This document describes the design and implementation of a digital thermometer that measures atmospheric temperature using an LM35 temperature sensor and displays the results on an LCD screen. A PIC microcontroller reads the analog voltage from the LM35 sensor and converts it to a digital temperature reading. The microcontroller interfaces with the LCD to display the temperature. The project aims to create a simple, low-cost device for temperature measurement with applications in various industrial and agricultural settings.

1. DIGITAL THERMOMETERDIGITAL THERMOMETER

2. GROUP MEMBERSGROUP MEMBERS
●
SHYAMKUMAR V.SSHYAMKUMAR V.S
●
VISHNU SUNILKUMARVISHNU SUNILKUMAR
●
VINEETH V.HVINEETH V.H
●
VISHNU BABUVISHNU BABU
●
MOHAMMAD AKBARMOHAMMAD AKBAR

3. INTRODUCTION
In this project we are presenting a digital
thermometer for measuring the atmospheric
temperature.
LM35 is the temperature sensor used and the
measured value is displayed in LCD by interfacing
it with PIC microcontroller.

4. DESIGN AND IMPLEMENTAION

5. COMPONENTS USED
LM35 temperature sensor.
PIC 16F877A.
16x2 LCD.
Voltage regulator.
Crystal oscillator.
Resistors
Capacitors
Switch

6. CIRCUIT DIAGRAM

7. COMPONENT DESCRIPTIONCOMPONENT DESCRIPTION

8. TEMPERATURE SENSOR
LM 35
● Calibrated directly in ˚ Celsius.
● Linear + 10.0 mV/˚C scale factor.
● 0.5˚C accuracy guaranteeable (at
+25˚C)
● Rated for full −55˚ to +150˚C range.
● Suitable for remote applications.
● Operates from 4 to 30 volts.
● Less than 60 µA current drain.
● Low self-heating, 0.08˚C in still air.

9. CHARACTERISTICS OF LM 35

10. VOLTAGE REGULATOR
IC 7805
IC 7805 is a 5V Voltage Regulator that restricts voltage output to 5V.
Maximum input voltage is 35V.
Optimal input voltage is 7.2V.

11. PIC 16F877APIC 16F877A
Pin out diagram

12. FEATURES OF PIC 16F877AFEATURES OF PIC 16F877A

13. HIGH PERFOMANCE RISC CPU
●Operating speed:20MHz,200ns instruction cycle.
●Operating voltage:4v - 5.5 v
●15 interrupt sources.
●35 single word instructions

14. SPECIAL MICROCONTROLLERSPECIAL MICROCONTROLLER
FEATURESFEATURES
●Flash memory:14.3 KB(8192 words)
●Data SRAM :368 bytes
●Data EEPROM 256 bytes

15. PERIPHERAL FEATURESPERIPHERAL FEATURES
●33 I/O pins: 5 I/O ports
●USART/SCI with 9 bit address detection
●Timer 0 :8 bit timer/counter with 8 bit prescaler
●Timer 1 :16 bit timer/counter with prescaler
●Timer 2 :8 bit timer/counter with 8 bit period
register,prescaler and postscaler

16. ANALOG FEATURESANALOG FEATURES
●10 bit,8 channel A/D convertor
●Brown out reset
●Analog comparable module

17. INTERFACING OF PIC 16F877A
AND 16x2 LCD

19. PROGRAMPROGRAM

20. PORTA=0;
TRISA=0X01;
PORTB=0;
TRISB=0;

21. HOW IT WORKS...?HOW IT WORKS...?

22. ●The regulated 5V dc supply is given to the
PIC using 7805 voltage regulator.
●The temperature sensor LM35 produces an
analog voltage corresponding to the
temperature sensed by it.
●The analog voltage is converted into digital
form by the PIC 16F877A.
●The digital output is displayed on 16x2 LCD
by interfacing it with PIC 16F877A.
●The digital output is the required
temperature in degree celsius.

23. CIRCUIT SIMULATION USING PROTEUS

24. APPLICATIONSAPPLICATIONS
●Speed control of fan.
●Industrial applications.
●Applications in amplifiers.
●Laptop cooling.
●Application in farm.

25. CONCLUSIONCONCLUSION
In summary, the micro controller based thermometer is aIn summary, the micro controller based thermometer is a
device that measures the current atmospheric temperature. Itdevice that measures the current atmospheric temperature. It
has been successfully demonstrated that, this will serve as ahas been successfully demonstrated that, this will serve as a
device for finding out the temperature and displays it on LCD.device for finding out the temperature and displays it on LCD.
In this world of global warming the temperatureIn this world of global warming the temperature
measurement has an inevitable role, hence conclusion is mademeasurement has an inevitable role, hence conclusion is made
that this is a successful undertaking.that this is a successful undertaking.

26. ReferencesReferences
●Mazidi and Mazidi-8051,PIC & Embedded system
using assembly language programming
●www.electronics-project-design.com

27. ACKNOWLEDGEMENTACKNOWLEDGEMENT
We extend our heartfelt gratitude to Miss.We extend our heartfelt gratitude to Miss.
Remyamol and Miss. Binu for their valuableRemyamol and Miss. Binu for their valuable
guidance in our project.guidance in our project.

28. THANK YOUTHANK YOU