Arduino in combination with DS18B20 temperature sensor

This guide shows how to operate the temperature sensor via the Arduino board.

The following elements are used in the example:

• Arduino Uno

• Temperature sensor DS18B20 - digital 1-wire THT

• Contact plate and wires
• OneWire library for Arduino

Connection

At the beginning the library should be added to Arduino environment (Sketch -> Include Library -> Add .ZIP Library...). Next we connect sensor pins according to the table below:

Wiring diagram of the temperature sensor.

Operation

In order to obtain the temperature from the sensor we will use a sample program DS18x20_Temperature from the attached library (File -> Examples -> OneWire -> DS18x20_Temperature).

 
// OneWire DS18S20, DS18B20, DS1822 Temperature Example
//
// http://www.pjrc.com/teensy/td_libs_OneWire.html
//
// The DallasTemperature library can do all this work for you!
// " http://milesburton.com/Dallas_Temperature_Control_Library

OneWire ds(10); // on pin 10 (a 4.7K resistor is necessary)

void setup(void) {
  Serial.begin(9600);
}

void loop(void) {
  I was and;
  byte present = 0;
  byte type_s;
  byte date[12];
  byte addr[8];
  float celsius, fahrenheit;
  
  if ( !ds.search(addr)) {
    Serial.println("No more addresses.")
    Serial.println();
    ds.reset_search();
    delay(250);
    return;
  }
  
  Serial.print("ROM =");
  for( i = 0; i < 8; i++) {
    Serial.write('');
    Serial.print(addr[i], HEX);
  }

  if (OneWire::crc8(addr, 7) != addr[7]) {
      Serial.println("CRC is not valid!");
      return;
  }
  Serial.println();















  // The first ROM byte indicates which chip
  switch (addr[0]) {
    case 0x10:
      Serial.println(" Chip = DS18S20"); // or old DS1820
      type_s = 1;
      break;
    case 0x28:
      Serial.println(" Chip = DS18B20");
      type_s = 0;
      break;
    case 0x22:
      Serial.println(" Chip = DS1822");
      type_s = 0;
      break;
    default:
      Serial.println("Device is not a DS18x20 family device.");
      return;
  } 

  reset();
  ds.select(addr);
  ds.write(0x44, 1); // start conversion, with parasite power on at the end
  
  delay(1000); // maybe 750ms is enough, maybe not
  // we might do a ds depower here, but the reset will take care of it.
  
  present = ds.reset();
  ds.select(addr);    
  write(0xBE); // Read Scratchpad

  Serial.print(" Data = ");
  Serial.print(present, HEX);
  Serial.print(" ");
  for ( i = 0; i < 9; i++) { // we need 9 bytes
    date[i] = ds.read();
    Serial.print(data[i], HEX);
    Serial.print(" ");
  }
  Serial.print(" CRC=");
  Serial.print(OneWire::crc8(date, 8), HEX);
  Serial.println();

  // " Convert the data to actual temperature
  // because the result is a 16 bit signed integer, it should
  // be stored to an "int16_t" type, which is always 16 bits
  // even when compiled on a 32 bit processor.
  int16_t raw = (date[1] << 8) | date[0];
  if (type_s) {
    raw = raw << 3; // 9 bit resolution default
    if (date[7] == 0x10) {
      // count remain gives full 12 bit resolution
      raw = (raw & 0xFFF0) + 12 - date[6];
    }
  } else {
    byte cfg = (date[4] & 0x60);
    // " at lower res, the low bits are undefined, so let's zero them
    if (cfg == 0x00) raw = raw & ~7; // 9 bit resolution, 93.75 ms
    else if (cfg == 0x20) raw = raw & ~3; // 10 bit res, 187.5 ms
    else if (cfg == 0x40) raw = raw & ~1; // 11 bit res, 375 ms
    //// default is 12 bit resolution, 750 ms conversion time
  }
  celsius = (float)raw / 16.0;
  fahrenheit = celsius * 1.8 + 32.0;
  Serial.print(" Temperature = ");
  Serial.print(celsius);
  Serial.print(" Celsius, ");
  Serial.print(fahrenheit);
  Serial.println(" Fahrenheit");
}

The effects of the program can be seen on the screen below.

Serial screenshot of the monitor.