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Display temperature from BMP180 as Bargraph on LCD

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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