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Display temperature from BMP180 as Bargraph on LCD

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Display BMP180 Temperature as bargraph on LCD using Arduino

This video explains how to dispaly temperature measured with BMP180 as bargraph on LCD1602-I2C and LCD2014-I2C display..
  1. Robojax LCD Bargraph Libaray (zip file)
  2. I2C Scanner
  3. Introduction to LCD1602-I2C with code
  4. Introduction to BMP180 sensor
  5. Arduino You Know Course on Udemy

 /* Display temperature from BMP180 as Bargraph on LCD 
 *  Original Sources: 
 *  BMP180 library from https://www.sparkfun.com/products/11824
 *  LCD library: https://github.com/fdebrabander/Arduino-LiquidCrystal-I2C-library
 *  Bargraph library from https://playground.arduino.cc/Code/LcdBarGraph/
 *  Written and Update by Ahmad Shamshiri on June 05, 2019
 *  for Robojax in Ajax, Ontario
  Watch Video tutorial for this code : https://youtu.be/0IojNYgDD7U
  if you need the schematic diagram of this circuit, please visit  http://bit.ly/rj-udemy

* Robojax Arduino Course on Udemy where  you get Schematic Diagram of this sketch 
 * and many other robotics related lectures and codes. Purchase the course here: http://bit.ly/rj-udemy

- (GND) to GND
+ (VDD) to 3.3V

(WARNING: do not connect + to 5V or the sensor will be damaged!)


#include <SFE_BMP180.h>
#include <Wire.h>

SFE_BMP180 rjt;// creating object called "rjt" (robojax temperature)
#define UNIT 'C' // unit type C for Celsius F for Fahrenheit
#define maxTemperature 40 // is the value in Celsius or Fahrenheit set in line above

// LCD settings
#include <LiquidCrystal_I2C.h>
byte lcdNumCols = 16; // -- number of columns in the LCD
byte lcdLine = 2; // -- number of line in the LCD

LiquidCrystal_I2C lcd(0x3f,lcdNumCols,lcdLine); //0x3f is address for I2C
                  // to get I2C address, run I2C Scanner. 
                  //Link is provided (in same page as this code) at http://robojax.com/learn/arduino
// bargraph settings
#include <LcdBarGraphRobojax.h>
LcdBarGraphRobojax robojax(&lcd, 16, 0, 0);  // -- creating 16 character long bargraph starting at char 0 of line 0 (see video)

void setup()
  Serial.begin(9600);//initialize serial monitor
 // -- initializing the LCD
  // Initialize the sensor (it is important to get calibration values stored on the device).

  if (rjt.begin())
   lcd.setCursor (0,1); //  
    lcd.print("BMP180 Bargraph");  
  }else {
    lcd.setCursor (0,1); //  
    lcd.print("BMP180 Failed"); 
    while(1); // Pause forever.
  // -- give use some time to read the text above
}// setup

void loop()
 // Robojax BMP180 Bargraph main loop

 robojax.clearLine(1);// clear line 1 to display fresh temperature
 float T = getTemp();// get the temperature
 float Tgraph=T;
 if(T !=999){
     if( Tgraph > maxTemperature){   
        Tgraph =0;
        robojax.drawValue( Tgraph, maxTemperature);// draw the bargraph     
      // Print out the measurement:
      Serial.print("temperature: ");

      lcd.setCursor (0,1); //
      if(T< maxTemperature){       
      lcd.setCursor (7,1); //
      lcd.print(T); // print  
      lcd.print((char)223);// prints degree symbol
      if(UNIT =='C'){
        Serial.println(" deg C");         
        Serial.println(" deg F");         

    Serial.print("Status error");
      lcd.setCursor (0,1); //
      lcd.print("Error ");     


 * @brief gets the temperature  celsius or in farenheit
 * @param unit, should be capital C or capital F, C=celsius F=farenheit
 * @return celsius or in farenheit
 * Written by Ahmad Shamshiri for Robojax.com 
 * on Wednesday Jun 5th, 2019 at 22:30 in Ajax, Ontatio, Canada
double getTemp(){
    char status;
  double Temp,newTemp;
status = rjt.startTemperature();
  if (status != 0)
    // Wait for the measurement to complete:

    // Retrieve the completed temperature measurement:
    // Note that the measurement is stored in the variable T.
    // Function returns 1 if successful, 0 if failure.

    status = rjt.getTemperature(Temp);
    if (status != 0)
      if (UNIT =='F')
        newTemp = (9.0/5.0)*Temp+32.0;// convert to degrees farenheit
        newTemp = Temp;// keeps degree celsius
    return newTemp;    
    return 999;// if error, then retuen 999


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