Example sketch for DS18B20 temperature sensors using the DallasTemperature library. Prints results to an I2C LCD.

DS18B20_LCD_demo.ino

/*
 Demonstration sketch for DS18B20 temperature sensors using the DallasTemperature library.
 
 Reads temperature (Celsius) and temperature (Fahrenheit). Displays results to I2C LCD.
*/

#include <LCD.h>                  // I2C LCD
#include <Wire.h>                 // I2C
#include <OneWire.h>              // One-wire devices
#include <DallasTemperature.h>    // DS18B20

#define    DS18B20_BUS     A0     // Dallas DS18B20 temperature sensors

const char degree = 223;          // Degree symbol

/*-----------------------------------------------------------------------------------------------
 * Create object references
 * ----------------------------------------------------------------------------------------------*/

// create LCD object
LCD lcd;

// Setup One-wire instance to communicate with DS18B20 sensors
OneWire  oneWire(DS18B20_BUS);

// Pass oneWire reference to DallasTemperature library
DallasTemperature  temperatureSensors(&oneWire);

// Create an array for DS18B20 sensor addresses
DeviceAddress  DS18B20[3]; 

/*-----------------------------------------------------------------------------------------------
 * Function: INIT_DS18B20
 * Description: Initialize DS18B20 Temperature sensor(s)
 * Ins: Integer value for sensor precision.  Can be 9, 10, 11 or 12 bits
 * Outs: none
 * ----------------------------------------------------------------------------------------------*/
 
void INIT_DS18B20(int precision)
{
  temperatureSensors.begin();

  int available = temperatureSensors.getDeviceCount();

  for(int x = 0; x!= available; x++)
  {
    if(temperatureSensors.getAddress(DS18B20[x], x))
    {
      temperatureSensors.setResolution(DS18B20[x], precision);
    }
  }
}

/*-----------------------------------------------------------------------------------------------
 * Function: DS18B20_CELSIUS
 * Description: Get celsius reading from DS18B20 Temperature sensor
 * Ins: Integer value for sensor address
 * Outs: Returns celsius reading
 * ----------------------------------------------------------------------------------------------*/
 
int DS18B20_CELSIUS(int address)
{
  if (temperatureSensors.getAddress(DS18B20[address], address))
  {
    temperatureSensors.requestTemperatures();
    return temperatureSensors.getTempC(DS18B20[address]);
  }
  else
    return 0;
}

/*-----------------------------------------------------------------------------------------------
 * Function: DS18B20_FAHRENHEIT
 * Description: Get fahrenheit reading from DS18B20 Temperature sensor
 * Ins: Integer value for sensor address
 * Outs: Returns fahrenheit reading
 * ----------------------------------------------------------------------------------------------*/
 
int DS18B20_FAHRENHEIT(int address)
{
  if (temperatureSensors.getAddress(DS18B20[address], address))
  {
    temperatureSensors.requestTemperatures();
    return DallasTemperature::toFahrenheit(temperatureSensors.getTempC(DS18B20[address]));
  }
  else
    return 0;
}

/*-----------------------------------------------------------------------------------------------
 * Main routines
 * ----------------------------------------------------------------------------------------------*/

void setup()
{
  // Initialize DS18B20 temperature sensors with precision set to 9
  INIT_DS18B20(9);
  
  // Initialize LCD to 20 characters by 4 lines
  lcd.begin(20, 4);
     
  lcd.clear();
  
  lcd.print("--DS18B20 Demo--");
    
  lcd.setCursor(0, 1);
  lcd.print("Temp C: ");
  
  lcd.setCursor(0, 2);
  lcd.print("Temp F: ");
}

void loop()
{
  float temp_c;
  float temp_f;

  // Read values from the sensor at address 0
  temp_c = DS18B20_CELSIUS(0);
  temp_f = DS18B20_FAHRENHEIT(0);

  // Print results to LCD
  lcd.setCursor(10, 1);
  lcd.print(temp_c);
  lcd.print(degree);
  lcd.print("C");
  
  lcd.setCursor(10, 2);
  lcd.print(temp_f);
  lcd.print(degree);
  lcd.print("F");

  delay(1000);
}

Can anyone tell me where it says in the code or anywhere as to what pin to wire the 18B20 sensor?

is this line of code below saying the sensor is connected to pin 9?
// Initialize DS18B20 temperature sensors with precision set to 9
does anyone monitor this page?

Hello,

The 1-Wire bus line is connected to Pin A0 and is defined in the code in this line:

define DS18B20_BUS A0 // Dallas DS18B20 temperature sensors

Hope this helps.

How is posible, add more DS18B20 sensors? I need add 2 sensors, but no more pins availables. I use a Wemos D1 R2 card.