We will need to use a dedicated library written specially for it. Download the library from here and unzip its contents into the folder named Arduino\libraries or use Arduino IDE's Add ZIP Library command.

#include <Wire.h>
#include <SHT2x.h>
 
int controlPin = 7;
 
void setup()
{
  pinMode(controlPin, OUTPUT);  //sensor on/off control
 
  Wire.begin();
  Serial.begin(9600);
 
  digitalWrite(controlPin, LOW); //enable all sensors
}
 
void loop()
{
 
 
  Serial.print("Humidity(%RH): ");
  Serial.print(SHT2x.GetHumidity());
  Serial.print("     Temperature(C): ");
  Serial.println(SHT2x.GetTemperature());
 
  //digitalWrite(controlPin, HIGH); //disable all sensors
 
  delay(1000);
}