1. SPEED CHECKER TO DETECT RASH DRIVING ON HIGHWAYS
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2. Abstract
The system basically comprises two laser IR sensor pairs, which are installed oppositely on the highway.
This sensed speed is fed to the Microcontroller which displays the time taken by the vehicle in crossing the required distance from one pair to the other from and also the speed of the vehicle.
In case the vehicle speed crosses the limits a buzzer gives beeps to indicate that the vehicle has crossed the speed limit. A relay is also activated when any vehicle crosses the speed limit.

3. Block diagram

4. Hardware requirements
TRANSFORMER (230 – 12 V AC)
VOLTAGE REGULATOR (LM 7805)
RECTIFIER
FILTER
MICROCONTROLLER (AT89S52/AT89C51)
IR LEDs
PHOTODIODES
LCD
PIEZO-BUZZER
RELAY
BC547
LED
1N4007
RESISTORS
CAPACITORS

5. POWER SUPPLY 230 V AC 50 Hz 12V step down transformer Bridge rectifier
Filter(470µf)
5v Regulator
5V DC

6. Description of power supply
The circuit uses standard power supply comprising of a step-down transformer from 230v to 12v and 4 diodes forming a Bridge Rectifier that delivers pulsating dc which is then filtered by an electrolytic capacitor of about 470microf to 100microF.
The filtered dc being un regulated IC LM7805 is used to get 5v constant at its pin no 3 irrespective of input dc varying from 9v to 14v.
The regulated 5volts dc is further filtered by a small electrolytic capacitor of 10 micro f for any noise so generated by the circuit.
One LED is connected of this 5v point in series with a resistor of 330ohms to the ground i.e. negative voltage to indicate 5v power supply availability.

7. It is a smaller computer Has on-chip RAM, ROM, I/O ports...
MICROCONTROLLER
It is a smaller computer
Has on-chip RAM, ROM, I/O ports...
RAM
ROM
I/O Port
Timer
Serial COM Port
Microcontroller
CPU
A single chip

8. INTERNAL STRUCTURE OF A MICRO CONTROLLER-AT89S52/51
CPU
On-chip RAM
On-chip ROM for program code
4 I/O Ports
Timer 0
Serial Port
OSC
Interrupt Control
External interrupts
Timer 1
Timer/Counter
Bus Control
TxD RxD
P0 P1 P2 P3
Address/Data
Counter Inputs

9. Microcontroller(at89s52)
Compatible with MCS®-51 Products
8K Bytes of In-System Programmable (ISP) Flash Memory
Endurance: 10,000 Write/Erase Cycles
4.0V to 5.5V Operating Range
Fully Static Operation: 0 Hz to 33 MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Eight Interrupt Sources
Full Duplex UART Serial Channel
Interrupt Recovery from Power-down Mode
Watchdog Timer
Dual Data Pointer
Fast Programming Time

10. PIN DIAGRAM OF AT89S52

11. Photo diode
A photodiode is a type of photo detector capable of converting light into either current or voltage, depending upon the mode of operation.
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 fibre connection to allow light to reach the sensitive part of the device.

12. IR LED
An IR LED, also known as IR transmitter, is a special purpose LED that transmits infrared rays in the range of 760 nm wavelength.
Such LEDs are usually made of gallium arsenide or aluminum gallium arsenide. They, along with IR receivers, are commonly used as sensors.
The appearance is same as a common LED. Since the human eye cannot see the infrared radiations, it is not possible for a person to identify whether the IR LED is working or not, unlike a common LED.
To overcome this problem, the camera on a cell phone can be used. The camera can show us the IR rays being emanated from the IR LED in a circuit.

13. LIQUID CRYSTAL DISPLAY (LCD)
Most common LCDs connected to the microcontrollers are 16x2 and
20x2 displays.
This means 16 characters per line by 2 lines and 20 characters per line
by 2 lines, respectively.
The standard is referred to as HD44780U, which refers to the controller
chip which receives data from an external source (and communicates
directly with the LCD.

14. LCD BACKGROUND
If an 8-bit data bus is used the LCD will require 11 data lines
(3 control lines plus the 8 lines for the data bus)
The three control lines are referred to as EN, RS, and RW
EN=Enable (used to tell the LCD that you are sending it data)
RS=Register Select (When RS is low (0), data is treated as a command)
(When RS is High(1), data being sent is text data )
R/W=Read/Write (When RW is low (0), the data written to the LCD)
(When RW is High(1), the data reading to the LCD)

15. LED
LEDs are semiconductor devices are made out of silicon.When current passes through the LED, it emits photons as a byproduct. Normal light bulbs produce light by heating a metal filament until its white hot.
LEDs present many advantages over traditional light sources including lower energy consumption, longer lifetime, improved robustness, smaller size and faster switching

16. RELAY IT IS A ELECTRO MAGNETIC SWITCH
USED TO CONTROL THE ELECTRICAL DEVICES
COPPER CORE MAGNETIC FLUX PLAYS MAIN ROLE HERE

17. The relay's switch connections are usually labeled COM, NC and NO:
COM = Common, always connect to this; it is the moving part of the itch.
NC = Normally Closed, COM is connected to this when the relay coil is off.
NO = Normally Open, COM is connected to this when the relay coil is on

18. BUZZER
Piezo Buzzer
This buzzer is an piezo type audio signaling device, which has a piezo
element and a oscillating circuit inside which oscillates the piezo brass base
plate, which when given voltage difference produces sound of a predefined
frequency.
Features
These high reliability piezo buzzers are applicable to general electronics equipment.
Compact, pin terminal type Piezo buzzer with 4 KHz output.
Pin type terminal construction enables direct mounting onto printed circuit boards.

19. Soft ware requirements
Keil an ARM Company makes C compilers, macro assemblers, real- time kernels, debuggers, simulators, integrated environments, evaluation boards, and emulators for ARM7/ARM9/Cortex-M3, XC16x/C16x/ST10, 251, and 8051 MCU families.
Compilers are programs used to convert a High Level Language to object code. Desktop compilers produce an output object code for the underlying microprocessor, but not for other microprocessors.

20. i.e the programs written in one of the HLL like ‘C’ will compile the code to run on the system for a particular processor like x86 (underlying microprocessor in the computer).
For example compilers for Dos platform is different from the Compilers for Unix platform  So if one wants to define a compiler then compiler is a program that translates source code into object code.

21. BIBILOGRAPHY
The Microcontroller and Embedded systems” by Muhammad Ali Mazidi and Janice Gillispie Mazidi , Pearson Education.
ATMEL 89S52 Data Sheets.