1. Interfacing of stepper motor

2. Stepper motor
A stepper motor (or step motor) is a brushless DC electric motor that divides a full rotation into a number of equal steps.
The motor's position can then be commanded to move and hold at one of these steps without any feedback sensor (an open-loop controller), as long as the motor is carefully sized to the application.

3. Interfacing of stepper motor:-

4. There are two possible modes:-
Mode 1(Full stepping):-
Stepping motors have 200 rotor teeth, or 200 full steps per revolution of the motor shaft. Dividing the 200 steps into the 360º of rotation equals a 1.8º full step angle
2. Mode 2(Half stepping):-
Half step simply means that the step motor is rotating at 400 steps per revolution. In this mode, one winding is energized and then two windings are energized alternately, causing the rotor to rotate at half the distance, or 0.9º.

5. In mode1(Full stepping) ,the motor moves by 1
In mode1(Full stepping) ,the motor moves by 1.8°, to do this two bits are changed at a time ,the bit pattern is as A B C D 1 05 09 0A 06
Forward
Reverse

6. Program for full stepping
MVI A,80H OUT 03H BACK:LXI H,2000H MVI C,04H UP: MOV A,M OUT 00H CALL DELAY INX H DCR C JNZ UP JMP BACK
Address
Data
2000 05
2001 09
2002 0A
2003 06

9. In mode 2(half stepping) ,the motor moves by 0
In mode 2(half stepping) ,the motor moves by 0.9° to do this 1 bit is changed at a time and the bit pattern is as:- A B C D 1 0A 08 09 01 05 04 06 02
Reverse
Forward

10. Program for half stepping
MVI A,80H OUT 03H BACK: LXI H,2000H MVI C,08H UP: MOV A,M OUT 00H CALL DELAY INX H DCR C JNZ UP JMP BACK
Address
Data
2000 0A
2001 08 09
2002 01
2003 05
2004 04
2005 06
2006 02