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RFID BASED AUTOMOBILE SECURITY SYSTEM

Circuit Operation

5.1 Introduction:

The total hardware and software description are discussed above which are more

helpful to understand the circuit operation. The circuit operation and utilization of the

microcontroller and also the interface connected as shown in Fig 5.1.1. The practical and

real time application circuits are explained with internal blocks of an automobile mainly

the starter solenoid of automobiles.

Figure 5.1.1 Block Diagram of Automobile Security System

4.2 Flow Charts and algorithm

Algorithm:Step 1: Power ON the supply 230v

Step 2: Press the reset button once

Step 3: LCD o/p message will be WELCOME TO RFID SECURITY SYSTEM

Step 4: Keep the respective tag towards the RFID reader

Step 5: If the tag code matches,

Step 6: LCD o/p display ACCESS GRANTED

Step 7: Relay/solenoid gets activated according to the system operation

Step 8: If the tag code doesnt matches,

Step 9: LCD displays as ACCESS DENIED ID

Step 10: Recheck the tag and try once again from step 4 after few seconds

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RFID BASED AUTOMOBILE SECURITY SYSTEM

Flow Chart:

NO

YES

Figure 4.3.2 Total operation of the circuit

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START

ON THE POWER

SUPPLY

Press the reset

Keep the card

towards the

reader

Display:

welcome to

RFID

If tag ID

Matches

Display:

Access

Relay/Soleno

id ONs with

Display:

Accessdenied ID

Re check

the Tag

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RFID BASED AUTOMOBILE SECURITY SYSTEM

5.2 Connections:

RFID Automobile Security System to derive the power supply, the 230V, 50Hz AC

mains is stepped down by transformer X1 to deliver a secondary output of 15V, 500mA.

The transformer output is rectified by a full-wave rectifier comprising diodes D1 throughD4, filtered by capacitor C1 and regulated by ICs 7812 (IC2) and 7805 (IC3). Capacitor

C2 bypasses the ripples present in the regulated supply. LED1 acts as the power indicator

and R2 limits the current through LED1. The compact circuitry is built around Atmel

AT89S52 microcontroller. The system clock also plays a significant role in operation of

the microcontroller.

An 11.0592MHz quartz crystal connected to pins 18 and 19 provides basic clock to the

microcontroller. Power-on reset is provided by the combination of electrolytic capacitor

C4 and resistor R1. Switch S1 is used for manual reset. Port pins P2.0 through P2.7 of the

microcontroller are connected to data port pins D0 through D7 of the LCD, respectively.

Port pins P3.7 and P3.6 of the microcontroller are connected to register-select (RS) and

enable (E) pins of the LCD, respectively. Read/write (R/W) pin of the LCD is grounded

to enable for write operation. Resistor R6 limits the current through the backlight of the

LCD. Port pins P3.0 (RXD) and P3.1 (TXD) of the microcontroller are used to interface

with the RFID reader. When power is removed the reverse voltage spike [back EMF

produced by the relay due to magnetic field discharge] is observed by the diode connected

parallel to the relay.

Figure 5.2.1 Circuit diagram of the Practical system

5.3 Operation:

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RFID BASED AUTOMOBILE SECURITY SYSTEM

CASE 1: When an authorized person having the tag enters the RF field generated by the

RFID reader, RF signal is generated by the RFID reader to transmit energy to the tag and

retrieve data from the tag. Then the RFID reader communicates through RXD and TXD

pins of the microcontroller for further processing. Thus on identifying the authorized

person, port pin P3.2 goes high, transistor T2 drives into saturation, provides ground tothe relay and relay RL1 energizes and activates. Simultaneously, the LCD shows access

granted ID message and port pin P1.7 drives piezo buzzer PZ1 via transistor T1 for aural

indication.

CASE 2:If the person is unauthorized, the LCD shows access denied ID and the relay

doesnt operate. So the circuit will not operates because the code of the RFID will not

match with the code embedded in the program of micro controller, there will be no

activation signal for T1 and T2

5.4 Practical Implementation:

The power RPS is replaced with the battery of the automobile and in the place of

Relay we take 12v solenoid of any automobile.

According to the figure our 12v input is given to the s terminal and ground to the T2

transistor of the circuit

Battery connection is taken from the battery and given to the battery terminal and the

starter connection is given to the starter terminal of the solenoid component which is

a part of the starter motor.

Figure 5.4.1 Real time application of the system

The circuit operates in the same way as it is operated when theres a relay

It continues with the same two conditions the operation of the solenoid in the starter

solenoid is explained here

When ignition key is pressed to the start position

12v signal will get to the ignition switch

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RFID BASED AUTOMOBILE SECURITY SYSTEM

Current from the s terminal reaches the ground through the winding of the solenoid

A magnetic field is created around that wire, this magnetic field den pushes the

plunger which also pushes the contact washer then makes the contact with the battery

and the starter within the solenoid

Figure 5.4.2 Practical solenoid working

Solenoid makes a high ampere current connection from the battery to starter[solenoid

is controlled by the low voltage signal(12v) ]

The starter solenoid receives a large electric current from the automobile battery and

a small electric current from the ignition switch [supply from the designed circuit].

When the ignition switch is turned on, a small electric current is sent to the starter

solenoid. This causes the starter solenoid to close a pair of heavy contacts, thus

relaying a large electric current to the starter motor, which in turn sets the engine in

motion.

Our circuit acts as a ignition signal given to the solenoid switch which exists the

connection between battery to the starter.

Starter solenoid is the main component used in this project which is used to activates

the vehicle and its total housing is shown in the figure 5.4.2

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http://en.wikipedia.org/wiki/Car_batteryhttp://en.wikipedia.org/wiki/Ignition_switchhttp://en.wikipedia.org/wiki/Ignition_switchhttp://en.wikipedia.org/wiki/Car_battery

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RFID BASED AUTOMOBILE SECURITY SYSTEM

Figure 5.4.3 Starter solenoid of the regular automobile

1. Main Housing (yoke) 2. Overrunning clutch

3. Armature 4. Field coils

5. Brushes 6. Solenoid

5.5 Summary

The main circuit operation is totally explained and main defaults of the circuit are

Circuit should be developed for high currents.

Programming should be developed so that the relay(solenoid) operates for some

more time to produce a connection between battery and starter so that vehicle gets

started

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http://en.wikipedia.org/wiki/Overrunning_clutchhttp://en.wikipedia.org/wiki/Armature_(electrical_engineering)http://en.wikipedia.org/wiki/Field_coilshttp://en.wikipedia.org/wiki/Brush_(electric)http://en.wikipedia.org/wiki/Overrunning_clutchhttp://en.wikipedia.org/wiki/Armature_(electrical_engineering)http://en.wikipedia.org/wiki/Field_coilshttp://en.wikipedia.org/wiki/Brush_(electric)