BACKGROUD:

Hardware Lab 4: EEE 120 Design Project

Deliverables

You are to design TWO finite-state synchronous machines, one being a Moore design and the other being a Mealy design. Depending on the application you have to decide whether you have to synchronize the outputs of the Mealy machine or not. You can use either D flip flops or J-K flip flops for your designs. Mixing different types of flip flops with different trigger edge sensitivity is possible but not recommended. Note that two designs which differ by only the type of flip flop (e.g., J-K vs. D) or number of states (i.e., changing the type of FF or inserting more unnecessary states) is not considered conceptually different.

First, you will need to implement BOTH designs using Logisim and include these simulations into your lab report template. Second, you will need to build ONE design using the TTL parts you used in earlier lab work and report your findings on the lab report template. You can use any part that you have available, J-K or D flip flops. The 4-bit D Register (74LS175 with clock and reset already wired together for the four D flip flops) that you have not used before might come in handy for the design project, in case you have it.

Washing Machine Controller

The Clean Laundry Company (CLC) is interested in reducing the risk of personal injury to their customers while operating their washing machine. When a customer wants to open the machines door, the machine should stop and the drum (motor) should come to a standstill before the door is allowed to open. Otherwise, the customer might get injured. The company installed a switch that the customer activates to indicate they are requesting to open the door. But since the motor doesnt stop immediately, the company installed a sensor that senses the motors rotation. If this sensor indicates the motor has stopped, then the door is unlocked. Hence, the company installed an electromechanical lock on the door. This lock is controlled by the controller you will design.

The controller should do the following: Normally, the machine is on where the motor is rotating in the normal washing cycle and the door is locked. If, in the middle of the cycle, the customer activates the door switch because of a need to open the door, the controller should power off the electric current from the motor so that begins to stop. However, since it doesnt stop immediately, the lock should remain locked until the motor stops. In addition to customer safety issues, this time gives the customer the opportunity to deactivate the door switch in case they change their mind and want the machine to continue the cycle that was interrupted. However, once the rotation sensor gives a 0 signal indicating that the motor has stopped (whether this stopping is because the customer activated the door switch or, say, the washing cycle finished), the lock should unlock and the electric current should power off. At this point, no matter what the customer does, the lock should NEVER lock back again NOR should the motor rotate again. If the customer needs the motor to return to normal operation, they need to call the laundry attendant to reset the controller via a switch that the customer does not have access to.

Note that there are two inputs to your controller: the rotation sensor (R) and the door switch (S). Your controller has two outputs that control the washing machine: the electric power output (P) and the door lock output (L).

All information to complete this design may not be specified. Write down and report any assumptions that you make in your design.

Assumptions

Answers to (some) the following questions might be good candidates to being your assumptions:

Does your machine need/use an asynchronous reset?

If your system has more than one input, which one is what (on your state diagram)? (Also don't forget to name your input switches in your Logisim file. Graders might consider your Logisim files not working if you did not label your input switches: CLOCK, Reset....etc.).

Some motor breaks respond extremely fast. Can your design allow for the case where the motor stops immediately after the customer activates the door switch? If yes/no, how will your controller respond to that case?

Mention anything you want as long as it makes common sense and such that it does not make the problem trivial. For example do not say: "I'm assuming that the motor always stops immediately once the customer activates the door switch". This means that there is no need to have a rotation sensor. This over simplifies the problem which is not accepted.

The benefit of the assumptions task is for you to tell the grader: "These are the limitations and capabilities of the machine that I am building".

A good designing engineer should take all possible input combinations into consideration rather than assuming some of them will not happen. Do not assume that an input combination (for example the input 01) will not happen unless its occurrence is physically/practically illogical. At that case, mention that explicitly in your assumptions and justify it. Otherwise all input combinations need to be taken into consideration while writing your state diagram.

We don't want a large list of assumptions. 2-3 assumptions are enough.

You don't have to list the assumptions before finishing your design. You might need to modify it while designing your machine. That's nature of any design process. We recommend listing your assumptions after the diagram is complete.

Your assumptions for Design 2 could be the same as those for Design 1, but don't have to.

Check List

First step is to define the inputs and outputs of your design, as well as the values that each input and output might take.

Make sure you have included your assumptions for your project.

Make sure your state diagram is complete: no missing arrows/states/inputs/outputs.

Make sure your state diagram is readable: Which value mentioned on the arrow corresponds to which input.

Make sure to use a synchronization flip flop at the output of the Mealy machine. We will not penalize if you don't have it, but if you test your circuit without it, you need to know how to verify your circuit is working. It needs some experience.

In task 4-5, the clocks of the flip flops need to be connected to one of the DIOs. Some students connect them to a manual switch. If you have a manual switch, please don't use it to feed the clock.

When filling in the column of the output in the Moore transition table, you need to look at the present state not at the next state because in a Moore state transition table, the output depends on the present state and not the next state. This is a fact that applies to the Moore design and not to the Mealy design. Thus, if you found your output changes with the change in the input when you simulate your Moore circuit, then you have missed this fact.

Any state diagram should be complete: Each state has to have 2ⁿ arrows coming out of it where n is the number of inputs to the system. This is the case for both the Mealy and the Moore machine.

Don't forget to connect the PRE' and the CLR' of your chips to the Vcc while you build your hardware portion of this lab.

Do not build the FFs from scratch when simulating your design on Logisim. Use the FFs built-in already in Logisim. They are found under the Memory folder in the Logisim software.

Question with format desired:

Task 4-1: Design of Synchronous Sequential Machines

Design #1 (Mealy machine): What assumptions did you make in the design of this machine?________ ____________________________________________________________________________________

_____________________________________________________________________________________

Create a state definition table here that describes in plain English what each state in your machine means and what binary values you have assigned to represent each state.

Create tables here to display your state diagrams, state transition tables and Karnaugh maps used in your design process. (You can do this by hand if you wish.)

Include a picture of your Logisim design schematic #1 (Mealy machine) circuit here:

Design #2 (Moore machine): What assumptions did you make in the design of this machine? _____________________________________________________________________________________

_____________________________________________________________________________________

Create a state definition table here that describes in plain English what each state in your machine means and what binary values you have assigned to represent each state.

Create tables here to display your state diagrams, state transition tables and Karnaugh maps used in your design process. (You can do this by hand if you wish.)

Include a picture of your Logisim design schematic #2 (Moore machine) circuit here: