Slide 1

PROCESSOR UNIT

Microprocessor is widely used processer unit for processing the large set of data and instruction given by user. It has only the CPU unit and require external RAM, ROM, I/O and other peripheral. To perform the small set of specific function, Microprocessor is a expensive and bulkier cercuit.

To overcome the problem, we use a low cost and simpler circuit chip, called Microcontroller.

Microcontroller is a mini computer on a single integrated circuit chip containing a processor core, memory and programmable input/output peripherals.

MICROPROCESSER AND MICRO CONTROLLER

Microcontroller 8051 has 4K ROM(code memory) and 128 byte RAM, two timer/counter, 4 general purpose input/out port and interrupt control logic with 5 sourse.

PROJECT INTRODUCTION In the project a microcontroller based unipolar stepper motor used to creat a four stroke linear positioning system, this system can move up and down, along with the floor. The opening and closing of this linear stroke positioning doors are displayed on the green and red LEDs respectively.

The positioning is controlled by four micro- switches.

The control program is developed in C language and converted into executable or in HEX language by AVR-GCC compiler.

LIST OF COMPONENTS REQUIRED FULL WAVE BRIDGE RECTIFIER WITH 4 IN 4001DIODES, 220/12V TRANSFORMER(SINGLE PHASE) AND 1000UF CAPACITOR. LM7805 VOLTAGE RAGULATOR.

89C51 MICROCONTROLLER.

UNIPOLAR STEPPER MOTOR.

ULN2003 STEPPER MOTOR DRIVER.

LCD(16*2) TWO ORDINARY LEDS (GREEN AND RED)

STEPPER MOTER Stepper moter is a microcontroler controlled DC moter that can rotate in both direction and having a holding torque at zero speed.

Stepper motors are rated with a varying degree of inductance.

A high inductance motor will provide a greater amount of torque at low speeds and lower torque at high speeds.

Stepper motor is designed to run hot between the ranges of 50-90 degree.

8

On the bases of wire arrangement stepper motor are categorized into two types- 1. Unipolar stepper motor 2. Bipolar stepper motor.

Center taps are present Center taps are not present so have two winding/phase so Have single winding/phase Less efficient because of More efficient(50% more 50% utilization of wire. then unipolar)Provide Low torque High torque & great power

Why we Prefer Unipolar Stepper Motor instead of Bipolar Stepper Motor-

In Bipolar Stepper Motor we require a H-bridge complicated driver circuit to reverse the current direction in winding, which is costely and motor efficiency decreases. But Unipolar Stepper Motor has two windings per phase, one for each direction of magnetic field, so in this arrangement a magnetic pole can be reversed without reverse the direction of current.

Unipolar Stepper Motor can be control using bipolar method by removing the connection of the common wires but reverse is not possibal.

STEPPER MOTER WITH MICROCONTROLLER

Stepper motors with microcontrollers are used in numerous applications when there is need of controlling the motion. The microcontroller is used to controls the speed as well as position of stepper motor. The speed of stepper motor is directly proportional to the frequency of drive input pluses which is controllable with the help of microcontrollers and the rotation is proportional to the number of output pulses.

The speed of stepper motor is controlled by changing the delay time of pulses and control over position is done by the number of pulses.

STEPPER MOTOR DRIVER Microcontroller output pulse is not sufficient to drive the stepper motor, stepper motors coil need arround 10mA to energize but the microcontrollers pin can provide a maximum of 1-2mA current, so we use a driver cercuit to operate the stepper motor.

Driver cercuit is basically a current amplifier, that receive low level signals from the controller and convert them into electrical pulses to run the motor. TYPES OF STEPPER MOTOR DRIVER-

R/L DRIVER BIPOLAR DRIVER UNIPOLAR DRIVER

RESISTANCE LIMITED DRIVER The drives are too old as compared to the drivers technology. They only exist in some application because they are simple and inexpensive.

BIPOLAR DRIVERThese driver used in bipolar stepper motor for industrial purpose applications. These drives are more expensive but they offer high performance and efficiency.

UNIPOLAR DRIVER CERCUIT ( ULN2003A ) It is used to drive unipolar stepper motor.

Phase winding of motor have large inductance, therefore in series in each phase winding a resistance is inserted to reduce the circuit time constant. A resistance is also placed in series with the diode in order to dissipate the energy stored in the phase winding inductance.

FULL WAVE BRIDGE RECTIFIER

Full wave bridge rectifier is used to convert the ac supply into dc supply. For this purpose four IN 4001 general purpose diodes is used in bridge configuration. An electrolytic capacitor of 1000 microfarad is connected parallel with these diodes to filter-out the harmonics present in the DC output supply.

LM7805 VOLTAGE REGULATOR

LM7805 voltage regulator is used to generating output current of 1A and for changing 12V DC to 5DC. It provides thermal overload protection and short circuit protection to the connected device. LM7805 have lower power consumption and provides better voltage regulation to the connected system.

LIQUID CRYSTAL DISPLAY (LCD)

A LCD(liquid crystal display) is specifically menufactured to be used with microcontroller, it cannot be activated by standard IC cercuit.

It is used for displaying different massages on a liquid crystal display.

It display all the letters of alphabet, mathematic symbols, Greek letters etc. In addition, it is possible to display symbols made up by the user.

Other usel features are automatic massage sift(left to right) and cursor appearance.

PROJECT DISCRIPTION

The design project is divided into four step of equal distance step.The stepper motor is connected to the 4 stroke linear lifting pulley with belt.The stepper motor pulley will took 40full rotations to lift the 4stroke linear positioning to cover the distance from one step to another.The LCD display the real time information about the 4 stroke linear positioning.At desired location green LED glow which represent the opening of 4 stroke linear positioning door and after five sec delay green LED off and red LED glow which represents the closing of 4 stroke linear positioning door.

Stepper motor covers 7.5 degree rotation in one step so we fix 40 such full rotation that moves this motor to one desired floor .

No. of steps are given by microcontroller to the stepper motor driver. For each floor position we have fixed a micro-switch.

When we press switch for first floor 40 rotations are selected by controller and we reach to desired floor and if we want to go to second floor we select second switch which provide 80 full rotation of stepper motor and so on.