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Arduino based digital thermometer

Once again, we come with a new project that is Arduino based digital thermometer. So we are in very first step forward toward analogue sensor interfacing with Arduino. Thermometer basically is a temperature measuring instrument. By using this we create very simple and interesting Arduino project that is “arduino based digital thermometer”. It can measure the atmospheric temperature very accurately. This atmospheric temperature may use as an input of lots of advanced projects.

Now question is how we measure?

We can measure the temperature in different way. It may work in principal of like thermal expansion of solids or liquids, pressure of gas, measurement of infrared energy etc. But in this project we use LM35 IC as a temperature sensor.

   I think, we all are know the roll of thermometer in our daily life.Thermometer use in wide field. It is use in weather forecasting, medicinal field, research center, maintaining storage temperature and lots of area. For temperature measuring, different thermometer are used in different field. Like mercury and glass thermometer is used in human body temperature sensing and other clinical use. But our project arduino based digital thermometer is used in measuring atmospheric room temperature.

Hardware required for arduino based digital thermometer:

The main concern of every one to makes a project is hardware of that. Is it readily available in market or not? How much cost of that? Therefore i give you list of hardware which are needed to make our project. And all the component readily available in online as well as local market. To make our simple project Arduino based digital thermometer, we need only

1) Arduino Uno Board

2) LCD LM016L 16*2 display

3) LM 35 (temperature sensor)

Project description:

Lets start with our project. But before entering in our project description, we should learn about LM-35 IC. Because it use as a temperature sensor in our project.

Something about LM-35:

arduino based digital thermometer

The LM35 series are precision integrated-circuit temperature devices with an output voltage in early proportional to the Centigrade temperature. This device has an advantage over linear temperature sensors calibrated in Kelvin. However as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling.

Firstly, it does not require any external calibration or trimming.

Secondly, it provide typical accuracy of ±¼°C at room temperature and ±¾°C over a full −55°C to 150°C temperature range.

Thirdly, lower cost is assured by trimming and calibration at the wafer level.

Fourthly, it has a very wide 4-V to 30-V power supply voltage range, which makes it ideal for many applications.

Fifthly and Finally, it is easily applied in the same way as other integrated-circuit temperature sensors. Glue or cement the device to a surface and the temperature should be within about 0.01°C of the surface temperature.

In conclusion, it is very handy component for making a projects.Never the less the low price and accuracy reading make it popular in making projects.

Again we come to main path of the project description. So first we see the connection diagram. In A0 pin of Arduino board we connect LM-35. For instance, we used pin numbers 12,11,5,4,3,2 for interfacing LCD. as we know LM35 is sensing temperature changes and convert it to proportional voltage label. This voltage is further process by arduino and display the temperature. Have a look on that, we used some simple calculation to convert LM-35 processed voltage to appropriate temperature. We used formula in programming like



Above all, means that the sensor value store in temp_reading variable. And further processed by temp_reading*(5.0/1023.0)*100 and store the result at variable temperature. Finally, value store in temperature variable is display in LCD. In bellow see the circuit diagram of Arduino based digital thermometer.

arduino based digital thermometer

Another essential thing to making Arduino protects is embedded C programming. Here i write the Embedded C code for our project Arduino based digital thermometer for your reference.

Embedded C Code
// Name : arduino based digital thermometer
// Author : Subham Dutta
// Date : 11-03-18
// Website :
#include LiquidCrystal lcd(12,11,5,4,3,2);
const int Sensor = A0;
byte degree_symbol[8] =
};void setup()
pinMode(Sensor, INPUT);
lcd.createChar(1, degree_symbol);
lcd.print(” NBCAFE Digital “);
lcd.print(” Thermometer “);
void loop()
{float temp_reading=analogRead(Sensor);
float temperature=temp_reading*(5.0/1023.0)*100;
lcd.print(“Temperature in C”);

When i made that project i made a simulation video. here i attach that . Which can help to build the project. So before start creating project, must go through the video.

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Subham Dutta

Subham Dutta

Hi myself Subham Dutta, having 15+ years experience in filed of Engineering. I love to teach and try to build foundation of students. Try to make them imagine what they learn.

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