Interfacing Multiple DS18B20 Temperature Sensors to Microcontroller

Interfacing Multiple DS18B20 Temperature Sensors to Microcontroller (Last Updated On: February 22, 2019)

Interfacing Multiple DS18B20 Temperature Sensors to Microcontroller:

In this project we will learn about Interfacing Multiple DS18B20 Temperature Sensors to Microcontroller ATmega328. Simply we will connect Multiple DS18B20 Temperature Sensors to Microcontroller pin and display the temperature values of all the sensors in degree celsius or Fahrenheit. Only one digital pin of Microcontroller ATmega328 is required to connect several temperature sensor. We can connect maximum of 1024 sensors using I2C Protocol. But here i have shown connecting 3 DS18B20 Temperature Sensors to Microcontroller ATmega328.



The DS18B20 temperature sensor is a 1-wire digital temperature sensor. This comes with sealed package lets precisely measure temperatures in wet environments with a simple 1-Wire interface. It communicates on common bus. It means it can connect several devices and read their values using just one digital pin of the Microcontroller.


DS18B20 Waterproof Digital Temperature Sensor:

This is a pre-wired and waterproofed version of the DS18B20 sensor. Handy for when you need to measure something far away, or in wet conditions. The Sensor can measure the temperature between -55 to 125°C (-67°F to +257°F). The cable is jacketed in PVC.

Because it is digital, there is no any signal degradation even over long distances. These 1-wire digital temperature sensors are fairly precise, i.e ±0.5°C over much of the range. It can give up to 12 bits of precision from the onboard digital-to-analog converter. They work great with any microcontroller using a single digital pin.

DS18B20 Temperature Sensors to Microcontroller

The only downside is they use the Dallas 1-Wire protocol, which is somewhat complex, and requires a bunch of code to parse out the communication. We toss in a 4.7k resistor, which is required as a pullup from the DATA to VCC line when using the sensor.


Components Required:

1. ATmega328 Microcontroller (Buy Online from Amazon)
2. Multiple DS18B20 Waterproof Temperature Sensor (Buy Online from Amazon)
3. 16*2 LCD Display
4. 4.7K, 1M & 100 ohm Resistors
5. 22pF, 10uF & 22pF Capacitors
6. 16 MHz Crystal Oscillator
7. 5 Volt Power Supply or Battery



Circuit Diagram & Connections:

Interfacing Multiple DS18B20 Temperature Sensors to Microcontroller


Hardware & Design:

By connecting all the sensors to one digital pin of Microcontroller ATmega328 we have simply designed Digital Thermometer for measuring multiple temperature. So the below picture tells how we have Interfaced Multiple DS18B20 Temperature Sensors to Microcontroller ATmega328 and how the temperature is being displayed.



Source Code/Program:

We have used Arduino Language to write the code and upload it to microcontroller. Take a fresh ATmega328 and insert it into Arduino UNO Board. First upload the bootloader. Then simply compile the below code and upload it to microcontroller. Now you can remove the microcontroller and insert it into PCB.

For interfacing Multiple DS18B20 Temperature Sensors to ATmega328 microcontroller you need two different library
1. Download 1 Wire Library
2. Download Dallas Temperature Library



Working of Multiple DS18B20 Temperature Sensors with Microcontroller:

The DS18B20 provides 9 to 12-bit (configurable) temperature readings which indicate the temperature of the device. It communicates over a 1-Wire bus that by definition requires only one data line (and ground) for communication with a central microprocessor. In addition it can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply.

The core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively. The default resolution at power-up is 12-bit.

Each and every DS18B20 has particular device address in HEX format like { 0x28, 0x1D, 0x39, 0x31, 0x2, 0x0, 0x0, 0xF0 }. So the program is designed on the basis of reading temperature from particular device address. So first the microcontroller scans the number of sensors. Let us assume 3 sensors are connected here. So it will just displays values of 3 different reading. If more sensors are connected, the reading will switch to multiple values. The value of temperature read by each sensors is displayed after interval of 2 seconds as Sensor Number 1 Temperature, Sensor Number 2 Temperature and upto the value of number of sensor connected.

To learn more about the code you can go through the video below. Or simply read the code as I have commented each and every thing about each line in code.



Video Tutorial & Explanation:

Recommended For You

About the Author: Alex Newton

Ask A Question .......

Close