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temperature controlled fan using 8051

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vaibhav aggarwal

on 4 September 2013

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Transcript of temperature controlled fan using 8051

Temperature Controlled Fan
Hardware tools
Temperature Controlled Fan
The project is an implementation of an embedded system which is used to change the speed of a rotating fan depending upon the readings of a temperature sensor.
It involves using the 8051 Microcontroller, which will control the functions requirements of the system.
An Analog to Digital Converter (ADC) is required which would convert the analog signals provided by the temperature sensor into digital form for compatibility with the microcontroller.
Microcontroller At89C51
Temperature sensor IC LM35
7-segment LED display
Power Supply
At89C51 is a 8-bit microcontroller that belongs to INTEL's 8051 family.
It has
16 bits of address
128 bytes of RAM
Two 16 bit bytes of ROM
It has got wide variety of instructions like data transfer, arithmetic and logical instructions.
It also has features of branch instruction, serial communication, timer feature and ISR execution.
The LM35 series are precision IC temperature sensor whose output is linearly proportional to Celsius scale.

The LM35 does not require any external calibration to provide accuracies of +-1/4 degree centigrade to +-3/4 degree centigrade over -55 to +150 degree centigrade.
The ADC0808 is a monolithic CMOS device with an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor compatible control logic.
The converter features a high impedance chopper stabilized comparator, a 256R voltage divider with analog switch tree and a successive approximation register.
7-Segement display
It is a form of electronic display device for displaying decimal numericals.
These are widely used in digital clocks, electronic meters and other electronic devices for displaying numerical information.
Speed of fan is monitored by temperature variation.
Basic idea behind the project is getting the temperature, displaying the temperature and change in the temperature is reflected as change in the speed of the fan.
We use LM35 temperature sensor whose output is given to ADC.
The entire working is enabled or disabled by external interrupt.
The interrupt signal is generated by opamp sensor, which can be calibrated for different types of sensor.
The output of ADC is used to select unique values of temperature from look up table in program.

Based on different output values of ADC, different 2 digits value for temperature representation are selected, which in turn are provided to display port.
Display port includes 7-segment display devices where digits are displayed using some special HEX code.
For speed variation we have used PWM concept which in turn stands by duty cycle variation.
This varying speed controls the running motion of DC motor.
Block Diagram
Circuit Diagram
It can be used everywhere where power consumption has to be controlled.
In home appliances, at institutes, firms, organizations, industries.
In computers, it can be used to cool the processor. As it gets heated, the speead of the fan can be made proportional to the temperature rise and fall.
Presented by-
Vaibhav Aggarwal (11BCE0372)
Rajan Gupta (11BCE0169)
Digvijayraj Parmar (11BCE0369)
Full transcript