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Lesson 36: Using HTU21D Temperature Sensor with LCD| Arduino Step by Step Course

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Part 4: Temperature Sensors

In this lesson we learn how to use HTU21D Temperature sensor to measure and display LCD1602 and LCD2004. There is introduction video and code you must watch.


 /*
 * Robojax Arduino Step By Step Course
 * Part 4: Temperature Sensors
 * Lesson 36: HTU21D Temperature Sensor with LCD1602 and LCD2004 Display
 


 * Display Temperature from HTU21DF on LCD1602-I2C or LCD2004
 * Updated by Ahmad Shamshiri on July 13, 2019


 
  Please watch video instruction here https://youtu.be/SrFJKbmiaPM
 This code is available at http://robojax.com/course1/?vid=lecture36
 
with over 100 lectures Free On  YouTube Watch it here http://robojax.com/L/?id=338
Get the code for the course: http://robojax.com/L/?id=339  

If you found this tutorial helpful, please support me so I can continue creating 
 make donation using PayPal http://robojax.com/L/?id=64



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

  Designed specifically to work with the HTU21D-F sensor from Adafruit
  ----> https://www.adafruit.com/products/1899

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

 Watch Introduction to  360 Servo video with code: https://youtu.be/b_xvu6wWafA
You can get the wiring diagram from my Arduino Course at Udemy.com
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content like this. You can support me on Patreon http://robojax.com/L/?id=63
or make donation using PayPal http://robojax.com/L/?id=64

 * Code is available at http://robojax.com/learn/arduino

 * 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 Robojax.com
    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
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    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 <https://www.gnu.org/licenses/>. 

*/

#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();

// start of settings for LCD1602 with I2C
#include <LiquidCrystal_I2C.h>
// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x3F, 16, 2);
// end of settings for LCD1602 with I2C

void setup() {
	//Get the code for the course: http://robojax.com/L/?id=339  
  lcd.begin();  
  lcd.backlight();
  if (!htu.begin()) {
      lcd.print("Robojax HTUD1DF");
      lcd.setCursor(0,1);
      lcd.print("sensor missing"); 
    while (1);
  }else{
  // initialize the LCD

  lcd.print("Robojax HTUD1DF");
  lcd.setCursor(0,1);
  lcd.print("Demo"); 
  }
  delay(2000);   
}

void loop() {
//Get the code for the course: http://robojax.com/L/?id=339  	
   lcd.clear();// clear previous values from screen
lcdDisplay(
             // to print Celsius:
             0, // character 0 
             0, // line 0
             "Celsius: ", 

             // to print Celsius
             10, // character 10
             0, // line 0
             getHTU('C'),
             'd'
             );  

  lcdDisplay(
             // to print fahrenheit:
             0, // character 0 
             1, // line 1
             "Fahrenh.: ", 

             // to print Fahrenheit
             10, // character 9
             1, // line 0
             getHTU('F'),
             'd'
             );     
    delay(5000);
lcdDisplay(
             // to print Kelvin:
             0, // character 0 
             0, // line 0
             "Kelvin: ", 

             // to print Celsius
             9, // character 10
             0, // line 0
             getHTU('K'),
             'k'
             );      
  lcdDisplay(
             // to print humidity text
             0, // character 0 
             1, // line 1
             "Humidity.: ", 

             // to print humidity
             10, // character 9
             1, // line 1
             getHTU('H'),
             '%' 
             );  
   
        delay(5000);
}

/*
 * @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
 * www.Robojax.com 
 */
float getHTU(char type)
{
	//Get the code for the course: http://robojax.com/L/?id=339  
  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
   }else{
    value = temp;// return Celsius
   }
   return value;
}//


/*
 * lcdDisplay(int tc, int tr, String title, int vc, int vr, float value)
 * displays value and title on LCD1602
 * How to use:
 * If you wan to diaplay: "Voltage: 13.56mV" starting from first character
 * on second row.
 * use:
 * lcdDisplay(0, 1, "Voltage: ", 13.56,'d')
 *   
 *   'd' is degree symbol
 * tc  is character number  (0)
 * tr is row in the lcd (1)
 * title is the text (Voltage:)
 * vc value for character 
 * vr value for  row or line
 * value is the value (13.56)
 */
void lcdDisplay(int tc, int tr, String title, int vc, int vr, float value,char symbol)
{
   // Robojax.com LCD1602 for HTU21D Demo
   lcd.setCursor (tc,tr); //
   lcd.print(title);
   
   lcd.setCursor (vc,vr); //
   lcd.print(value);
   if(symbol == 'd')
   {
    lcd.print((char)223);
   }else if(symbol =='%')
   {
    lcd.print("%");
   }else if(symbol =='k')
   {
    lcd.print("K");
   }
 // Robojax.com LCD1602 for HTU21D Demo
} 



   

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