You are to design a clocked sequential circuit to control a photocopier. The number of copies desired is to be specified as a 4-bit binary value (up to 15) using DIP switches. The copier is to have a Start button that is depressed once the desired number of copies has been set on the DIP switches. The number of copies produced by the copier is to be displayed on a hex display. Imagine the copier consists of four mechanical subsystems: the Feeder, the Imager, the Fuser and the Collator. A paper jam can occur in any one or more of this subsystems and will be indicated by a logic one on the respective input. Whenever there is a paper jam, the Jam light is to come on and copying stopped. Copying is to begin again when the jam is cleared and the Start button is pressed. The copier is to take about 8 seconds to deliver the first copy (initially and after a jam is cleared) and to produce a copy about every 2 seconds there after. Depression of the Start button while the copier is running is to stop it. Before the copier stops in response to depression of the Start button, any in-process copies are to be delivered. The copier is to stop automatically when the specified number of copies has been produced.
Optional Extra Credit Features:
Write a formal report describing the methods you use in your design and the outcome of your work. Your report must contain the following sections:
Problem Statement This section should describe the basic problem you solve and list any assumptions you made and limitations of your design.
Design Procedures This section should include an explanation of your notation, state diagrams, state tables, excitation tables or an ASM chart as needed.
Design Description This section should include a natural language description of your design, block diagrams and logic diagrams as needed.
Implementation Description This section should include a parts list and wiring diagram for the implementation of your design.
Testing Procedures This section should include a detailed description of how you tested your design and the results of those tests.
You may include other supporting documents in your final report as you think necessary. Be sure that you discuss the rationale you used to select among the various options available to you in the design. It should be possible for another group of EE-290 students to reproduce every step of your design and implementation process using your report.
You must implement your design and demonstrate it to me (and the rest of the class) during our lab period in the tenth week of the quarter. The demonstration will include an oral presentation (with handouts, visual aids, etc.) to the class and answer questions period. Work in groups of 2 or 3 with one demo and report per group.
I will grade your reports on the basis of professionalism (grammar, neatness, etc.), completeness, originality and success.
Critical Dates:
| 5/1 | Project assignment and group formation. |
| 5/8 | Draft of Problem Statement and Design Procedures (state diagram, ASM chart, etc.) due. |
| 5/12 | Draft of Design and Implementation Descriptions due. |
| 5/15 | Demonstration and presentation starting at 9 :00 a.m. |
| 5/16 | Final reports due. |
Hints and Tips:
Use pull up resistors with the DIP switches and current limiting resistors for any non-Digi-Designer LED's you use.
Consider using 555 IC timers (a 556 chip contains dual 555 timers) for the real time outputs. In previous years, students have found them to be more reliable than 7400 series one-shots (astable multivibrators). The one-shots seemed to be very sensitive to noise inherent in breadboard implementations. These timers are triggered by an active low pulse. Guard against "glitches" that can set off the 555 timers inadvertently.
Consider using a counter and control logic based design and an ASM chart.
Consider using PLD's for your design.
Consider using type D flip-flops and an EPROM for your design. This allows you to use my ST2HEX2 program (available from: http://www.msoe.edu/~tritt/eproms.html ) to translate your state table directly into a hex file. This will allow you to implement your design with 3 or 4 chips.
Manage the risk in your project. Get the minimum done first and then add features or attempt advanced techniques as time permits. Use a modular approach and test subsystems separately.