The temperature can be measured using different principle like the thermal expansion of solids or liquids, pressure of gas, measurement of infrared energy etc. with the help of a device named thermometer. The construction and functioning of thermometer might change depending on the principle used, but ultimately it ends up measuring the temperature.
Temperature measurement is a vital step in various application, whether it is used in industries, weather studies, medicinal field or scientific research. Among different forms of thermometer available in the market, this tutorial by electronics hub is focused on the design of Arduino-based digital thermometer for monitoring the room temperature.
This digital thermometer can be converted into a portable device, when powered by a 9V battery and can be easily transported between different rooms or locations. It can also be used in transportation vehicles to determine the icing conditions of the road. The system like air conditioning, heating and cooling can be controlled, based on the reading of the temperature, either manually or automatically.
Through this project, the room temperature can be monitored within the range of -550C to +1500C with very accurate readings.The Hardware required for the project includes Arduino Uno, LM35 Temperature Sensor, and 16X2 LCD Display. The LM35 is used in the circuit design of digital thermometer as the temperature sensor in analog form and therefore pin 2 that act as the output of LM35, is coupled with analog input A0 of Arduino.
LM35 is an accurate centigrade temperature sensor, whose sensor output voltage is directly proportional to the temperature in centigrade and is used in the array of -550C to +1500C with +/- 0.750C accuracy. LM34 also offer equivalent centigrade temperature sensor and is used to measure temperature in Fahrenheit. If the temperature is required in Fahrenheit, the code can be simply modified for converting Centigrade to Fahrenheit.
The analog values are converted to digital and the result are displayed on the LCD and its pin 1 and 2 are connected to ground and supply respectively. The contrast of the display is controlled by Pin 3 of LCD, which is connected to the wiper of a 10 KΩ POT while Pin 15 and 16 of LCD are used for the backlight of the LCD.
The working of this high precision digital thermometer is based on the circuit. To begin with, LM35 is responsible for monitoring the room temperature continuously and to provide an analog corresponding voltage which is directly proportional to the temperature.
This analog data, captured from LM35 is transferred to Arduino through A0. The Arduino translates the analog voltage value into digital temperature readings by using the written code and display the value on the LCD. The code can be programmed according to the rate of change of captured temperature, which provides an accurate reading of room temperature on LCD. For codes and other details, visit the link below.
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