ELEC242 2019 Session 2

ELEC242 2019 Session 2

Assignment 1

This assignment is the simple design assignment. You are given a problem, need to create truth tables, Karnaugh maps and finally minimum Sum-Of-Products equations

You are designing the control system for a Minimum Viable Product lift. The lift has three floors, 0, 1 and 2. There are push buttons for each floor to summon the lift, and three buttons inside the lift to designate the desired destination floor for the lift.

Your submission must be typeset, Karnaugh maps can be produced as Tables, or spreadsheet matrices. NO hand drawn or scanned input will be graded.

Motor Control Outputs

Your control system needs to interface with the motor system for the lift. The motor system takes two bits of input, and follows the following truth table:

Motor

System

Input

Meaning

0

0

Stop

0

1

Move Down

1

0

Move Up

1

1

undefined

Floor Detection Inputs

The floor detection system provides you with information about the lift position. It has the following outputs:

Floor

Detection

Outputs

Meaning

0

0

At floor 0

0

1

At floor 1

1

0

At floor 2

1

1

Between floors

Human Interface Inputs

There are six input buttons: F0, F1, F2, L0, L1 and L2. They are the three floor buttons, one on each floor to summon the lift and the three buttons inside the lift. Each button goes high when the button is pressed and reverts back to low when the button is released.

Task

You are to design the state machine and combinatorial circuitry for the lift control system. Your state machine needs to keep track of the last floor the lift was on, the floors that need to be visited and the current direction of the lift.

The state is held in the following D flip flop groups:

Last floor visited (Two flip flops)

Next floor to visit (Two flip flops)

Current Direction (Two flip flops)

Floors that need to be visited (Three flip flops)

The meanings of the bits in these flip flops will be as follows:

Last Floor Meaning
0 0 Last at floor 0
0 1 Last at floor 1
1 0 Last at floor 2
1 1 Invalid
Next Floor Meaning
0 0 Moving to floor 0
0 1 Moving to floor 1
1 0 Moving to floor 2
1 1 Invalid
Direction Meaning
0 0 Stationary
0 1 Moving Down
1 0 Moving Up
1 1 Invalid
Floor Meaning
F0 F1 F2
1 X X Floor 0 to be visited

Questions

  1. Create truth tables for each of the D flip flop groups. You must include all necessary inputs to allow you to specify the change in state for each group.
  2. Create Karnaugh maps for each output (Flip flop) in the groups. There should be nine (9) Karnaugh maps devised
  3. From the Karnaugh maps create minimum Sum-Of-Products equations for your state machine. There should be one Sum-Of-Products equation for each D flip flop.

Submit your responses as a single typeset PDF file through the turnitin link on ilearn. Your submission must be typeset, Karnaugh maps can be produced as Tables, or spreadsheet matrices. NO hand drawn or scanned input will be graded. Your submission must include a faculty coversheet.