25-04-2012, 11:09 AM
Temperature Controlled DC Fan using PIC18F452 Microcontroller
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INTRODUCTION
In today’s hi-tech world computers have become part and partial of life. But temperature of the
processor inside the computing system needs to be controlled for proper functioning of the
semiconductor devices. Thus it is important to keep the temperature within the prescribed
limits.
Why use microcontroller?
To control the temperature it must be sensed and check in what range it lies according to which
the speed of the cooling fan is decided. These tasks can be performed very easily using a
microcontroller. It involves decision making steps, which can be easily achieved by using a
microcontroller instead of complex IC circuits.
Methodology
First of all the temperature will be sensed by a temperature sensor, which works as a
transducer and gives voltage equivalent of the sensed temperature. This analog signal will
be fed to the ADC of PIC microcontroller. Thereafter the adc will take the analog input and
convert it to digital domain. Now the digital data will be compared to the prespecified
conditions in the program. According to result of comparison, desired duty ratio will be
generated.
Project Objective
This project targets on designing, simulating, prototyping and testing of a temperature
controlled dc motor fan that is practically used for cooling the processor in computers.
The primary aim of our project is to control dc motor, fan in our project, using a pic micro
controller. The fan will be given an input duty ratio which increases in steps of 25% for
every 10 degree rise in temperature, starting from 25 degrees. The fan will be kept off for
temperature less than 25 degree and will run maximum speed for temperature above 55
degrees.
Components and Hardware
For controlling the temperature we need
values and types of components pre designed and the pic configured. So to start with
the circuit will be very complicated understand. Thus a block diagram representation of
the circuit is presented.
Results and Conclusion
The prototype of the Temperature controlled DC fan using PIC18F452 microcontroller was simulated
and fabricated. The sensor was successfully interfaced with the microcontroller using ADC the
desired output pulses were observed in the simulation using PROTEUS software.