OBJECTIVE:  In this lab, the student will interface a stepper motor to the driver outputs of the Stanton trainer.  Each output is driven by a Darlington transistor pair and will sink 200 mA.  The Darlingtons are driven by the 8255 on the Stanton board.  The student will connect the stepper motor and write a program to exercise the stepper motor.

EQUIPMENT NECESSARY:
 

Stanton Board

Stepper Motor

PER-LAB:
1.  Write a menu program to do the following:

- Turn the stepper motor the number of degrees entered at a prompt.  The motor will turn the specified number of degrees, stop for 1 second, turn, stop, etc., until a key is pressed.  Important information: the motor has four phases, and the basic step size is 3.6 degrees.  Also, because of the response time limitations of the motor, a delay interval of 50 ms (use the C function delay(time<ms>).  There are four outputs on the Stanton board labeled Stepper Motor Connection.  These are controlled by sending values to PC0 to PC3 of the 8255 inside the Stanton.  (This 8255 uses port addresses 31C-31F.)  Activate the motor control pins in the following order: 0,1,2,3.  The four pins from the Stanton board should be connected to white, red, green, and brown leads, respectively, of the motor.  In addition, the black wire from the motor should be connected to the +12 volt line from the breadboard.

- Then turn the motor a (new) prompted number of revolutions in a manner similar to the above (rotate the specified number of revolutions, delay for one second, rotate again, delay one second, etc.)  Do this until another key is pressed.

- Then turn the motor continuously, at a prompted RPM rate.  Again, use the C statement delay(ms) for the timing control.  The stepper motor has a "speed limit" - a maximum RPM rate it can achieve from a dead start.  The motor can go higher than this speed by starting at a lower speed and ramping up to the desired speed.  The motors in the lab have a limit from 250-300 RPM (determined in past labs).

-  The program should have a menu for selecting different program components.

POST-LAB:
1.  Write a report.  Discuss possible applications for a stepper motor.  How would one measure the RPM directly from the shaft?