Temperature Controlled Fan

Temperature controlled fan with display
AIET/ECE/PR/01

CHAPTER 1
INTRODUCTION AND LAYOUT

1.0ABOUT THE PROJECT
Temperature controller can be done by using Electronic circuit, Microprocessor or
microcontroller. Now microcontroller is advanced among all above circuits therefore we are
using Microcontroller for temperature controlling.
In this project, microcontroller 89s51 forms the processing part, which firstly receives data
from ADC. ADC receives data from temperature sensor through amplifier. Then
microcontroller 89s51 performs the comparison of current temperature and set temperature as
per the logic of program for which microcontroller has already been programmed. The result
obtained from the above operation is given through output port of 89s51 to LCD display of
relevant data and generated pulses as per the logic program which is further fed to the driver
circuit to obtain the desired output of ceiling fan.


AIET/ECE/PR/02

FIG 1.0 System block diagram
1.1 Description of components used:
-1.1.1 Temperature sensor: - its a transducer. It converts temperature into equivalent
electrical signal. Its output voltage increases linearly with increase in temperature. So by
measuring the output voltage we may observe increase or decrease in temperature
1.1.2 ADC: because the output of sensor is an analog form, it must be converted into
equivalent digital form before it is given to micro-controller. So, 8-bit ADC converts analog
signal from sensor into 8-bit digital signal that is given to micro-controller.
1.1.3 Micro-controller: - It performs following tasks
Controls ADC and reads digital value at periodic interval
Generates PWM and controls speed of DC fan through DC driver
Indicates current speed on LED bar graph display.
1.1.4 LED bar graph: - its 5-step bar graph that displays min speed as one LED ON and max
speed as all five LEDs ON.

AIET/ECE/PR/03

1.1.5 DC Driver: - the direct micro-controller output is not able to drive DC motor. So the DC
driver will take input PWM signal from micro-controller and generates enough current to drive
DC motor through this PWM.
1.2 Designing the layout
DIPTRACE is EDA software for creating schematic diagrams and printed circuit boards.
The first version of DipTrace was released in August, 2004. The latest version as of March
2013 is DipTrace version 2.3.1. The interface and tutorials are multi-lingual (currently
English, Czech, Russian and Turkish).
[2]
In January of 2011, Parallax switched from Eagle
to DipTrace for developing its printed circuit boards.

Fig 1.1 Layout on PCB Wizard

1.3Printed circuit board (PCB)

AIET/ECE/PR/04

A printed circuit board (PCB) mechanically supports and electrically connects electronic
components using conductive tracks, pads and other features etched from copper
sheets laminated onto a non-conductive substrate. PCB's can be single sided (one copper
layer), double sided (two copper layers) or multi-layer. Conductors on different layers are
connected with plated-through holes called vias. Advanced PCB's may contain components -
capacitors, resistors or active devices - embedded in the substrate.
Printed circuit boards are used in all but the simplest electronic products. Alternatives to PCBs
include wire wrap and point-to-point construction. PCBs are more costly to design but allow
automated manufacturing and assembly. Products are then faster and cheaper to manufacture,
and potentially more reliable.
Much of the electronics industry's PCB design, assembly, and quality control follows standards
published by the IPC organization.
When the board has only copper connections and no embedded components it is more correctly
called a printed wiring board (PWB) or etched wiring board. Although more accurate, the term
printed wiring board has fallen into disuse. A PCB populated with electronic components is
called a printed circuit assembly (PCA), printed circuit board assembly or PCB
assembly (PCBA). The IPC preferred term for assembled boards is circuit card
assembly (CCA),
[1]
for assembled backplanes it is backplane assemblies. The term PCB is used
informally both for bare and assembled boards.
1.4 Steps followed during fabrication
1.4.1Patterning
In subtractive methods the unwanted copper is removed to leave only the desired copper
pattern. In additive methods the pattern is electroplated onto a bare substrate using a complex
process. The advantage of the additive method is that less material is needed and less waste is
produced. The pattern in the manufacturer's PCB CAM system is usually output on a
photomask (photo-tool, film) by a photo plotter and replicated via silk screen printing or by
exposing on a photo-sensitive photoresist coating. Direct laser imaging techniques are
sometimes used for high-resolution requirements.
1.4.2Subtractive methods

AIET/ECE/PR/05

This method id used to remove copper from an entirely copper-coated board:
Silk screen printing: Uses etch-resistant inks to protect the copper foil. Subsequent etching
removes the unwanted copper. Alternatively, the ink may be conductive, printed on a blank
(non-conductive) board. The latter technique is also used in the manufacture of hybrid circuits.
Photoengraving: Uses a photomask and developer to selectively remove a photoresist coating.
The remaining photoresist protects the copper foil. Subsequent etching removes the unwanted
copper.
PCB milling: Uses a two or three-axis mechanical milling system to mill away the copper foil
from the substrate. A PCB milling machine (referred to as a 'PCB Prototyper') operates in a
similar way to a plotter, receiving commands from the host software that control the position of
the milling head in the x, y, and (if relevant) z axis. Data to drive the Prototyper is extracted
from files generated in PCB design software and stored in HPGL orGerber file format.
1.5Chemical etching
Chemical etching is usually done with ammonium persulfate or ferric chloride. For PTH
(plated-through holes), additional steps of electroless deposition are done after the holes are
drilled, then copper is electroplated to build up the thickness, the boards are screened, and
plated with tin/lead. The tin/lead becomes the resist leaving the bare copper to be etched away.
As more copper is consumed from the boards, the etchant becomes saturated and less effective;
different etchants have different capacities for copper, with some as high as 150 grams of
copper per litre of solution. In commercial use, etchants can be regenerated to restore their
activity, and the dissolved copper recovered and sold. Small-scale etching requires attention to
disposal of used etchant, which is corrosive and toxic due to its metal content.
The etchant removes copper on all surfaces exposed by the resist. "Undercut" occurs when
etchant attacks the thin edge of copper under the resist; this can reduce conductor widths and
cause open-circuits. Careful control of etch time is required to prevent undercut. Where
metallic plating is used as a resist, it can "overhang" which can cause short-circuits between
adjacent traces when closely spaced. Overhang can be removed by wire-brushing the board
after etching

AIET/ECE/PR/06

1.6Drilling
Holes through a PCB are typically drilled with small-diameter drill bits made of solid
coated tungsten carbide. Coated tungsten carbide is recommended since many board materials
are very abrasive and drilling must be high RPM and high feed to be cost effective. Drill bits
must also remain sharp so as not to mar or tear the traces. Drilling with high-speed-steel is
simply not feasible since the drill bits will dull quickly and thus tear the copper and ruin the
boards. The drilling is performed by automated drilling machines with placement controlled by
a drill tape or drill file. These computer-generated files are also called numerically controlled
drill (NCD) files or "Excellon files". The drill file describes the location and size of each drilled
hole. These holes are often filled with annular rings (hollow rivets) to create vias. Vias allow
the electrical and thermal connection of conductors on opposite sides of the PCB..
It is also possible with controlled-depth drilling, laser drilling, or by pre-drilling the individual
sheets of the PCB before lamination, to produce holes that connect only some of the copper
layers, rather than passing through the entire board. These holes are called blind vias when they
connect an internal copper layer to an outer layer, or buried vias when they connect two or
more internal copper layers and no outer layer.

AIET/ECE/PR/07

Fig 1.2 Flow chart for pcb fabrication steps


AIET/ECE/PR/08

CHAPTER 2
CIRCUIT AND CONNECTIONS

2.0Complete circuit: -

Fig 2.0 Complete circuit diagram

I have divided complete circuit in three different sections
1. ADC section
2. Controller section
3. DC driver section

2.1ADC Section: -


AIET/ECE/PR/09

Fig 2.1 ADC Section

2.2 About LM35
It is semiconductor type temperature sensor. Here are its main features
1. Calibrated directly in Celsius (Centigrade)
2. Linear + 10.0 mV/C scale factor
3. 0.5C accuracy guaranteed (at +25C)
4. Rated for full ?55 to +150C range
5. Operates from 4 to 30 volts
6. Less than 60 ?A current drain
7. Low self-heating, 0.08C in still air
8. Nonlinearity only 1?4C typical
9. Low impedance output, 0.1 W for 1 mA load
So its output changes to 10 mV with change in 1
o
C. I have set the reference voltage (Vref)
of ADC to 2.56 V. so its full scale input voltage will be 5.12 V. and resolution will be
ADC resolution = FSV / (2
8
- 1)
= 5.12 / 256
= 0.02
= 20 mV
From above calculation we can say that for every 2
o
C change in temperature, the ADC output
will change. So ADC output is perfectly calibrated to
o
C change in temperature. Its control
signals and data bus are interfaced with micro-controller. There are four control signals CS,
RD, WR, INTR, and 8-bit data bus.
8-bit data bus it is connected with port P1 of 89C52. It sends 8-bit digital data equivalent to
analog output form LM35.

AIET/ECE/PR/010

CS (chip select) active low input signal. Connected to ground permanently to always enable
chip.
RD (read enable) active low input signal. Connected with pin no 17 (P3.7) of 89C52
WR (write enable) active low input also known as start of conversion (SoC). Connected
with pin no 16 (P3.6) of 89C52
INTR (interrupt out) low output signal also know as end of conversion (EoC). Connected
with pin no 13 (P3.3 of 89C52) The LM35 series are precision integrated-circuit temperature
sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature.
The LM35 thus has an advantage over linear temperature sensors calibrated in Kelvin, as the
user is not required to subtract a large constant voltage from its output to obtain convenient
Centigrade scaling. The LM35 does not require any external calibration or trimming to provide
typical accuracies of C at room temperature and C over a full -55 to +150C
temperature range. Low cost is assured by trimming and calibration at the wafer level. The
LM35's low output impedance, linear output, and precise inherent calibration make interfacing
to readout or control circuitry especially easy. It can be used with single power supplies, or
with plus and minus supplies. As it draws only 60 A from its supply, it has very low self-
heating, less than 0.1C in still air. The LM35 is rated to operate over a -55 to +150C
temperature range, while the LM35C is rated for a -40 to +110C range (-10 with improved
accuracy). The LM35 series is available packaged in hermetic TO-46 transistor packages, while
the LM35C, LM35CA, and LM35D are also available in the plastic TO-92 transistor package.
The LM35D is also available in an 8-lead surface mount small outline package and a plastic
TO-220 package.
2.3 CONTROLLER AND DRIVER SECTION: -
The details of the circuit have been mentioned in the Circuit Diagram Tab.
Connections: -
The connections from previous sections (ADC) are shown. Five LEDs LED1 to LED5 are
connected to port2 pins P2.0 to P2.4 as shown. A 12 MHz crystal with two 33 pF capacitors is
connected to 89C52 crystal pins to provide clock signal. A capacitor C4 with diode D1 and
resistor R4 forms power on reset circuit. This completes controller section.


AIET/ECE/PR/011

In driver section, IC555 is configured in monostable mode that receives PWM from 89C52 as
trigger input and it generates exact inverted PWM. Its time constant is less than 0.1 ms that is
decided by R1C1. This PWM output is fed at the base of PNP type Darlington pair transistor
TIP127. The collector of TIP127 is connected to DC fan motor. It will provide enough current
to drive motor.

Operation: -
The micro-controller initially starts rotating motor at minimum speed by applying 30% duty
cycle.
Then periodically it will read the digital value of current temperature from ADC
If new value is higher than previous value then duty cycle is increased in 5 steps as 30%,
50%, 70%, 80% and 90%.
Similarly if new value is lower duty cycle is decreased in same steps.
If temperature remains constant the output duty cycle also remains constant and so does the
speed.
So this is continuous process. The micro-controller continuously reads new temperature value
and continuously varies speed of fan.
The program loaded into micro-controller is written in C language and compiled using keil
IDE. The code can be retrieved from the Code tab.
There are two functions and one main function.
Int1() is an interrupt function. It reads digital value given by ADC. Then it increases or
decreases duty cycle as per received value.
Delay() function generates variable delay in step of 1 ms. If value passed to it is 5 that means it
will generate delay of 5 ms and so on.


AIET/ECE/PR/012

Fig 2.2 Temperature based fan
AT89S8253 that is capable of taking decisions on the basis of input. Crystal oscillator is used
to generate frequency it is of 10MHz. This crystal is coupled with 22pf /33pf capacitor so that
microcontroller circuitry get complete and it can work with programming.
The complete working of this system can be divided in the following blocks for easier
understanding
2.2Temperature Sensor
It consists of the sensor which measures the temperature of its surrounding and communicates
that data to the microcontroller. The sensor used here is DS18B20.It is a highly sensitive
sensor with a resolution of less than 0.50C. It communicates with microcontroller using one
wire protocol of communication.
2.3Microcontroller Block
Microcontroller takes the temperature data from DS18B20 temperature sensor. Based on this
data it decides which device is to be operated and at what power it is to be operated. The
outputs of the microcontroller are fed into the power amplifying unit. It also controls the
display on the Display Unit. The microcontroller used in this project is AT89S8253.

AIET/ECE/PR/013

2.3 Display Unit
It is 16*2 LCD that shows the temperature of the room at any particular instant. It also shows
which appliance is being used and at what power it is being used.
2.4Power amplifying block
This is the block that converts the TTL outputs of microcontroller into high power signals.
These signals can then be used be used to drive appliances. This block consists of relays, relay
pre-amplifiers and transistors.

2.5Appliances Block
This block consists Fan and a DC motor whose status show the appliance used. This block is
connected to the Power Amplifying Block.
2.6Power supply Block
This consist a 12V AC to DC Adaptor and a power regulator (7805) to get 5v power supply.
This 12V supply drives power amplifiers and appliances while the 5v supply drives the sensor,
microcontroller and the LCD.
This project report contain full working, block diagram, component used in the project,
component description. Use this report only for your reference and study work.
2.7. ADC 0804 LCN
The ADC0801, ADC0802, ADC0803, ADC0804 and ADC0805 are CMOS 8-bit successive
approximation A/D converters that use a differential potentiometric ladder-similar to the 256R
products. These converters are designed to allow operation with the NSC800 and INS8080A
derivative control bus with TRI-STATE output latches directly driving the data bus. These
A/Ds appear like memory locations or I/O ports to the microprocessor and no interfacing logic
is needed.
Differential analog voltage inputs allow increasing the common-mode rejection and offsetting
the analog zero input voltage value. In addition, the voltage reference input can be adjusted to
allow encoding any smaller analog voltage span to the full 8 bits of resolution.

AIET/ECE/PR/014

2.8. Opt coupler
In electronics an opto-isolator, also called an optocoupler, photocoupler, or optical isolator, is
"an electronic device designed to transfer electrical signals by utilizing light waves to provide
coupling with electrical isolation between its input and output". The main purpose of an opto-
isolator is "to prevent high voltagesor rapidly changing voltages on one side of the circuit from
damaging components or distorting transmissions on the other side."Commercially available
opto-isolators withstand input-to-output voltages up to 10 kV and voltage transients with
speeds up to 10 kV.
2.9Voltage Regulator L7805
Voltage Regulator L7805 (regulator), usually having three legs, converts varying input voltage
and produces a constant regulated output voltage. They are available in a variety of outputs.
The most common part numbers start with the numbers 78 or 79 and finish with two digits
indicating the output voltage. The number 78 represents positive voltage and 79 negative one.
The 78XX series of voltage regulators are designed for positive input. And the 79XX series is
designed for negative input.

Fig 2.3 Voltage regulator
2.10. Crystal Oscillator 12MHz
An oscillator is something that produces an output that repeats regularly. In the electronics field
this will be an electrical waveform, often but not always a sine wave.The most important
property of an oscillator is its frequency: the rate at which the output repeats. This is measured
in Hertz (Hz for short). One Hertz is one repetition (aka cycle) per second. One Mega Hertz

AIET/ECE/PR/015

(MHz) is one million repetitions per second. One of the problems in designing a high quality
oscillator is maintaining the output frequency at the value required. One method is to control it
by a quartz crystal; this is cut so that it vibrates mechanically at the design frequency, and is
coupled to the electronics by the piezo-electric effect.A 12 MHz crystal oscillator is an
electronic circuit, whose output frequency is controlled by a quartz crystal to repeat 12 million
times per second.

Fig 2.4 Crystal oscillator

CHAPTER 3
DESCRIPTION OF COMPONENTS

3.1Resistors
Axial- lead resistors on tape. The tape is removed during assembly before the leads are formed
and the part is inserted into the board. Three carbon composition resistors in a 1960s valve
(vacuum tube) radio. A resistor is a two-terminal electronic component that produces a voltage
across its terminals that is proportional to the electric current through it in accordance with
Ohm's law:


AIET/ECE/PR/016

Fig 3.1 Variable resistor
Variable resistors consist of a resistance track with connections at both ends and a wiper which
moves along the track as you turn the spindle. The track may be made from carbon, cermets
(ceramic and metal mixture) or a coil of wire (for low resistances). The track is usually rotary
but straight track versions, usually called sliders, are also available.
Variable resistors may be used as a rheostat with two connections (the wiper and just one end
of the track) or as a potentiometer with all three connections in use. Miniature versions called
presets are made for setting up circuits which will not require further adjustment.
Variable resistors are often called potentiometers in books and catalogues. They are specified
by their maximum resistance, linear or logarithmic track, and their physical size
3.2 Capacitor
A capacitor or condenser is a passive electronic component consisting of a pair of conductors
separated by a dielectric. When a voltage potential difference exists between the conductors, an
electric field is present in the dielectric. This field stores energy and produces a mechanical
force between the plates. The effect is greatest between wide, flat, parallel, narrowly separated
conductors.
The conductors and leads introduce an equivalent series resistance and the dielectric has an
electric field strength limit resulting in a breakdown voltage.
Capacitors are widely used in electronic circuits to block the flow of direct current while
allowing alternating current to pass, to filter out interference, to smooth the output of power
supplies, and for many other purposes. They are used in resonant circuits in radio frequency
equipment to select particular frequencies from a signal with many frequencies.

AIET/ECE/PR/017

Ceramic Capacitor:
Ceramic capacitors are constructed with materials such as titanium acid barium used as the
dielectric. They can be used in high frequency applications. Typically, they are used in circuits
which bypass high frequency signals to ground.
These capacitors have the shape of a disk. Their capacitance is comparatively small.
The capacitor on the left is a 100pF capacitor with a diameter of about 3 mm.The capacitor on
the right side is printed with 103, so 10 x 10
3
pF becomes 0.01 F. The diameter of the disk is
about 6 mm.
Ceramic capacitors have no polarity Ceramic capacitors should not be used for analog circuits,
Because distort the signal
3.3LED
A light-emitting diode (LED) is an electronic light source. LEDs are used as indicator lamps in
many kinds of electronics and increasingly for lighting. LEDs work by the effect
of electroluminescence, discovered by accident in 1907. The LED was introduced as a practical
electronic component in 1962. All early devices emitted low-intensity red light, but modern
LEDs are available across the visible, ultraviolet and infra red wavelengths, with very high
brightness.
LEDs are based on the semiconductor diode. When the diode is forward biased.
LEDs present many advantages over traditional light sources including lower energy
consumption, longer lifetime, improved robustness, smaller size and faster switching. However,
they are relatively expensive and require more precise current and heat management than
traditional light sources.
Applications of LEDs are diverse. They are used as low-energy indicators but also for
replacements for traditional light sources in general lighting, automotive lighting and traffic
signals. The compact size of LEDs has allowed new text and video displays and sensors to be
developed, while their high switching rates are useful in communications technology
3.4 Relay
A relay is an electrical switch that opens and closes under the control of another electrical

AIET/ECE/PR/018

circuit. In the original form, the switch is operated by an electromagnet to open or close one
or many sets of contacts. It was invented by Joseph Henry in 1835. Because a relay is able to
control an output circuit of higher power than the input circuit, it can be considered to be.

Fig 3.1 Sugar cube relay
3.5 LCD
A liquid crystal display (LCD) is a thin, flat display device made up of any number of color or
monochrome pixels arrayed in front of a light source or reflector. Each pixel consists of a
column of liquid crystal molecules suspended between two transparent electrodes, and two
polarizing filters, the axes of polarity of which are perpendicular to each other. Without the
liquid crystals between them, light passing through one would be blocked by the other. The
liquid crystal twists the polarization of light entering one filter to allow it to pass through the
other.
Many microcontroller devices use 'smart LCD' displays to output visual information. LCD
displays designed around Hitachi's LCD HD44780 module, are inexpensive, easy to use,
and it is even possible to produce a readout using the 8x80 pixels of the display. They have
a standard ASCII set of characters and mathematical symbols.
3.5.1Signals to LCD
1. Enable
This line allows access to the display through R/W and RS lines. When this line is low, the
LCD is disabled and ignores signals from R/W and RS. When (E) line is high, the LCD checks
the state of the two control lines and responds accordingly
2.Read/write

AIET/ECE/PR/019

This line allows access to the display through R/W and RS lines. When this line is low, the
LCD is disabled and ignores signals from R/W and RS. When (E) line is high, the LCD checks
the state of the two control lines and responds accordingly.
3.6 Regulators
Battery balancing and battery redistribution refer to techniques that maximize a battery's
capacity to make all of its energy available for use and increase the battery's lifetime. A battery
balancer or battery regulator is a device in a battery pack that performs battery balancing.
[1]

Balancers are often found in Lithium ion battery packs for cell phones and laptop computers.
They can also be found in battery electric vehicle battery packs.
Typically, the individual cells in a battery have somewhat different capacities and may be at
different levels of state of charge (SOC). Without redistribution, discharging must stop when
the cell with the lowest capacity is empty (even though other cells are still not empty); this
limits the energy that can be taken from and returned to the battery.
Without balancing, the cell of smallest capacity is a weak point, it can be easily overcharged
or over-discharged while cells with higher capacity undergo only partial cycle. For the higher
capacity cells to undergo full charge/discharge cycle of the largest amplitude, balancer should
protect the weaker cells; so that in a balanced battery, the cell with the largest capacity can be
filled without overcharging any other (i. e. weaker, smaller) cell, and it can be emptied without
over-discharging any other cell. Battery balancing is done by transferring energy from or to
individual cells, until the SOC of the cell with the lowest capacity is equal to the battery's SOC.
Battery redistribution is sometimes distinguished from battery balancing by saying the latter
stops at matching the cell's state of charge (SOC) only at one point (usually 100% SOC), so that
the battery's capacity is only limited by the capacity of its weakest cell.
A full battery management system (BMS) might include active balancing as well as
temperature monitoring, charging, and other features to maximize the life of a battery pack


AIET/ECE/PR/020

Fig 3.3 Battery Regulator

Voltage Regulator L7805 (regulator), usually having three legs, converts varying input voltage
and produces a constant regulated output voltage. They are available in a variety of outputs.
The most common part numbers start with the numbers 78 or 79 and finish with two digits
indicating the output voltage. The number 78 represents positive voltage and 79 negative one.
The 78XX series of voltage regulators are designed for positive input. And the 79XX series is
designed for negative input.

Fig 3.4 Voltage regulator

3.7 Speed controller
To control the speed of fan PWM TECHNIQUE is used.
3.7.1 PWM technique

AIET/ECE/PR/021

Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is a modulation
technique that conforms the width of the pulse, formally the pulse duration, based on modulator
signal information. Although this modulation technique can be used to encode information for
transmission, its main use is to allow the control of the power supplied to electrical devices,
especially to inertial loads such as motors. In addition, PWM is one of the two principal
algorithms used in photovoltaic solar battery chargers,
[1]
the other being MPPT.
The average value of voltage (and current) fed to the load is controlled by turning the switch
between supply and load on and off at a fast pace. The longer the switch is on compared to the
off periods, the higher the power supplied to the load is

Normal case

Fig 3.5 For a pulse

Pulse width modulation

AIET/ECE/PR/022

Fig 3.6 High and low duty cycles.

3.8 L293D
The L293D is a popular motor driver IC that is usable from 6 to12V, at up to 1A total output
current. By itself, the IC is somewhat difficult to wire and use, but the Compact L293D Motor
Driver makes it much more convenient to use.

Board Special Features
Four motor direction indicator LEDS
Schottky EMF-protection diodes
Socket pin connectors for easy logic interfacing
Enable pins are user accessible

Fig 3.7 L293D
3.9 ADC 0804

AIET/ECE/PR/023

ADC0804 is a very commonly used 8-bit analog to digital convertor. It is a single channel IC,
i.e., it can take only one analog signal as input. The digital outputs vary from 0 to a maximum
of 255. The step size can be adjusted by setting the reference voltage at pin9. When this pin is
not connected, the default reference voltage is the operating voltage, i.e., Vcc. The step size at
5V is 19.53mV (5V/255), i.e., for every 19.53mV rise in the analog input, the output varies by
1 unit. To set a particular voltage level as the reference value, this pin is connected to half the
voltage. For example, to set a reference of 4V (Vref), pin9 is connected to 2V (Vref/2), thereby
reducing the step size to 15.62mV (4V/255).
ADC0804 needs a clock to operate. The time taken to convert the analog value to digital value
is dependent on this clock source. An external clock can be given at the Clock IN pin. ADC
0804 also has an inbuilt clock which can be used in absence of external clock. A suitable RC
circuit is connected between the Clock IN and Clock R pins to use the internal clock.

Fig 3.8 ADC0804
3.10 OptCoupler ILD 74
In electronics an opto-isolator, also called an optocoupler, photocoupler, or optical isolator, is
"an electronic device designed to transfer electrical signals by utilizing light waves to provide

AIET/ECE/PR/024

coupling with electrical isolation between its input and output". The main purpose of an opto-
isolator is "to prevent high voltages or rapidly changing voltages on one side of the circuit from
damaging components or distorting transmissions on the other side."Commercially available
opto-isolators withstand input-to-output voltages up to 10 kV and voltage transients with
speeds up to 10 kV.

FEATURES
ILD74, ILQ74 TTL compatible
Transfer ratio, 35 % typical
Coupling capacitance, 0.5 pF
Single, dual, and quad channel
Industry standard DIP packages
Compliant to RoHS Directive 2002/95/EC and
in accordance to WEEE 2002/96/EC

Fig 3.9 Opto-coupler ILD 74

Product information
OPTOCOUPLER, DUAL, TRANSISTOR O/P
No. of Channels: 2
Isolation Voltage: 5.3kV
Optocoupler Output Type: Phototransistor
Input Current: 20mA
Output Voltage: 20V
Opto Case Style: DIP

AIET/ECE/PR/025

No. of Pins: 8
Current Transfer Ratio Min: 12.5%
Current Transfer Ratio Typ: 12.5%
Forward Current If(AV): 16mA
Operating Temperature Max: 100C
Operating Temperature Min: -55C
Operating Temperature Range: -55C to +100C
The is an optically coupled pair with a Gallium Arsenide infrared LED and a silicon NPN
phototransistor. Signal information, including a DC level, can be transmitted by the device
while maintaining a high degree of electrical isolation between input and output. The IL74
is especially designed for driving medium-speed logic, where it may be used to eliminate
troublesome ground loop and noise problems. Also it can be used to replace relays and
transformers in many digital interface applications, as well as analog applications such as
CRT modulation. The ILD74 has two isolated channels in a single DIP package; the ILQ74
has four isolated channels per package


AIET/ECE/PR/026

CHAPTER 4
P89V51RD2 MICROCONTROLLER

4.1 Introduction
The P89V51RD21 is an 8051/8052-pin-compatible microcontroller by NXP (ex-Philips), with
64+8kB FLASH code memory, 768B internal RAM (ERAM/XRAM), 6-clock (x2) mode, and
a couple of extended peripherals, such as the PCA unit, SPI interface and watchdog counter.
The most remarkable feature is, however, that it's FLASH can be in-situ programmed (ISP)
through UART; and also its selfprogrammability (in-application programmability, IAP). The
P89V51RD2 is a successor to the successful P89C51RD+2/P89C51RD23 line, which
introduced the ISP/IAP paradigm to the higher-end FLASH-based 8-bit microcontrollers.
Microcontrollers with very features - 8051-pin-compatible, with up to 64kB of FLASH,
supporting IAP and ISP are manufactured by multiple manufacturers, including NXP's own
P89C66x/P89V66x4, Atmel AT89C51RD2/AT89C51ED25 (successor to the Temic
T89C51RD2), Nuvoton (ex-Winbond) W78ERD2A6 and SST
SST89E564RD/SST89E516RD7. Some of them offer also a mix of models with less FLASH
(and Atmel also a model with 128kB FLASH, the AT89C51RE2) and 3V supply voltage.
However, although they are remarkably similar, they usually significantly differ in the IAP/ISP
method. Some even don't have factory-installed bootloader, even if they usually offer free
bootloader firmware and associated PC software. As Philips/NXP phased out the P89C51RD2
in favour of P89V51RD2, users started to complain about the rather different nature of the IAP
procedure in the latter. This made NXP to introduce the P89CV51RD28 and family, which,
although physically closer to the newer P89V51RD2, mimics closer the original IAP behaviour
of the older P89C51RD2.


AIET/ECE/PR/027

4.2 Family members
There are also modifications to P89V51RD2 offered by NXP, besides the three packaging
options (traditional DIP40 and PLCC44, and the miniscule TQFP44 with 0.8mm pin pitch).
Devices with less FLASH are marked as P89V51RB2 for 16kB FLASH and P89V51RC2 for
32kB FLASH. Low supply voltage (3V) devices are marked as "LV", such as in
P89LV51RD29. Unfortunately, NXP currently does not offer wide supply voltage devices in
this family. As most of the characteristics are the same across the whole family, often,
"cumulative" marking such as "P89V51Rx2" is used to denote any member of the family.
However, throughout this document,
"P89V51RD2" will be used consistently, marking also other members of the family as
appropriate. There were several versions of the P89V51RD2 datasheet issued by Philips/NXP.
To avoid confusion, it is always a good idea to download the latest one. At the time of writing
of this document, the latest datasheet is marked as "Rev.4 - 1. May 2007"10.

4.3 P89V51RD2 and ISP
One of the key moments of success of the P89V51RD2's predecessors was the ability to
program them in-situ through UART. This alleviated the need for a costly parallel device
programmer, or even a specialised programming "cable"; which made these microcontrollers
attractive for small enterprises and hobbyists, despite their higher price. It also allows easy
field-update of firmware from any PC or other device equipped with standard serial port.
The P89V51RD2 continued in this trend, although with a slightly different communication
protocol, and, more importantly, a different bootloader entry method. On the older models,
bootloader was entered when a particular set of voltage levels was applied to various pins
(including the PSEN/ pin). On P89V51RD2, after reset, the bootloader waits for a
predetermined time, until a "U" character (55h) arrives to the UART receiver. The datasheet
states this time as "approximately 400ms", however, as it is in fact derived from the watchdog,
this time is dependent on the system clock frequency, being around 400ms when fCLK is
approx. 3.5MHz; for other clock frequencies this time is proportionately shorter or longer. This
autobaud method has both its advantages and drawbacks. On one hand, it does not tie down any

AIET/ECE/PR/028

pin and does not require any extra hardware nor manipulation with shorting jumpers or
switches, as the old entry method did. On the other hand, in applications where an external
device sends continuous stream of data to the P89V51RD2's UART, upon reset, the bootlader
may be entered inadvertently. The extra delay before the application itself starts, may be a
hindrance in certain applications, too.
The autobauding process itself is not quite perfect either. It derives the UART's baudrate
coefficient by measuring the time between a trailing and a leading edge on the RxD pin (i.e.
duration of a "0" bit). It then starts the UART and waits for the "U" character. As the
"measurement" involves a certain granularity (uncertainty in the edges detection by bootloader
firmware), moreover on RS232/UARTs usually some small asymmetry between duration of 0s
and 1s exists, there is a chance of errorneous detection of baudrate, even if a crystal normally
allowing precise setting of a given baudrate is used11. The probability of correct baudrate
detection generally increases with lower baudrates, so the conservative recommendation is to
use 9600 Bauds or below, even if this may lead to increased programming times. To start the
autobauding, usually the P89V51RD2-containing device is simply powered up; however, in
some cases a simple circuit triggering reset from some of the handshake lines (RTS, DTR) is
built to the device, for added comfort. This then has to be handled by the PC-side software
accordingly. (Note, that FlashMagic by default assumes such hardware to be present, which
may cause unexpected behaviour of FM if this hardware is absent).
The ISP protocol is entirely ASCII based, and uses intelhex-like "records" to perform various
FM (except for the response during FLASH readout, which can perhaps be described as "raw
ascii hexadecimal with spaces"). This allows to use as a PC-side programming utility any
general-purpose terminal emulator, such as the ubiquitous Hyperterminal, or Tera Term12 on
Windows, or minicom13 on Linux/Unix-like OS. Autobauding can be performed "by hand",
pressing and holding down the "U" key and relying on the keyboards autorepeat, while
resetting the target device. Commands for device identification (which serves as the successful
autobauding verification) and erasing can be either "typed in", or "uploaded" from a previously
prepared file, if needed. The FLASH content itself, as it is programmed using the "normal" type
00 intelhex fields, found in the .hex files output from compilers and assemblers, can be simply
"uploaded" from these files; to allow time for programming, an inter-line delay of some 100ms
has to be set. Even if possible, the above described "manual" method is rather tedious and may

AIET/ECE/PR/029

serve only as a backup emergency method of programming. The standard PC-side application
for programming is FlashMagic (by ESAcademy)14. There is also a FlashMagic forum15, with
an extensive bootloading troubleshooting list16.

4.4 Characteristics of FLASH in P89C51RD2
The code FLASH in P89C51RD2 consists of two big blocks:
- Block0, 64kB, mapped at 0000h-0FFFFh, intended to run the "normal" user application.
- Block1, 8kB, mapped at 0000h-1FFFh, containing the bootloader.
As the two blocks overlap in the 0000h-1FFFh area, which of them is "visible" is determined
by two bits in the FCF special function register. The FLASH can be written byte-by-byte. As is
usual with FLASH, bytes have to be erased prior to be written. An erased byte contains 0FFh.
FLASH can be erased by 128-byte sectors (pages), or by a whole block (using an external
parallel device programmer, a third method, full chip erase, is also possible - this erases both
blocks, the x2 flag and the security flag in one operation). During writing/erasing, execution is
not possible, so the code writing to Block0 must reside in Block1 (i.e. the bootloader code has
to be called to perform the write/erase in Block0).
The datasheet states endurance as 10.000 cycles and retention to 100 years, which together with
the relatively small sector size makes the FLASH suitable for ocassionally rewritten data
storage (EEPROM replacement e.g. for device setup parameters). The datasheet completely
fails to specify erase and write times... Note, that the datasheet specifies a minimum clock
frequency, 0.25MHz, for in-application programming. The datasheet does not specify supply
current during programming, but a safety margin of a few tens of mA over the specified
"normal" supply current, and decent supply decoupling, could never hurt.
According to the datasheet, there is a single (non-volatile) security bit, preventing reading of
the FLASH using parallel programmer. This bit can be set both by parallel programmer and
during ISP or IAP. This bit does not influence device readout through ISP (which has an
independent security mechanism, basedon a "serial number", see below), nor IAP.

4.5 IAP
In-application programming (IAP) of Block0 FLASH in P89V51RD2 is performed through
setting up a couple of registers, and making a call to a predetermined address - 1FF0h - in

AIET/ECE/PR/030

Block1. This, and a list of possible operations together with the related registers (Table 13,
which we are not going to reproduce here, and the reader is requested to study it thoroughly), is
roughly all the datasheet says about IAP. The reality is somewhat more complex. As said
above, the code performing programming of FLASH Block0 has to run from Block1. This is
why the IAP routines are part of the default bootloader in Block1. So, to be able to run these
routines, Block1 must be mapped as active at the lower part of code address space, 0000h-
1FFFh. This is accomplished through clearing both SWR and BSEL bits in FCF special
function register. Note, that this step has two consequences:- the code "switching" the blocks
(i.e. clearing both mentioned SFR bits) must lie above the "shared" area, i.e. within 2000h-
FFFFh. It is handy therefore to create a short routine, which handles the FLASH block
switching and the IAP entry point (1FF0h) call - see CallIAP routine in the example below
and locate it at some suitable high address. As it is with absolutely located routines, it must be
made sure, that it is not overlapped with some other routine. In most applications, a location
near the top of the available FLASH might be a suitable place. - before the blocks switching,
interrupts must be disabled. After blocks switching, the interrupt vector area at the beginning of
code address space is occupied by Block1, with the default bootloader. As the default
bootloader has no provisions for interrupt handling, any interrupt which would occur while
Block1 is "visible", would execute some random code, leading to crash. After return from the
IAP routines, Block0 can be restored by setting BSEL bit (SWR bit is supposed to be set only
by hardware), after which interrupts may be reenabled. Using IAP, any byte in Block0 can be
programmed, including the 0000h-1FFFh area. Care has to be practiced, of course, if areas with
"living" code are programmed or erased, including the interrupt vector area. However, only
bytes which contain 0xFF (i.e. which are erased) may be programmed. This means, that if a
non-0xFF byte has to be reprogrammed, the 128-byte sector where this byte is located has to be
erased. If other bytes in this sector have to be preserved, they must be stored into RAM
(ERAM) before erasing and then reprogrammed back to that sector. The IAP "protocol"
contains confusing commands, too. There is a command for block 0 erase, which is a complete
nonsense, as the routine calling IAP would be erased, too, and there would be no code to return
to (an effective "suicide" of the application"). There is also a command for byte read, which is
much easier to perform using some of the MOVC instructions. Note also, that the datasheet
does not specify resources used by the IAP routines. Even if these can be determined by

AIET/ECE/PR/031

disassembling the bootloader, there is no guarantee these will not change in some future
versions. Some of the potentially problematic issues include:- stack usage - the IAP routines
perform at least two nested calls, so a conservative approach would be to reserve around 10
bytes of stack for the IAP- register usage - a conservative approach would assume that all
registers R0-R7 of the current bank, B and DPTR are changed bye IAP routines - memory and
SFR usage - it is unlikely that the IAP calls would use any memory and/or SFR (except the
FLASH interface SFRs, which are undocumented anyway) - sensitivity to register bank setting,
and possible change to it - if the bootloader code would use absolute addressed registers, it
would be sensitive to the particular register bank at the moment of IAP call. A conservative
approach would be to stick to register bank 0 when calling IAP routines.
However, it is unlikely that the IAP routines would actively change the bank. - sensitivity to
DPTR selection, and possible change to it - it is unlikely that the IAP routines would be
sensitive to which DPTR is currently selected. It is also unlikely they would change the DPTR
selection or modify the other than currently selected DPTR. Timing of the IAP routines is also
not specified. Read commands are certainly served within several tens of instruction cycles, but
programming commands take certainly more time. A conservative estimate would be, that
programming a single byte takes a couple of milliseconds, whereas a sector erase might take
tens of milliseconds, and a block erase up to several seconds. Timing of IAP routines, i.e. the
time while the mcu is essentially out of the user's control, has to be taken into account not only
for timer-based operations (including the PCA), but also for UART operation and SPI slave
operations. Handshaking with the other-side device has to be employed wherever applicable.
Another timing-sensitive issue is the watchdog, which has to be served just before and after the
IAP call, or, if this is insufficient, disabled during IAP (although disabling watchdog is
generally a bad idea).

4.6 Pin description
Port 0: Port 0 is an 8-bit open drain bi-directional I/O port. Port 0 pins that have 1s written to
them float, and in this state can be used as high-impedance inputs. Port 0 is also the
multiplexed low-order address and data bus during accesses to external code and data memory.
In this application, it uses strong internal pull-ups when transitioning to 1s. Port 0 also

AIET/ECE/PR/032

receives the code bytes during the external host mode programming, and outputs the code bytes
during the external host mode verification. External pull-ups are required during program
verification or as a general purpose I/O port.
Port 1: Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 pins are
pulled high by the internal pull-ups when 1s are written to them and can be used as inputs in
this state. As inputs, Port 1 pins that are externally pulled LOW will source current (IIL)
because of the internal pull-ups. P1.5, P1.6, P1.7 have high current drive of 16 mA. Port 1
also receives the low order address bytes during the external host mode programming and
verification.

AIET/ECE/PR/033

Fig.4.1: Pin diagram of microcontroller P89V51RD2
T2: External count input to Timer/Counter 2 or Clock-out from Timer/Counter 2.
T2EX: Timer/Counter 2 capture/reload trigger and direction control.

AIET/ECE/PR/034

ECI: External clock input. This signal is the external clock input for the PCA.
CEX0: Capture/compare external I/O for PCA Module 0. Each capture/compare module
connects to a Port 1 pin for external I/O. When not used by the PCA, this pin can
handle standard I/O.
SS: Slave port select input for SPI.
CEX1: Capture/compare external I/O for PCA Module 1.
MOSI: Master Output Slave Input for SPI.
MISO: Master Input Slave Output for SPI.
SCK: Master Output Slave Input for SPI.
Port 2: Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. Port 2 pins are pulled
HIGH by the internal pull-ups when 1s are written to them and can be used as inputs in this
state. As inputs, Port 2 pins that are externally pulled LOW will source current (IIL) because of
the internal pull-ups. Port 2 sends the high-order address byte during fetches from external
program memory and during accesses to external Data Memory that use 16-bit address. In this
application, it uses strong internal pull-ups when transitioning to 1s. Port 2 also receives some
control signals and a partial of high-order address bits during the external host mode
programming and verification.
Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins are pulled
HIGH by the internal pull-ups when 1s are written to them and can be used as inputs in this
state. As inputs, Port 3 pins that are externally pulled LOW will source current (IIL) because of
the internal pull-ups. Port 3 also receives some control signals and a partial of high-order
address bits during the external host mode programming and verification.
RXD: serial input port
TXD: serial output port
INT0: external interrupt 0 input
INT1: external interrupt 1 input
T0: external count input to Timer/Counter 0
T1: external count input to Timer/Counter 1

AIET/ECE/PR/035

WR: external data memory write strobe
RD: external data memory read strobe
Program Store Enable: PSEN is the read strobe for external program memory. When the
device is executing from internal program memory, PSEN is inactive (HIGH). When the device
executing code from external program memory, PSEN is activated twice each machine cycle,
except that two PSEN activations are skipped during each access to external data memory. A
forced HIGH-to-LOW input transition on the PSEN pin while the RST input is continually held
HIGH for more than 10 machine cycles will cause the device to enter external host mode
programming. RST 9 4 10 I Reset: While the oscillator is running, a HIGH logic state on this
pin for two machine cycles will reset the device. If the PSEN pin is driven by a HIGH-to-LOW
input transition while the RST input pin is held HIGH, the device will enter the external host
mode, otherwise the the device will enter the normal operation mode.
External Access Enable: EA must be connected to VSS in order to enable the device to fetch
code from the external program memory. EA must be strapped to VDD for internal program
execution. However, Security lock level 4 will disable EA, and program execution is only
possible from internal program memory. The EA pin can tolerate a high voltage of 12 V. ALE/
PROG 30 27 33 I/O Address Latch Enable: ALE is the output signal for latching the low byte
of the address during an access to external memory. This pin is also the programming pulse
input (PROG) for flash programming. Normally the ALE is emitted at a constant rate of 16
the crystal frequency and can be used for external timing and clocking. One ALE pulse is
skipped during each access to external data memory. However, if AO is set to 1, ALE is
disabled.
Crystal 1: Input to the inverting oscillator amplifier and
input to the internal clock generator circuits.
Crystal 2: Output from the inverting oscillator amplifier.


AIET/ECE/PR/036

CHAPTER 5
CODING

4.0 Coding
sfr P0=0x80;
sfr P1=0x80;
sfr P1=0x90;
sfr P2=0xA0;
sfr P3=0xB0;
sbit relay = P1^0;
Sbit inc = P1^1;
sbit dec = P1^2;
#define adcdata P3
sbit intr = P2^2; //5
sbit rd =P2^0; //2
sbit wr =P2^1; //3
sbit rs = P2^5;
sbit rw = P2^6;
sbit en = P2^7;
unsigned char line[4] = {0x80,0xC0,0x90,0xD0};
#define DBUS P0
#define BLINKLCD 0x09
#define ONCURSOR 0x0A
#define ONLCD 0x0C
#define CLEARLCD 0x01
#define HOMELCD 0x02

AIET/ECE/PR/037

#define ENTRYMODE 0x06
#define FUNCSET 0x38
void wrlcd_cmd(unsigned char cmd );
void wrlcd_data(unsigned char Data );
void delay(unsigned int count);
void wrmsg(char LineNo,char endloc, unsigned char msg[]);
void getdata();
static unsigned char sp=0;
code unsigned char scr5[2] [16] = {" Temp: ", " SP: "};
code unsigned char scr1[2] [16] = {" JAY Patel " " BSPP 2
nd
SHIFT "};
void main( )
{
unsigned char i;
unsigned char x,d1,d2,d3,val,a=0;;
P3=0xff;
P0=0x00;
P2=0x0f;
relay=0;

wrlcd_cmd(FUNCSET); //set data length,no of disp,2-line display
wrlcd_cmd(ONLCD); //display and cursor on
wrlcd_cmd(ENTRYMODE); //inc. DDram address,
wrlcd_cmd(CLEARLCD); //Clear display
for(i=0;i<2;i++)
{
delay(100);
wrmsg(line[i],16,scr1[i]);
}
for(i=0;i<15;i++)

AIET/ECE/PR/038

delay(50000);
for(i=0;i<2;i++)
{
delay(100);
wrmsg(line[i],16,scr5[i]);
}
while(1)
{
wr=0;
delay(100);
wr=1;
while(intr != 1);
while(intr != 0);
rd=0;
delay(10);
val=adcdata;
rd=1;
wrlcd_cmd(line[0]+9);
x=val/10;
d1=val%10;

AIET/ECE/PR/039

d2=x%10;
d3=x/10;
wrlcd_data(d3+0x30);
delay(10);
delay(10);
a=(d3*100)+(d2*10)+d1;
wrlcd_data('C');
wrlcd_cmd(line[1]+9);
wrlcd_data((sp/10)+0x30);
wrlcd_data((sp%10)+0x30);

if(inc==0)
{
while(inc==0);
sp++;
}
if( (dec==0) && sp>0 )

while(dec==0);
sp--;
}
if(a>sp)

AIET/ECE/PR/040

relay=1;
else
relay=0;
delay(25000);
}
}
void wrlcd_cmd(unsigned char cmd)
{
DBUS = cmd;
delay(10);
rs = 0; //select cmd reg
delay(10);
rw = 0; //write mode
delay(10);
en = 1;
delay(300);
en = 0;
delay(20);
}
void wrlcd_data(unsigned char Data )
{
DBUS = Data;
delay(10);
rs = 1; //select data reg

AIET/ECE/PR/041

delay(10);
rw = 0;
delay(10);
en = 1;
delay(300);
en = 0;
delay(10);
rs = 0;
delay(20);
}
void wrmsg(char LineNo,char endloc, unsigned char msg[])
{
unsigned char i;
wrlcd_cmd(LineNo);
for(i =0;i<=endloc;i++)
{
wrlcd_data(msg[i]);
delay(50);
}
}

void delay(unsigned int dly)
{
while(dly>0)
dly--;

AIET/ECE/PR/042

}
RESULT
We have successfully completed the project. It is now in full working position. On connecting
it to a 12 v battery and providing the required temperature specifications as given, the fan can
automatically turn on and off, varying from the range of -45
0
C to 120
0
C. The temperature
sensing is being done by the LM35 and the fan is being driven by the stepper motor attached to
it which drived the speed of the fan as per the requirement and the temperature changes.
Through this project we got to learn many more in the depth starting from the designing of the
PCB to the final running of the project, and working as a team was extremely fabulous
experience, sharing thoughts and knowledge at the same time and assisting each other in the
best possible way we could. Also implementing our engineering learnings ws a good
experience.


AIET/ECE/PR/043

APPLICATION
1. For cooling fans of laptop and personal computers more efficiently and dont taking any
risk as soon as the temperature rises. Generally fan in pc and laptops comes with two or
three possible speeds that results in more power consumptions. So temperature
controlled fan can accomplish that job efficiently.
2. In trains where power is wasted due to ignorant passengers
3. In public halls like community halls.
4. Useful for physically challenged people.
5. Useful for automatic control in places where temperature varies frequently with day and
night means those close to shore and sandy areas.


AIET/ECE/PR/044

FUTURE DEVELOPMENT
1. It can lead to the saving of enormous power and thus reduce the extra expenditure done
of the power in our country thereby raising the economy of our country.
2. It can also be charged with solar cells when used in open areas and thus prove to be
very efficient.
3. It can be used for several automation purposes.
4. It can lead to automation in trains and metros.


AIET/ECE/PR/045

CONCLUSION
We did the project with a fan with fixed speed and fixed PWM duty cycle for 10 degree
centigrade interval from 25 to 65 degree Celsius. Care should be taken that such delays should
not affect the open loop control system performance. Temperature should not vary abruptly
otherwise it would degrade the performance of the system and the fan as a whole.
In conclusion, the objective to build an the temperature controlled fan was successfully
achieved. In terms of performance and efficiency, this project has provided a convenient
method. This system is also a user friendly system However, some further improvements can
be made on this in order to increase its reliability and effectiveness.


AIET/ECE/PR/046

REFERENCES

1. http://researchgate.net/publication/235598499_automation - /file/d91.pdf
2. http://seminarprojects.com/s/TCF
3. http://psocrfid.blogspot.in/2011/4/TCF
4. http://dnatechindia.com/projects
5. http://wikipedia/components_tempcontrolled fan
6. http://wikipedia/microcontroller


AIET/ECE/PR/047

COST
S. No. Name of Components Cost (Rs.)
1 P89V51RD2 Microcontroller 250
2 LCD Display 150
3 ADC 110
4 Potentiometer 5
5 Fan with DC motor 20
6 L293D 40
7 5V Adapter 150
8 12 V Adapter 200
9 Resistors 10
10 Capacitors 20
11 Copper plate 20
12 Connecting wires 10
13 Soldering wire 10
14 Glossy papers 10
15 Total cost 925


AIET/ECE/PR/048

Temperature Controlled Fan

Uploaded by

Copyright:

Available Formats

Temperature Controlled Fan

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

Temperature Controlled Fan

Uploaded by

Copyright:

Available Formats

Temperature controlled fan with display

You might also like