ELEC2042 Minor Project

Three Floor Lift

We have seen a lift that moves between two floors in lectures.

We will now extend this to three floors.

Your lift, and the state machine, will start on floor zero. The 10 available flip flops will all be reset

to zero on start.

When a floor button is pressed the corresponding input changes to 1. When the button is released

the corresponding input will change back to 0. When a floor is signalled your lift should start to

move to that floor. As the lift moves if the button for the current floor has been pressed then the lift

should stop at that floor.

Your lift should implement an elevator algorithm, that means that it continues moving in the current

direction until it reaches the last floor requested in that direction. It should not reverse direction

without stopping at all floors (either up or down) that were requested.

In a practical sense it means if the lift is currently at floor 0 and buttons 1 and 2 are pressed it will

start to move upwards. If when moving, but before floor 1 is reached, button 0 is pressed the lift

should only move back towards floor 0 after floor 2 has been reached.

The lift optionally has doors. This is signified by setting the Has_Doors output to 1. If set to 1 this

output must remain as 1, it is a fault if this output changes from 1 to 0. Your lift controller can

request the doors be opened by setting the Open/Close output to 1. When that output is 0 the doors

will close. The Door_State input will identify the current state of the doors.

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Three Floor Lift

Minor Project v1/nYou are to produce a PDF document that describes your project, and the equations that will

implement your lift controller.

The PDF document details each of the following elements:

1

A high level summary of your design. In this summary you will describe the thinking that

was behind your design, and why you have the elements you do in your design. This design

is a conceptual description of your solution. You will need to create a Moore design for your

system.

2. The state transition diagram. This will hold each state the system is in, and what causes a

transition between those states.

3. Details of the memory elements utilised in your design, as well as the different

combinatorial circuits.

• It is possible, and required, that this design can be accomplished with less than 11 D flip

flops as the memory elements. These can be called: DO, D1, D2, up to D9as the D inputs to

each, and Qo, Q1, Q2, up to Q9as the outputs of each D flip flop.

4. A state transition table detailing the inputs and outputs of the combinatorial circuit

components.

• The inputs will be Floor_0, Floor_1, Floor 2, Button_0, Button_1, Button_2,

Door_State as well as the current state Qs (Q0, Q1, Q2... Q9).

• The outputs will be D0, D1, D2... D9 (the next state), Has_Doors, Open/Close,

Up/Down, as well as Move/Stop.

5. Karnaugh Maps for your combinatorial circuits.

• You will need to use a don't care techniques to simplify the Karnaugh maps so they can

be completed by hand.

6. Minimal Sum of Products equations for your Kamaugh Maps.

• For the minimum SoPs you will also enter these in a special submission box which will

be automatically graded.

The equations for the Minimal Sum of Products will be entered into a quiz on iLeam. These

equations will be graded using a lift simulator to ensure your lift operates correctly. The functioning

of your lift will dictate the grade level of your assignment.

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Three Floor Lift

Minor Project v1/nThe Inputs, and their means are detailed below:

Input

Floor_0

Floor 1

Floor_2

Button 0

Button_1

Button_2

Door_State[0:1]

The Outputs, and their required meanings are detailed below:

Meaning

The lift will move when 1, or be stationary when 0

The lift motor should move up when 1, or down when 0

The doors should open when 1, and close when 0

When 1 the lift has doors, when 0 door inputs and outputs

are ignored

Output

Move/Stop

Up/Down

Open/Close

Has_Doors

Meaning (When 1)

The lift is registered as present at floor 0

The lift is registered as present at floor 1

The lift is registered as present at floor 2

The request button has been pressed for floor 0

The request button has been pressed for floor 1

The request button has been pressed for floor 2

The doors are closed [00], opening[01], open [11] and

closing[10]

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Three Floor Lift

Minor Project v1/nGrading will consist of a series of tests on the equations. The document may be examined for

additional detail if questions arise from the running of the equations. Your equations will be run in a

simulator and your lift will be given a set of inputs. The outputs will be examined to verify the lift

performs as it is supposed to perform.

For a HD grade the door functions must be implemented. However, if your code asserts Has_Doors,

and the doors don't function then the highest grade you can obtain will be credit.

You will be awarded the LOWEST grade for which you qualify:

Grade

Fail

Pass

Credit

Minimal Solution with all elements of the document present, some problems with

overview of the solution, incorrect justification of the solution chosen, SoP are not

minimal, Lift equations move between all three floors in perfect cases, but some

errors in other test cases. Asserts Has_Doors and doors do not fully function.

Distinction Solution that works and adequate justification, mapping between state diagram and

state transition table is unclear. The lift passes all non-door tests and does not pass

all door tests.

Reasons for awarding this grade (OR list)

No submission, submission is not readable, submission does not answer the criteria.

Minimal Solution, some faults are present, some elements of the solution are

missing, Karnaugh Maps are not present.

High

Distinction

Solution that works with a complete and detailed justification and all elements

required are complete. The lift functions and doors open/close. Also, the machine

tests all pass.

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Three Floor Lift

Minor Project v1