ECE 1315 UMD Fall, 2008

Experiment 10: FSM Design and Interface with Stepper Motor

It is desired to design and implement a Finite State Machine that controls the motion of a bipolar stepper motor. The

controller will have three input variables, X, Y and Clock. The controller will have 4 output variables, Z3, Z2, Z1, Z0, one

for each wire of the Stepper. The inputs and outputs are specified below:

Inputs: X = {0, Motor Stopped (controller disabled); 1, Motor Active}

Y = {0, Motor Turns Clockwise; 1, Motor turns counter-clockwise}

Clock : Self explanatory (Pin 22 , set for 0.5 second pulses)

Outputs: Z3 – Red Wire; Z2 – Brown Wire; Z1 – Yellow Wire; Z0 – Orange Wire

Operation: If the stepper motor wires receive a current pulse in the order indicated, Red then Brown then Yellow then

Orange, the motor will rotate clockwise. Current pulses in the reverse order will produce counter-clockwise rotation. This is

summarized in the table below:

Y = 0, Forward Operation:	Y = 1, Reverse Operation:
Z3 Z2 Z1 Z0	Z3 Z2 Z1 Z0
1 0 0 0	0 0 0 1
0 1 0 0	0 0 1 0
0 0 1 0	0 1 0 0
0 0 0 1	1 0 0 0
Repeat	Repeat

TABLE 1: Output Patterns Required for Forward and Reverse Rotation

Design: Your design should incorporate at least four states for your FSM. Consider that the input variables, X and Y, will

just be wires that you connect to Ground (0) or Vcc (1). Also realize that the 74LS109 – Dual J-Kbar Flip Flop has Preset and

Clear inputs. These may be utilized to enable/disable the controller with the X input. Note that Table 1 above has only four

unique outputs and your controller need only count up through those states or count down through them, depending on the

status of the Y input.

Design Cost: You are required to implement your design on a maximum of 3 chips. Additional consideration may be given to the

Gate Cost of your design, based on the cost table from Lab 8 (Dr. Weber’s Lab 7), so be frugal!

For your report: Include a State Diagram, State Transition Table, J-Kbar Input Table and a Schematic of your implementation.

Demonstration: Demonstrate that your design and implementation work with a stepper motor supplied by the Lab Instructor.

Obtain a signature:

Instructor Signature/ Chips/Gate Cost: _______________________________________