Room Temperature Monitoring System using LM35 Temperature Sensor and Arduino

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Hello friends! Welcome back to ElectroDuino. This blog is base on Room Temperature Monitoring System using LM35 Temperature Sensor and Arduino. Here we will discuss Introduction to Room temperature monitoring system, Project Concept, Block Diagram, Components Required, Circuit Diagram, Working Principle, and Arduino code.


In this project, we will learn how to make a Room temperature monitoring system using LM35 Temperature Sensor and Arduino. This system can measure room temperature continuously and show the value on a Display. The LM35 is a 3- terminal Temperature Sensor IC that can be used to sense ambient and surface temperatures. It can measure temperature in the range of -55°C to 150°C. This sensor provides an analog output voltage that proportional to the temperature.  So, it is a perfect sensor to measure Room temperature. Here we will build a very small and portable Temperature Monitoring System/Device. It can be easily used in offices, schools, buildings, and industries to measure temperature.

Project Concept

This is a very simple project, 3 key components are needed to build it, these are LM35 Temperature Sensor, Arduino Board, and OLED Display Module. The LM35 sensor measures the temperature around it and produces output voltage. The Arduino Board is the main microcontroller, it controls the whole system. Here we will use Arduino Nano, you can use other types of Arduino Board like Arduino Uno, Mega, etc. It will read output data from the Sensor and calculate the temperature value using this output data. Then it sends the Temperature value to the OLED Display. We will see this value on the Display.

Block Diagram of Room Temperature Monitoring System

Room temperature monitoring system/Device using LM35 Temperature Sensor and Arduino Block Diagram
Room temperature monitoring system Block Diagram

Components Required 

Components NameQuantity
Arduino Nano1
LM35 Temperature Gas Sensor1
0.96 inch I2C OLED display1
Slide Switch1
9V Battery with Battery connector1
PCB Zero board1
Connecting wiresAs required in the circuit diagram


Tools Required

Tools NameQuantity
Soldering Iron1
Soldering wire1
Soldering flux1
Soldering stand1
Desoldering pump1

Required Library

We need to add 2 libraries in Arduino IDE software. These are:

  • Download the Adafruit_GFX.h library here: CLICK
  • Download the Adafruit_SSD1306.h library here: CLICK

Circuit Diagram of Room Temperature Monitoring System using LM35 Temperature Sensor

Room temperature monitoring system/Device using LM35 Temperature Sensor and Arduino Circuit Diagram
Room Temperature Monitoring System using LM35 Circuit Diagram

Working Principle of Room Temperature Monitoring System

The LM35 is an analog Temperature Sensor. Its output voltage is directly proportional to the temperature. The output voltage will be a rise of 10mV (0.01V) for every 1°C rise in temperature. In this project, the LM35 Sensor Output Pin is connected to the Analog Pin “A3” of the Arduino Nano.  The Arduino Nano has an in-built 10 bit ADC (analog-to-digital converter), which converts the analog output of LM35 to digital output form (0-1024 bits).

After read the Data from the output pin of LM35, Arduino calculates the Temperature using some simple formulas. These formulas are used in Arduino Code/Programing.

First of all, Arduino calculate the temperature in Degree Celsius format. The formula is:

Temperature(C) = ((analogRead * 5.0)/1024)*100.0  Degree Celsius

We also want to print the Temperature Value in Fahrenheit format. So, we also add another formula in the Arduino code/Programming, which converts the temperature value Celsius to Fahrenheit. The formula is:

Temperature (F) = {(C *1.8) +32} Fahrenheit

Where C is the temperature value in Degree Celsius.

 After the Temperature Calculation the Arduino print this Value on OLED Display Module. 

Arduino Code


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