This document describes a smart home system that automatically controls fan speed and lighting based on temperature and light intensity readings. The system uses a microcontroller, LCD display, temperature sensor, light sensor, motor driver, and relays to vary the fan speed based on room temperature between 25-45 degrees Celsius and switch lights on/off based on light intensity above or below 150 units. It also tracks the number of people in the room and turns everything off when unoccupied to save power.

1. PREDEFINED HARDWARE
TEAM-: MELODY
1)ASHUTOSH YADAV
2)ARCHIT RASTOGI
3)AMAN SAXENA
4)ANURAG ARYA

2. INTRODUCTION
IN INDIA MOST OF THE RURALS STILL ARE FACING
THE PROBLEM OF ELECTRICITY CRISIS, WHEREAS IN
CITIES A LOT OF POWER IS WASTED.
WE AS A CITIZEN OF INDIA HOLD THE
RESPONSIBILITY FOR THE RATIONAL USE OF ENERGY.
THIS SYSTEM HELP IN HOUSEHOLD POWER USAGE.

3. PROBLEM STATEMENT
PRIMARY TASK-:
The speed of the electric fan, presently, can be varied
in steps by the regulating knob. Here the task is to
replace this traditional knob, automatically vary the
fan speed in accordance with the environmental
temperature.
The temperature and the speed should be displayed
on some displaying unit i.e. LCD.

4. SECONDARY TASK
The intensity of the light in the room should be continuously
monitored and bulbs, etc. should be automatically switched ON and
OFF accordingly i.e. the lights should be switched ON if the light
intensity falls below a critical value and vice-versa. Display the light
condition as DARK or OPTIMUM on LCD.
There should be a visitor counter which checks the no. of persons
currently present in the room. When there is no human presence in
the room then the lights and the fans should be switched OFF and
thus saving the precious power.
In spite of this automatic version, Provision of a Manual key should
be there, which if pressed, disables the automatic mode at any
time.

5. COMPONENTS
MICROCONTROLLER(ATMEGA32)
• It is a small computer on a single integrated
chip. Contains processor core, RAM/ROM ,
EEROM, programmable I/O ports and a Timer.

7. LIQUID CRYSTAL DISPLAY(LCD)
Now we need to interface an LCD to our microcontroller so
that we can display messages, outputs, etc. We will use the
16x2 LCD, which means it has two rows of 16 characters each.
Hence in total we can display 32 characters.

8. L298
The L298 is an integrate
monolithic circuit in a 15 -
lead Multiwatt.
It is a high voltage, high
current dual full-bridge
driver designed drive
inductive loads such as
relays, solenoids, DC and
Stepping motors.
Operatng supply upto 46
volt and dc current upto 4.5
A.
Over temperature
protection.

9. LIGHT DEPENDENT
RESISTANCE(LDR)
Normally the resistance of an LDR is
very high, sometimes as high as
1000 000 ohms, but when they are
illuminated with light resistance
drops to 100 ohms.
The LDR must be part of a voltage
divider circuit in order to give an
output voltage, Vout , which
changes with illumination.
When no light falls on the LDR,
very high resistance shown by the
LDR hence Vout will be very low.
And when light falls on the LDR,
very Low resistance shown by the
LDR hence Vout will nearly be equal
to the Vin applied. Hence the two
conditions can be distinguished.

10. SENSOR NETWORK
• We have used the fundamental that
the white surface reflects almost all the
light falling on it whereas the black
surface absorbs maximum light falling
on it.
• Our arena would be a black surface all
over with white strips showing the way
to travel. With keeping LED lights
always ON and using the above
principle our LDR will get different light
intensities when on the two different
surfaces i.e. black and white.
• Hence we would be able to detect our
present position of the sensor whether
it is on Black or on White and will now
act accordingly.

11. lM7805
7805 voltage regulator is used
to get +5 V output out of a
higher voltage supply (7.5V-
20V).We use adapter’s supply
to generate +5V here. Connect
the gnd and +12V of adapter
to the pins as shown and get
+5V directly as an output out
of the 3rd pin. Current up to
0.5 A can be obtained from
this regulator without any
significant fall in voltage level.

12. LM 35
Operates from 4 to 30 volts
Calibrated directly in
Celsius
Measure temperature and
accordingly we take output.
In this, we use this to
control the bulb on off
phenomenon.

13. RELAYS
• A relay is
an electrically operated switch.
• Many relays use
an electromagnet to operate a
switching mechanism
mechanically.
• Relays are used where it is
necessary to control a circuit by a
low-power signal (with complete
electrical isolation between
control and controlled circuits),
or where several circuits must be
controlled by one signal.

14. 1)For temperature less than 25degree celcius the
fan will stop and “COOL TEMPRETURE “ will
print on lcd.
2)For tempreture more than 45 degree celcius the
fan will stop and “NO FAN” will print on lcd.
3)For tempreture in between 25 to 45 degree
celcius the speed of the fan will change according
to the tempreture of the room. the speed of fan will
be printed along with the tempreture on lcd.

15. 1)If the light intensity is less than 150 then
“DARK” will print on lcd along with the
intensity and the bulb will switch on.
2)If the light intensity is more than 150 then
“OPTIMUM” will print on screen along with
the intensity and the bulb will switch off.

16. CIRCUIT DIAGRAM

17. CONCLUSION
Fan speed will be varied according to temperature
present in room.
Bulb will be switched on/off according to light
intensity.
Visitor counter help in power supply on/off according
to people present in the room.
With the help of key, automatic working can be
converted in manual working.
With the help of micro controller, lcd, lm7805, l298,
relay, uln2003a. lm35, ldr, motor, bulb.