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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_battery8/3/2019 10 Operatn
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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)Top Related