Digital Thermometer using 8051 Microcontroller: Electronics Mini Project

Today we are going to make a simple mini-project using 8051 microcontrollers. A digital thermometer using 8051 microcontrollers. A thermometer is a device that measures temperature or temperature gradient using a variety of different principles. Let us see how to make Digital Thermometer using 8051 microcontrollers.

Components required

  • 8051 microcontroller (like AT89c51, 89C51RD2, etc.)

  • ADC0804

  • LM35 temperature sensor

  • Resistors, Potentiometer, etc.

Circuit diagram

[caption id="" align="aligncenter" width="490"]Digital Thermometer using 8051 Microcontroller Digital Thermometer using 8051 Microcontroller[/caption]

Working of Digital Thermometer

The output of digital thermometer is in Celsius scale. To display the output i.e. the temperature we have used a 16*2 LCD display. LM 35 is temperature sensor IC which is used to sense the temperature. Normally LM35 generates a 10mV change in output voltage per degree celsius change in temperature. This temperature is then converted into Celcius scale using analog to digital converter i.e. ADC0804.

LM 35 Temperature sensor:

[caption id="" align="aligncenter" width="130"]LM 35 Pin diagram LM 35 Pin diagram[/caption]

Specifications of LM 35 temperature sensor IC are as follows

  • The accuracy of LM35 is +-0.5 degree celsius.

  • Its temperature range is from -55 to 150-degree celsius.

  • Sensor gain = 10 (mV/Deg C)

  • Output impedance = 0.4 Ohm

  • Supply Voltage (Min) = 4V

  • Supply voltage (Max) = 30V

Applications of Digital Thermometer

  1. Thermometers are used in a wide variety of scientific and engineering applications, especially measurement systems.

  2. Digital thermometers can be used in roadways in cold weather climates to check if icing condition exists or not.


Click here to download C program and Proteus simulation files.

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