Designing Synchronous Machines

Hardware Lab 4: EEE/CSE 120 Design Project

Spring 2016


You are to design two CONCEPTUALLY different finite-state synchronous machines by

performing the tasks described for the Gas Pump Controller functional specification. (A design

which differs by only the type of flip flop (e.g., J-K vs. D) or number of states (i.e., inserting

more unnecessary states) is not considered conceptually different.

First, you will need to implement both designs using Logisim and demonstrate to the

CSE/EEE 120 simulation TA’s in GWC 185 that both designs work correctly by the

software due date (See Table 1 below). You will need to sign up on Doodle for a time slot at

which you will demonstrate your design to a TA in GWC 185. The link for your sessions is

the following: You may demo this by either 1)

opening your file using the computer reserved by the TA on duty or 2) asking the TA to test your

circuit on your laptop. You will need to bring with you a printout of your report template

into which you’ve cut/pasted your Logisim circuits. It makes most sense to complete the lab

template and print it before you go and demonstrate the designs to the TA. You must have your

design simulation working before asking the TA to test it because you will be given only

one chance to prove that it works. You must also be able to defend your design; the TA’s

will be asking questions to make sure that your design is your own original work. Upon

completion of your simulation demonstration, the TA’s will sign and apply a grade to your report

template. You also need to include these simulations into your lab report template.

Second, you will need to implement ONE design using the TTL parts you used in earlier

lab work and demonstrate to only a CSE/EEE 120 hardware TA that your circuit works

correctly. You must complete this demo by the due date (See Table 1 below). You will need

to sign up at the front desk in GWC 273 for a time slot in which to build your hardware

demo. After reviewing the simulation TA’s signature on your Logisim schematic printout, the

hardware TA’s will test your design and stamp the design pages of your completed report

template. You must be able to explain why your circuit responds the way it does to a given input

data stream. You must have your report template completed and bring it with you to your

in-lab hardware demonstration. Your completed report template will be collected by the

hardware TA at the conclusion of your demonstration.

You must use the design project template for your report.

Lab project make-ups will be allowed ONLY with written permission from your instructor.

You may discuss this project with each other; however, you must provide an individual report.

In addition:

(1) You must go to the GWC 185 individually to demonstrate your simulation of both

designs AND

(2) You must go to the hardware lab individually to build one circuit in order to have your

individual report count.

1Grading Policy

The grade will be allocated as follows:

30% Design Simulation With Logic Works or Logisim

 15% for the design of the first circuit and demonstration.

 15% for the design of the second circuit and demonstration.

70% Build One Design in the Hardware Lab and Lab Report

 30% demonstration of one design in the hardware lab.

 11% for documentation in the report of how the first circuit performs the application.

 11% for documentation in the report of how the second circuit performs the application.

 5% for establishing reasonable criteria for picking one design as the “best” design. (The

one design you build in the hardware lab does not need to be the “best” design.)

 8% for picking a preferred, “best” design.

 5% for following template guidelines.

5% (Extra Credit) Completed Self-Assessment Worksheet

5% (Extra Credit) for signing up for a Hardware Demonstration time slot on a Tuesday or



Baumann &

Matar & Reisslein

Table 1: Period of Performance



Begin Hardware



Demo Time Slots



Apr 19

Apr 22 (5 PM)

Apr 26

End Hardware

Demo Time Slots

Apr 29 (6 PM)

2The Application: Gas-Pump Controller Design

The Clean Petroleum Company (CPC) is interested in reducing pollution in the atmosphere.

When people overfill their gas tanks gas is spilled and evaporates causing air pollution. To

minimize this problem, their pumps currently turn off when the back pressure from the gas tank

gets too large while the nozzle handle switch is activated (i.e., compressed).

They have asked you to design a controller that does the following: If the nozzle handle switch is

depressed and the pump pressure sensor indicates low pressure, then allow gas to be pumped. If

the pump pressure sensor indicates high pressure then turn-off the pump. (The system clock

pulses every one second and you may assume that once the pump shuts off, the pump pressure

returns to normal within one second.) Once the pressure returns to normal, allow the pump to be

controlled again by the nozzle handle switch. If the pump pressure sensor indicates high pressure

a second time, your design will permanently shut down the pump until reset by gas station

personnel. (Note that there are two inputs to your synchronous machine: the nozzle handle

switch position, and the pump pressure sensor indicator. Your synchronous machine has one

output that controls the pump.)

All information to complete this design may not be specified. Write down and report any

assumptions that you make in your design.

Be sure to use debounced “logic switches” for driving the clock input to the flip-flops.