1.Introduction:

Automatic multistoried car parking system helps to minimize the car parking area. In the modern world, where parking-space has become a very big problem and in the era of miniaturization, it is become a very crucial necessity to avoid the wastage of space in modern, big companies and apartments etc. In places where more than 100 cars need to be parked, this system proves to be useful in reducing wastage of space. This Automatic Car Parking System enables the parking of vehicles, floor after floor and thus reducing the space used. Here any number of cars can be parked according to the requirement. This makes the system modernized and even a space-saving one. This idea is developed using 8051 Microcontroller. Here program is written according to this idea using 8051.

2. Basic idea:

A display is provided at the ground floor which is basically a counter that displays number of cars in each floor. It informs whether the floors are fully filled with the cars or is it having place in a particular floor or not. There is facility of lift to carry the car to up and down. Movement of Lift is controlled by stepper motor. An indicator with a green and red LED is kept in all the floors to indicate whether the lift is busy or is it ready to take the car up or down. If the red LED glows that means the lift is already engaged and the person has to wait for the green LED to glow. In this project we have provided three floors of a building for car parking. Maximum storage capacity of each floor is given as ten. Storage capacity can be changed according to the requirement.

Any one can enter to first or second floor. The third floor in this model is for VIP’s only. Therefore when VIP’s are to be entering they are expected to enter their password and they will be taken to the third reserved floor. The password will be of 4 digits. The processor checks for the password entered and if it is found to be wrong, a siren is heard. In this particular model 10 passwords are stored. So when a password is entered, the processor checks for it and it is compared with 10 passwords. It indicates whether it is the correct one or not.

When the car enters the lift, the LDR detects its presence and sends a signal to glow RED LED indicating that the lift is busy. It also sends a signal to motor which makes the motor to rotate. After RED LED glows the lift will take the person and the car up to the floor where the space for parking is available. (For VIP it will be the third floor). When the lift reaches the first floor, the processor compares  the filled amount to that of the already fed capacity of that floor, and if it finds that the first floor is fully filled , it goes to the second floor and thus the procedure stops here. As soon as a car is placed in a particular floor, the display counter at the ground floor increments as to indicate the floor capacity has decreased by one. After the lift places the car in a particular floor, it comes back to its normal position and that time, the motor that drives it , also stops. Now processor sends signal to glow GREEN LED indicating that lift is free.

When a person needs to come down from a particular floor to ground floor, he is expected to focus the headlight onto the LDR placed in that floor. Now sensor section sends signal to motor that the lift has to be send back to that particular floor and sends a signal to glow RED LED indicating that the lift is busy. As soon as the lift reaches that particular floor car should come inside the lift, the display counter at the ground floor decrements by one as to indicate the floor capacity has increased by one. Lift comes back to its normal position and that time, the motor that drives it, also stops. Now processor sends signal to glow GREEN LED indicating that lift is free.

If there no parking taking place, the processor carries out the job according to the following priority:-

1. It checks whether any password is entered.
2. It checks whether any car is entered to lift.
3. It checks whether any car headlight is pressed in front of  LDR placed in each floor.

It is like a round robin system.

3. Hardware description:

Introduction to 8051 Microcontroller:

The first task faced when learning to use a new computer is to become familiar with the capability of the machine. The features of the computer best learned by studying the internal hardware design, also called the architecture of the device, to determine the type, number, and size of the registers and other circuitry.

The hardware is manipulated by an accompanying set of program instructions, or software. One familiar with hardware and software, the system designer can then apply the microcontroller to the problems at hand. In this project we make use of microcontroller.

The 8051 microcontroller generic part number actually includes a whole family of microcontrollers that have numbers ranging from 8031 to 8751.The block diagram of the 8051 shows all of the features unique to microcontrollers:

1. Internal ROM and RAM
2. I/O ports with programmable pins
3. Timers and counters
4. Serial data communication

The block diagram also shows the usual CPU components program counter, ALU, working registers, and the clock circuits.

The 8051 architecture consists of these specific features:

1. 8 bit CPU with registers A and B
2. 16 bit PC &data pointer (DPTR)
3. 8 bit program status word (PSW)
4. 8 bit stack pointer(SP)
5. Internal ROM or EPROM (8751)of 0(8031)to 4k(8051)
6. Internal RAM of 128 bytes.
7. 4 register banks , each containing 8 registers
8. 80 bits of general purpose data memory
9. 32 input/output pins arranged as four 8 bit ports:P0-P3
10. Two 16 bit timer/counters:T0-T1
11. Two external and three internal interrupt sources
12. Oscillator and clock circuits

A pin out of the 8051 packaged in a 40 pin DIP is shown below.

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Unlike the IC testers available in the market today which are usually expensive, this IC tester is affordable and user-friendly. This IC tester is constructed using 8951 microcontroller along with a keyboard and a display unit. It can test digital ICs having a maximum of 24 pins. Since it is programmable, any number of ICs can be tested within the constraint of the memory available. This IC tester can be used to test a wide variety of ICs which includes simple logic gates and also sequential and combinational ICs like flip-flops, counters, shift registers etc. It is portable and easy to use.

The block diagram of the programmable digital IC tester is as shown in below. It consists of two 8951 microcontroller ICs, a 24-pin IC socket, a keyboard unit, a display unit and indicators.

To test a particular digital IC, one needs to insert the IC into the IC socket and enter the IC number using the keyboard and then press the “ENTER” key. The IC number gets displayed in the 7-segment display unit.

Four LEDs are provided as indicators. If the IC being tested is a logic gate, then each of the 4 indicator LEDs correspond to the 4 gates of the IC. In any other case wherein the inserted IC is not a logic gate, all the 4 LEDs work as a single indicator.

Block diagram of Programmable Digital IC Tester:

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Introduction to Programmable number lock system:

The system has three units, namely:

1. Keyboard unit.
2. Display unit.
3. Control unit.

The keyboard unit consists of 9 number keys, 1 unlock key and 1 lock key. These are all push button switches. This unit is used to select the desired device and to enter the codes into the system. It is also used to request the system to lock/unlock the selected device.

The display section contains 5 seven segment display. This unit displays the device number and the code entered. This section is detachable. If detached it does not affect the working of the whole system. This unit also contains password reset button and an LED to indicate the error when the device is   already locked and user wants to lock the device again. The error indicator also indicates an error when the system is already unlocked and the user tries to unlock the same.

The control unit  is the heart of our system. It contains the necessary circuitry for the control of the device .This unit controls 9 devices, which is lock/unlock  by selecting it using the keyboard and entering the password. If the code entered to unlock the device is wrong, then a silent alarm is triggered .The keyboard unit and the display unit are connected to this unit.

All these three units are merged together to form the whole system.

Block diagram of Programmable number lock system:

Working of the system:

When the system  is initially installed the reset button is pressed. This key is present in the control unit. This unlocks all the devices. This is to avoid undesired functioning of the system.

To lock a particular device the device number is selected using the keyboard. Once the device is selected the user has to press the lock key present in the keyboard. Now the device waits for the user to enter the the code. The user can enter a 4 digit number using the keyboard as per his desire. Once all the 4 digits are entered the system electronically locks the selected device.

In the same manner to unlock a particular device, the device number is entered using the keyboard. Once the device number is selected the code for the selected device is entered. If the entered code matches the code that had been entered while that particular device was locked then the selected device will be activated (unlocked). If the codes do not match each other a silent alarm will be triggered (a LED placed in the control section. Shown in figure 3).An error indicator (placed in the display section) is provided if any user tries to lock a device which has already been locked or vice versa.

If the user is half way entering the code or has done an error while entering the code and wants to start over all again then a reset button is provided in the display section. By pressing this button the user can start from entering the device number and so on.

The number of devices which the system can control can be increased by addition of a few components in the control unit. More security can be achieved by increasing the number of digits in the code. This can be done by minor changes in the program. The system uses the internal RAM of the 8051 to store the code and hence puts a lower limit to the number of digits in the code and also the number of devices the system can control. Once the system is installed only the display unit and keyboard unit will be accessible to the user. Access to the control unit should be provided only to an official personal since it contains the system  reset button.

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General description and system block diagram:-

The complete board consists of transformer, control circuit, keypad and stepper motor as shown in snap. The given figure shows the block diagram of project.

The circuit has inbuilt 5 V power supply so when it is connected with transformer it will give the supply to circuit and motor both. The 8 Key keypad is connected with circuit through which user can give the command to control stepper motor. The control circuit includes micro controller 89C51, indicating LEDs, and current driver chip ULN2003A. One can program the controller to control the operation of stepper motor. He can give different commands through keypad like, run clockwise, run anticlockwise, increase/decrease RPM, increase/decrease revolutions, stop motor, change the mode, etc. before we start with project it is must that we first understood the operation of unipolar stepper motor.

Unipolar stepper motor:-

In the construction of unipolar stepper motor there are four coils. One end of each coil is tide together and it gives common terminal which is always connected with positive terminal of supply. The other ends of each coil are given for interface.  Specific color code may also be given. Like in my motor orange is first coil (L1), brown is second (L2), yellow is third (L3), black is fourth (L4) and red for common terminal.

By means of controlling a stepper motor operation we can

1. Increase or decrease the RPM (speed) of it
2. Increase or decrease number of revolutions of it
3. Change its direction means rotate it clockwise or anticlockwise

To vary the RPM of motor we have to vary the PRF (Pulse Repetition Frequency). Number of applied pulses will vary number of rotations and last to change direction we have to change pulse sequence.

So all these three things just depends on applied pulses. Now there are three different modes to rotate this motor

1. Single coil excitation
2. Double coil excitation
3. Half step excitation

The table given below will give you the complete idea that how to give pulses in each mode

Note:- In half step excitation mode motor will rotate at half the specified given step resolution. Means if step resolution is 1.8 degree then in this mode it will be 0.9 degree. Step resolution means on receiving on 1 pulse motor will rotate that much degree. If step resolution is 1.8 degree then it will take 200 pulses for motor to compete 1 revolution (360 degree).

Now let me give you the specification of the stepper motor that I have used.

Max rated voltage: –    5 V
Max rated current per coil: – 0.5 Amp
Step resolution: –    1.8 degree / pulse
Max RPM: –    20 in single/double coil excitation mode and 60 in half step mode
Torque: – 1.5 Kg/cm2

RPM calculation:-

One can calculate the exact RPM at which motor will run. We know that motor needs 200 pulses to complete 1 revolution. Means if 200 pulses applied in 1 second motor will complete 1 revolution in 1 second. Now 1 rev. in 1 sec means 60 rev. in 1 minute. That will give us 60 RPM. Now 200 pulses in 1 sec means the PRF is 200 Hz. And delay will be 5 millisecond (ms). Now lets see it reverse.

*  If delay is 10 ms then PRF will be 100 Hz.
*  So 100 pulses will be given in 1 sec
*  Motor will complete 1 revolution in 2 second
*  So the RPM will be 30.

In same manner as you change delay the PRF will be changed and it will change RPM

Stepper motor control board circuit:-

The circuit consists of very few components. The major components are 7805, 89C51 and ULN2003A.

Connections:-

1. The transformer terminals are given to bridge rectifier to generate rectified DC.
2. It is filtered and given to regulator IC 7805 to generate 5 V pure DC. LED indicates supply is ON.
3. All the push button micro switches J1 to J8 are connected with port P1 as shown to form serial keyboard.
4. 12 MHz crystal is connected to oscillator terminals of 89C51 with two biasing capacitors.
5. All the LEDs are connected to port P0 as shown
6. Port P2 drives stepper motor through current driver chip ULN2003A.
7. The common terminal of motor is connected to Vcc and rest all four terminals are connected to port P2 pins in sequence through ULN chip.

Now by downloading different programs in to 89C51 we can control the operation of stepper motor. Let us see all different kind of program.

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