Raspberry Pi DS18B20 Tutorial | Basic Interface and IoT Monitor

In the previous DS18B20 Digital Sensor Project, we have seen how to interface Arduino with DS18B20 and display the temperature on a 16X2 LCD Display. In this project, we will learn about the Raspberry Pi DS18B20 Temperature Sensor interface and also how to monitor the temperature from a remote location i.e. web based temperature monitor.

The project consists of two parts: the first part includes interfacing DS18B20 with Raspberry Pi and viewing the temperatures on the terminal and in the second part, accessing the Raspberry over the internet using Dataplicity and viewing the temperatures from a remote computer.

Raspberry Pi DS18B20 Temperature Sensor Image 1
Raspberry Pi DS18B20 Temperature Sensor Image 2


We have already seen about the DS18B20 Temperature Sensor in the previous tutorial. But as a reminder, I’ll mention a few important details about the sensor.

DS18B20 is a Digital Temperature Sensor that communicates over 1-Wire Interface. Since Raspberry Pi doesn’t have any Analog Input Pins, choosing a Digital Sensor for implementation in projects makes it obvious.

Arduino DS18B20 Temperature Sensor

The DS18B20 Sensor in its TO-92 package has three pins: GND, DQ (Data) and VDD. You can power the sensor either through VDD Pin or the sensor can draw power from DQ Pin (parasite power mode).

For more information on the DS18B20 Temperature Sensor and how to interface it with Arduino, visit: Arduino DS18B20 Interface Tutorial

Circuit Diagram of Raspberry Pi DS18B20 Interface

The following image shows the circuit diagram of interfacing DS18B20 Temperature Sensor with Raspberry Pi. The first image shows the connections between Raspberry Pi and DS18B20 using Fritzing Parts.

Raspberry Pi DS18B20 Temperature Sensor Fritzing

If you want a clear understanding of the connections, the following wiring diagram might be helpful.

Raspberry Pi DS18B20 Temperature Sensor Wiring

Components Required

  • Raspberry Pi 3 Model B
  • DS18B20 Digital Temperature Sensor
  • 4.7KΩ Resistor (1/4 Watt)
  • Breadboard
  • Connecting Wires
  • Micro USB Cable
  • Computer with Internet Connectivity

Circuit Design

First, connect the VDD and GND Pins of DS18B20 Sensor to 3.3V and GND Pins of Raspberry Pi. DS18B20 can tolerate +5V Supply.

Then connect a 4.7KΩ Resistor between the DQ pin of DS18B20 and 3.3V i.e. a pull-up resistor. Finally, connect the DQ Pin to GPIO4 (i.e. Physical pin 7) of Raspberry Pi.

Raspberry Pi DS18B20 Temperature Sensor Interface

We will now see how to interface DS18B20 Temperature Sensor and Raspberry Pi. Using this interface, you can develop applications like Weather Station, Remote Temperature Monitor, Temperature Data Logger etc.

Enable 1-Wire Interface in Raspberry Pi

Make the connections as per the circuit diagram and power on the Raspberry Pi. Since DS18B20 Sensor communicates only on 1-Wire Interface, we need to enable the same on Raspberry Pi. So, open Raspberry Pi’s Command Prompt and open the config.txt file by entering the following command.

sudo nano /boot/config.txt

Raspberry Pi DS18B20 Temperature Sensor Image 3

At the end of this file, add the following statement.


Save the config.txt file by pressing Ctrl+x and then y. After saving the file, you need to reboot the Raspberry Pi. So, use the following command to reboot your Raspberry Pi.

sudo reboot

Check whether the Sensor is Working

The following steps will be useful if you want to check whether your DS18B20 Temperature Sensor is working or not. You can skip this step and proceed with writing the Python Program for Raspberry Pi.

After your Raspberry Pi has rebooted, login to Raspberry Pi and in the command prompt, enter the following commands.

sudo modprobe w1-gpio
sudo modprobe w1-therm

NOTE: You can also enter them in a single line by typing sudo modprobe w1-gpio && sudo modprobe w1-therm in the command prompt.

Now, you need to change to the devices directory using the following command.

cd /sys/bus/w1/devices

In this directory, look for list of devices by using the ls command.

In my case, the directory corresponding to DS18B20 Sensor is 28-0316555c2fff. Open this directory by using the cd command.

cd 28-0316555c2fff

NOTE: Replace 28-0316555c2fff with the name appeared in your directory.

To view the raw temperature reading from the sensor, use the following command.

cat w1_slave

If you notice, the value t=25250 at the end of the second line of the result represents the temperature as 25.25 0C.

Raspberry Pi DS18B20 Temperature Sensor Image 4

Python Program for Reading Temperature from DS18B20

I’ve created a folder called ‘projects’ in Raspberry Pi’s Home. Change to this directory and create a new Python file with name ‘temperature.py’ using vim editor.

sudo vim python temperature.py

Raspberry Pi DS18B20 Temperature Sensor Image 5

In this file, type the following code and save the file.

After writing or copying the code in to editor, save the file and you are ready to run the script. To run the Python Script, simply use the following command.

sudo python temperature.py

Raspberry Pi DS18B20 Temperature Sensor Image 6

You will get the temperature in Degree Celsius. If you want to display the temperature in Fahrenheit, simply modify the code in the def read_temp(): section.

IoT based Temperature Monitor

We will take the project a step ahead by setting up a Web based Monitor of Temperature. For this purpose, I’ll be using the services of Dataplicity. Go to the home page Dataplicity from the link provided.

Enter your email id in the section 1 and click on Start. A Code will appear in the Section 2. Copy this code and paste it in the Command Prompt (Terminal) of the Raspberry Pi to activate the remote shell.

Raspberry Pi DS18B20 Temperature Sensor Image 7

The code will be something like this.

curl https://www.dataplicity.com/xxxxxxxx.py | sudo python

NOTE: ‘xxxxxxxx’ will be specific to your email id.

After entering the code, it will try to download the necessary file on to your Raspberry Pi, registers your device with the Dataplicity Server, configures your system and finally runs the remote agent.

Raspberry Pi DS18B20 Temperature Sensor Image 8

Now, click on “Done” in the Dataplicity website to begin remote access of your Raspberry Pi. The terminal will be enable and you can login using your Raspberry Pi’s credentials.

As my Python Script for DS18B20 Sensor is stored in the folder ‘projects’, I’ll move to that directory and run the script using the following command.

sudo python temperature.py

Raspberry Pi DS18B20 Temperature Sensor Image 9

That’s it. You have successfully completed your IoT based Temperature Monitor Application using Raspberry Pi, DS18B20 Temperature Sensor and Dataplicity.

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