Stepper Motor Interfacing With 8051 Microcontroller

A stepper motor is a brushless and synchronous motor,which divides the complete rotation into number of steps.Each stepper motor will have some fixed step angle and motor rotates at this angle.Stepper motor is widely used in industrial,medicals,consumer electronics application.

The total rotation of the stepper motor is divided into steps.The step is known as the stepper angle of the motor.There are two types of stepper motors Unipolar and Bipolar. Mostly the Unipolar is commonly used by electronics field.

Stepper Motor Comparison With DC Motor

The DC motors,the current consumption of the stepper motors does not depend upon the load.Upon no load they still draw much current.In this Way,They get hot and lowers on their efficiency.In stepper motors there is smaller torque at high speeds than at low speeds.But mostly these stepper motors are used in high speed routine.For obtaining that high speed performance they need to be paired with a proper driver.

Unipolar Motor:

Only one winding with center tape per phase.
Each winding section is switched on for each direction of magnetic field
Centre tap of each winding is made common

Bipolar Motor :

Only single winding per phase
Current in winding must be reversed to reverse a magnetic pole
Two leads per phase,none are common

Advantage of Stepper Motor:

Low Cost
High Reliability
Good Performance in starting,stopping and reversing the direction
High torque at low speed
Gravel construction (can be used in variable environment)

Project Description:

Wave Drive: Only one electromagnet is energized at a time,generated torque will be less when compared to full drive in which two electromagnets are energized at a time but power consumption is reduced.This drive power consumption is more important than torque.So it is rarely used.
Full Drive: Full Drive-Two electromagnets are energized at a time,so the torque is generated will be larger when compared to the Wave Drive.Power consumption will be higher than the other modes.
Half Drive : One and Two electromagnets are energized,so it is a combination of Wave and Full drives.This mode is commonly used to increase the angular resolution of the motor but the torque will be less,about 70% at its half step position.

Project Implementation:

The circuit consist of 8051 Microcontroller,ULN2003A,Stepper Motor.AT89C51 is low power,high performance,CMOS 8 bit, 8051 family mocrocontroller.it has 32 programmable I/O lines.It has 4k bytes of Flash programmable and erasable memory.An external crystal oscillator value is 12Mhz actual mention as 11.0592Mhz.The motor is connected to the Port 2 of the microcontroller through a driver IC.

The ULN2003A is current driver IC,is used to drive the current of the stepper motor as it requires more than 60 mA of current.It consists of seven Darlington arrays with common emitter.The IC consists of 16 pins in these 7 as outputs 7 are inputs pins used to the connect the microcontroller .Here 4 pins are connected to the microcontroller and the first 4 pins output is connected to the stepper motor.

Basically stepper motor has 6 pins terminal ,2 is for vcc and ground,the remaining four pins are connected to output of the stepper motor.

Software requirements:

Keil Uvision 3: Keil Software makes C compilers, macro assemblers, real-time kernels, debuggers, simulators, integrated environments and evaluation boards for the 8051, 251, ARM and XC16x/C16x/ST10 microcontroller families
Programming language: Embedded C language

Kit required to develop Stepper Motor Interfacing With 8051 Microcontroller:

Technologies you will learn by working on Stepper Motor Interfacing With 8051 Microcontroller:

Stepper Motor