Automatic room light controller with visitor counter

1. K682 - Automatic Room Light Controller with Visitor Counter Page 1
Automatic Room Light Controller with Visitor Counter
K-682
This Project "Automatic Room Light Controller with Visitor Counter" is a reliable circuit that takes over
the task of controlling the room lights as well us counting number of persons/visitors in the room very
accurately. When somebody enters into the room then the counter is incremented by one and the light in
the room will be switched ON and when any one leaves the room then the counter is decremented by
one. The light will be only switched OFF until all the persons in the room go out. The total number of
persons inside the room is also displayed on the seven segment displays.
Visitor counting is simply a measurement of the visitor traffic entering and exiting offices, malls,
sports venues, etc. Counting the visitors helps to maximise the efficiency and effectiveness of
employees, floor area and sales potential of an organisation. Visitor counting is not limited to the
entry/exit point of a company but has a wide range of applications that provide information to
management on the volume and flow of people throughout a location. A primary method for counting the
visitors involves hiring human auditors to stand and manually tally the number of visitors who pass by a
certain location. But human-based data collection comes at great expense.
Specifications & Features
 Micro controller based interface using Atmel AT89C2051
 Infrared Sensor Based Detection
 Entry and exit detection
 Counting up to 9999 (4 digit)
 Relay based switching output for external load
 Relay output – 230V AC/DC-3A rated changeover contacts (See the data sheet of Relay)
 4 digit seven segment LED Display
 Adjustable IR Detection Range
 Relay status and IR Detection LED indicator
 Diode protection for reverse polarity connection of DC supply to the PCB
 Onboard regulator for regulated supply to the kit
 Power supply: 8 to 12V DC Input
 Operating Current - 500ma Aprox
CIRCUIT EXPLANATION
MICROCONTROLLER INTERFACE
See the block diagram of unite. It’s based on a pre programmed Atmel AT89S5x micro controller.
The circuit used in this kit uses only one IC – the AT89C2051. It is one of the 8051-based micro
controllers from ATMEL. The IC is pre programmed. Using a micro controller greatly reduces the
component count while providing more features than could be found using dedicated logic ICs. Cost is
also lower. It is pre-programmed with software to provide all the timing functions.
The microcontroller does the above job. It receives the signals from the sensors, and this signal is
operated under the control of software which is stored in ROM. Microcontroller continuously monitor the
IR Sensors, When any object pass through the IR sensor generates a pulse and interrupt controller. So
visitors in the room are counted up by Sensor1 and Sensor2 counts visitors going out of room. As soon
as visitor count reaches 0 the room light turns off. Room lights switched on and off Via 12V SPDT Relay
MCU Cock
Clock signal for the micro controller provided by crystal X1 (11.0592 MHZ) and two 33PF (C2, C3)
capacitors hanging off it ensure correct loading for the crystal, so that it starts reliably. The frequency of
the oscillator is internally divided and to get the operating frequency. This high frequency clock source is
used to control the sequencing of CPU instruction.
MCU Reset
Power on reset is provided by R13 and C1. The 89C2051 micro controller has an active high reset signal

2. K682 - Automatic Room Light Controller with Visitor Counter Page 2
IR Object detection Sensor Module
The sensor senses the light reflected from the objects and feeds the output to the comparator. When the
sensor is above the objects the light falling on it from the source reflects to the sensor, The sensor
senses the reflected light to give an output, which is fed to the comparator.
The comparator compares the analogue inputs from sensors with a fixed reference voltage. If this
voltage is greater than the reference voltage the comparator outputs a low voltage, and if it is smaller the
comparator generates a high voltage that acts as input for the decision-making device (microcontroller).
IR Sensor Module interface to micro controller via, Port P3.0 and P3.1 (pin no 2 and 3)
LED Display interfacing
We can now interface a four digit 7-Seg to the micro controller. We use Scanning (Multiplex) Principle
where one 7-seg is displayed after another but this process is very fast hence the flickering cannot be
seen by human eye. In the circuit diagram shows the circuit for interfacing four digit 7 segment displays.
When interfacing more than one 7-seg display the segment's (A to G) of all displays are connected
together whereas their ANODE are switched ON one after another. Consider we have to display '27' on
the above 7-seg display so we TURN ON the first transistor by setting its corresponding pin to 1 & then
give the 7-seg equivalent code for '2'. Then we TURN OFF the first transistor & TURN ON the second &
output its corresponding 7-seg equivalent code of '7' .Then we again go back to display '2' this is a never
ending loop.
This minimizes the number of pins needed to drive the display but requires a more complex method to
do it. Multiplexing is a technique where each display is “active” for a short period of time. In this kit, each
digit is turned ON once every 8mS for a period of 1mS. There is an OFF time of 1mS between digits.
Resistors R1 - 8 limit the maximum current that can flow through each segment. Transistors Q1 and Q4
provide power to each digit.
RELAY INTERFACE
A single pole dabble throw (SPDT) relay is connected to port P3.7 of the micro controller through a driver
transistor. Relay is used to switch the external load like external light, fan ETC. The relay requires 12
volts at a current of around 100 ma, which cannot provided by the micro controller. So the driver
transistor is added. Normally the relay remains off. As soon as pin of the micro controller goes high, the
relay operates. When the relay operates and releases. Diode D2 is the standard diode on a mechanical
relay to prevent back EMF from damaging Q5 when the relay releases. LED L1 indicates relay on.
HOW to Connect Load with Relay?
When the project is working and according to its load, it could happen an incorrect operating of the
output. If it is the case, you have to install a circuit between 2 relay's contacts used for the connection.
See the drawing map.
The output of the projects is controlled by a relay, allowing any load until 230V AC / 3 Amp. as maximum
consumption. The relay has 3 output terminals the normally open at quiescent (NO), the normally closed
at quiescent (NC) and the common. The operating of this mechanism is the same as a switch with two
(2) terminals NO and common, if you wish that the output will be activated during the timer, or between
the NC and the common to obtain the reverse operating. In the drawing, you could appreciate the typical
connection for a devices operating at 12 VDC and to operate at 230 VAC.

3. K682 - Automatic Room Light Controller with Visitor Counter Page 3
When the project is working and according to its load, it could happen an incorrect operating of the
output. If it is the case, you have to install a circuit between 2 relay's contacts used for the connection.
See the drawing map.
Power supply
The power supply circuit. It’s based on 3 terminal voltage regulators, which provide the required
regulated +5V and unregulated +12V.
The DC 12V AT 500MA applies to the circuit via CN2. The 12V DC output is filtered by capacitor C4.
Regulators IC LM7805 (U2) provides regulated 5V power supplies, for Micro controller and LED Display
and other logic circuitry. Capacitors C6 and C7 bypass any ripple in the regulated outputs. Diode D1
protects against reverse polarity connection of the input power. The unregulated voltage of
approximately 12V is required for relay driving circuit
PART EXPLANATION
MICRO CONTROLLER AT89C2051
The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with 2K bytes of Flash
programmable and erasable read-only memory (PEROM). The device is manufactured using Atmel’s
high-density non-volatile memory technology and is compatible with the industry-standard MCS-51
instruction set. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel
AT89C2051 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to
many embedded control applications.
Compatible with MCS®-51Products
2K Bytes of Reprogrammable Flash Memory
2.7V to 6V Operating Range
Two-level Program Memory Lock
128 x 8-bit Internal RAM
15 Programmable I/O Lines
Two 16-bit Timer/Counters
Six Interrupt Sources
Programmable Serial UART Channel
Direct LED Drive Outputs
On-chip Analog Comparator

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6. K682 - Automatic Room Light Controller with Visitor Counter Page 6
Photodiodes are similar to regular semiconductor diodes except that they may be either exposed (to
detect vacuum UV or X-rays) or packaged with a window or optical fiber connection to allow light to
reach the sensitive part of the device. Many diodes designed for use specifically as a photodiode will
also use a “PIN” junction rather than the typical “PN” junction.
Infrared light-emitting (IR LED – IR1-2)
An infrared light-emitting diode (LED) is a type of electronic device that emits infrared light not visible to
the naked eye. An infrared LED operates like a regular LED, but may use different materials to produce
infrared light. This infrared light may be used for a remote control, to transfer data between devices, to
provide illumination for night vision equipment, or for a variety of other purposes.
An infrared LED is, like all LEDs, a type of diode, or simple semiconductor. Diodes are designed so that
electric current can only flow in one direction. As the current flows, electrons fall from one part of the
diode into holes on another part. In order to fall into these holes, the electrons must shed energy in the
form of photons, which produce light.
Operational amplifier (LM358)
An Operational amplifier ("op-amp") is a DC-coupled high-gain electronic voltage amplifier with a
differential input and, usually, a single-ended output.[1] An op-amp produces an output voltage that is
typically hundreds of thousands times larger than the voltage difference between its input terminals.[2]
Operational amplifiers are important building blocks for a wide range of electronic circuits. They had their
origins in analog computers where they were used in many linear, non-linear and frequency-dependent
circuits. Their popularity in circuit design largely stems from the fact the characteristics of the final
elements (such as their gain) are set by external components with little dependence on temperature
changes and manufacturing variations in the op-amp itself.
Op-amps are among the most widely used electronic devices today, being used in a vast array of
consumer, industrial, and scientific devices. Many standard IC op-amps cost only a few cents in
moderate production volume; however some integrated or hybrid operational amplifiers with special
performance specifications may cost over $100 US in small quantities. Op-amps may be packaged as
components, or used as elements of more complex integrated circuits.
Assembly
Use the component overlay on the PCB to place the components starting with the lowest height
components first. Make sure that the diode, LED and electrolytic capacitors are inserted the right way
around.
First check the components supplied in the Kit against the Component listing. Identify all the
components. It is generally best to solder the lowest height components first: the IC SOCKETS,
resistors, & diodes. The IC socket should be installed first. Begin solders the pin of the socket. The entire
resistor should be installed next. In order to find their values you have to check the colour code. All the
diode should be installed next. Make sure to get the diodes the correct way around. Match up the bar on
the diodes with the bar on the overlay. Afterwards solder the capacitors, transistors, LED display & other
remaining components. Especially care should be taken in order to find the polarity of the electrolytic
capacitors.

7. K682 - Automatic Room Light Controller with Visitor Counter Page 7
Note: - Please before assemble the kit; please see the photograph of assembled projects or
demonstration video. (Included in CD)
Use the component overlay on the PCB to place the components in the following order
1. Resistors and diodes
2. IC sockets
3. Ceramic capacitors and Preset.
4. Seven segment LED display
5. LM7805 regulators. Use needle nosed pliers to bend the leads of the regulator. It does not
require a heat sink. Screw down onto to PCB.
6. Crystal, LED’s, Photo diode, IR LED’s and transistors. (Especially care should be taken in order
to find the polarity of the LED, Photo diode and IR LED’s)
7. Electrolytic capacitors. Make sure you insert them the correct way around. Mount C6 (1000uf)
Capacitor Horizontal
8. Relay, and Electrolytic capacitor’s
NOTE: The PCB was designed such that the main micro controller PCB & Sensor PCB may be
separated. Interconnection of two PCBs is achieved with a short length of ribbon wire or burg strip
connector
Placement of IR LED (IR 1 - 2) and Photo Diode (PT1 - 2)
Bend the leads and Photo diode (PT and IR) down at right angles, about 3mm from the LED body, as
shown below. Use a pair of long nose pliers to hold the leads while bending. Cut the leads off to a
length of about 9mm from the bend Position. Please see the photograph of assembled projects.
(Included in CD)
REFERENCES
www.atmel.com
For a datasheet on the AT89C2051 micro controller
www.national.com / www.ti.com
For a datasheet on the LM7805 or LM358

8. K682 - Automatic Room Light Controller with Visitor Counter Page 8
PART (COMPONENTS) LIST Automatic Room Light Controller with Visitor Counter-K682
Main Board – PCB 1
R1 ~ R8 - 220E [RED, RED, BROWN] (8 NOS)
R9 ~ 15 - 10K [BROWN, BLACK, ORANGE] (7 NOS)
R16 - 1K [BROWN, BLACK, RED]
C1 - 10UF / 25V Electrolytic
C2, 3 - 33PF Ceramic Disc (2 NOS)
C4 - 220UF / 16V Electrolytic
C5, 6 - 100KPF DISC (0.1UF / 104) (2 NOS)
X1 - 11.0592 MHZ Crystal
D1, 2 - IN4007 Diode (2 NOS)
L1 - 3 mm / 5 mm LED
Q1 ~ Q4 - BC557 / BC558 (PNP TRANSISTOR) (4 NOS)
Q5 - BC547 / BC548 (NPN TRANSISTOR)
U1 - AT89C2051 MICROCONTROLLER (Pre Programmed MCU)
U2 - LM7805 - 3 Pin Voltage Regulator
DS1 ~ DS4 - LT542 / A5611 (4 NOS)
COMMEN ANOD SEVEN SEGMENT LED DISPLAY
RLY - 12V SPDT PCB Mount Relay
1 nos - 20 PIN IC SOCKET
CN3 - 3 PIN TERMINALS BLOCK (not include in the kit)
CN2 - 2 PIN TERMINALS BLOCK (not include in the kit)
Sensor Board – PCB 2
R1, 2 - 220E [RED, RED, BROWN] (2 NOS)
R3, 4, 5, 6 - 10K [BROWN, BLACK, ORANGE] (4 NOS)
R7, 8 - 1K [BROWN, BLACK, RED] (2 NOS)
PR1, 2 - 10K CERMET – PRESET (2 NOS)
L1, 2 - 3 mm / 5 mm LED (2 NOS)
IR1, 2 - 5mm IR LED (Infrared Transmitter) (2 NOS)
PT1, 2 - 5mm Black IR Photo diode (Infrared Receiver) (2 NOS)
U1 - LM358 Dual Operational Amplifier
1 nos - 8 PIN IC SOCKET