Back to Step by Step Course by Robojax

Lesson 35: Using HTU21D Temperature Sensor | Arduino Step by Step Course

If you don't like to see ads while video is being played you can purchase YouTube premium Here

Please select other codes for this lecture from the links below.

Related or required files and link to this lesson

Part 4: Temperature Sensors

In this lesson we learn how to use HTU21D Temperature sensor to measure and display it Serial monitor. There are two other video lectures for this sensor 1-Using it with LCD 2--Using as bargraph

 * Robojax Arduino Step By Step Course
 * Part 4: Temperature Sensors
 * Lesson 35: HTU21D Temperature Sensor

 * Updated by Ahmad Shamshiri on July 13, 2019
 * in Ajax, Ontario, Canada

  Please watch video instruction here
 This code is available at
with over 100 lectures Free On  YouTube Watch it here
Get the code for the course:  
If you found this tutorial helpful, please support me so I can continue creating 
 make donation using PayPal

 * Code is available at

 * This code is "AS IS" without warranty or liability. Free to be used as long as you keep this note intact.* 
 * This code has been download from
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <>. 

  This is an example for the HTU21D-F Humidity & Temp Sensor

  Designed specifically to work with the HTU21D-F sensor from Adafruit

  These displays use I2C to communicate, 2 pins are required to

#include <Wire.h>
#include "Adafruit_HTU21DF.h"

// Connect Vin to 3-5VDC
// Connect GND to ground
// Connect SCL to I2C clock pin (A5 on UNO)
// Connect SDA to I2C data pin (A4 on UNO)

Adafruit_HTU21DF htu = Adafruit_HTU21DF();

void setup() {
  Serial.println("HTU21D-F test");

  if (!htu.begin()) {
    Serial.println("Couldn't find sensor!");
    while (1);

void loop() {
//Get the code for the course:  

    Serial.println(" ");  


    if(getHTU('C') <81)
      //digitalWrite(5, LOW);

 * @brief returns temperature or relative humidity
 * @param "type" is character
 *     C = Celsius
 *     K = Keliven
 *     F = Fahrenheit
 *     H = Humidity
 * @return returns one of the values above
 * Usage: to get Fahrenheit type: getHTU('F')
 * to print it on serial monitor Serial.println(getHTU('F'));
 * Written by Ahmad Shamshiri on July 13, 2019
 * in Ajax, Ontario, Canada
float getHTU(char type)
	//Get the code for the course:  
  float value;
    float temp = htu.readTemperature();
    float rel_hum = htu.readHumidity();
   if(type =='F')
    value = temp *9/5 + 32;//convert to Fahrenheit 
   }else if(type =='K')
    value = temp + 273.15;//convert to Kelvin
   }else if(type =='H')
    value = rel_hum;//return relative humidity
    value = temp;// return Celsius
   return value;

 * @brief prints degree symbol on serial monitor
 * @param none
 * @return returns nothing
 * Written by Ahmad Shamshiri on JUly 13, 2019
 * for Robojax Tutorial
void printDegree()


The least I expect from you is to thumb up the video and subscribe to my channel. I appriciate that. .I have spent months making these lectures and writing code. You don't lose anything by subscribging to my channel. Your subscription is stamp of approval to my videos and more people can find them and in it turn it helps me. Thank you

If you found this tutorial helpful, please support me so I can continue creating content like this. support me via PayPal

**** AFFILIATE PROGRAM **** We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.

Right Side