Stepper motors are classified based on their windings and stepping sequence. There are two main types: permanent magnet stepper motors which use permanent magnets and electromagnetic fields, and variable reluctance stepper motors which have no permanent magnets. Stepper motors operate by energizing windings in a sequence to rotate the motor a number of steps. To interface and control a stepper motor, a microcontroller can be used to supply voltage signals to the motor windings in a programmed sequence to rotate the motor.

1. Interfacing Stepper motor

2. Introduction Stepper motor is different for ordinary motors It has named before the operation and structure of the motor. Yes,ofcourse the motor runs in steps and has many winding types Motor was classified into two types in both categories

3. Classification Based on windings permanent-magnet (PM) stepper motors, variable-reluctance (VR) stepper motors, hybrid stepper motors Based on steps 4 – steps 8 – steps

4. permanent-magnet stepper motor The permanent-magnet stepper motor operates on the reaction between a permanent-magnet rotor and an electromagnetic field. A basic two-pole PM stepper motor Variable-reluctance Stepper Motors The variable-reluctance (VR) stepper motor differs from the PM stepper in that it has no permanent-magnet rotor and no residual torque to hold the rotor at one position when turned off.

5. Permanent-magnet (PM) Stepper Motors (a)PM stepper motor; (b) 90 step; (c) 45 step.

6. Variable-reluctance stepper motor and switching sequence.

7. A 4 – step stepper motor

8. Connection of 4 – step stepper motor

9. Basic concept If you give supply to the windings, they started to get magnetized, and “the same poles repelled each other and opposite poles attract each other” concept is applicable for magnetized coil and inner magnetic shaft The shaft started to move to the portion where there is no magnetic force to free itself. At this position if the voltage applied to the coil changes continuously, motor also starts to rotate continuously.

10. Programming concept Start from the beginning , we are going to give some 4 binary values from either microcontroller or PC. As we know what to do for giving values form microcontroller, we can assign a char to give that value to particular port by using sfr. That is it, value passed to motor and the motor rotates………

11. Program structure #include<reg51.h> Sfr motordata=0x90; // Port 1 for motor interface Sbit control =P2^1; // controlling the motor Void main() { Control=1; motordata=0; While(1) { If(control==1) { motordata=0x88;

12. Program structure contd. motordata =0x44; motordata=0x22; motordata=0x11; } else { motordata=0x88; motordata =0x11; motordata=0x22; motordata=0x44; } } }

13. Assignment for next class Rotate a particular degree in motor Rotate the motor 45* both clockwise and anticlockwise continuously. Calculate the number of steps required for full rotation.