This is the circuit diagram of interfacing of half stepper motor with 8051.
Stepper motors consist of a permanent magnet rotating shaft, known as rotor, and electromagnets on the stationary portion that surrounds the motor, known as stator. You can see in the figure given below. In half stepping rotor moves with 45 degree. At position 1, we see that the rotor is beginning at the upper electromagnet, which is currently active because we have applied voltage. To move the rotor clockwise, the upper electromagnet is still activated and the right electromagnet is activated also, causing the rotor to move 45 degrees clockwise, aligning itself with the active magnet because both stator attracts rotor with same force. This process is repeated in the same manner at the south and west electromagnets until we once again reach the starting position.
