Each group must design and build a combination security lock device controlled by digital electronics and/or a PIC microcontroller. Your device must contain the following minimum set of functional elements:

  • three switches (labeled A, B, and C) that will be used to enter a combination
  • a button (labeled ENTER) used to process the input (the states of A, B, and C) and perform the appropriate function as described below
  • a green LED labeled OPEN and a red LED labeled ALARM used to indicate the result of a combination attempt

Your group’s grade for the project will be based on the level of performance that your device achieves and on several scoring adjustments as described below.

Levels of Performance

The levels of performance along with their corresponding base scores (based on a scale of 100) are:

Level 0 (0)
Non-existent or non-functioning device.

Level 1 (60)
When the ENTER button is held down, the green LED should be on if the A/B/C switches match the desired combination and the red LED should be on if there is a discrepancy. The LEDs should be off when the ENTER button is up. The correct combination must be pre-programmed inside of your device (e.g., with a small set of DIP switches or with constants in a PIC program).

Level 2 (70)
Level 1 plus your device should keep track of and display the number of failed attempts since the last valid combination. We only require a count up to nine so a single 7-segment LED display will suffice. The display should reset to zero when the valid combination is entered.

Level 3 (80)
Level 2 plus your device must also sound a buzzer or alarm for approximately 3 seconds when an incorrect combination is entered. If the correct combination is entered during an alarm, the alarm should be turned off immediately.

Level 4 (90)
Level 3 plus your device must also contain some sort of actuator (e.g., solenoid, dc motor, or stepper motor) that performs some interesting function (e.g., unlatches and springs open a locked door) when the correct combination is entered. We want you to be creative with the action and function of the actuator and the intended use of your device.

Grading Adjustments (added to or subtracted from the base level score)

  • +/- 5 for construction quality, aesthetics, consumer appeal (e.g., perforated protoboard with neat soldered wiring vs. messy breadboard; well-built and attractive packaging) (-5: poor; 0: average; 5: exceptional)
  • +/- 5 for level of effort, initiative, and research (-5: low; 0: average; 5: high)
  • +/- 5 for actual construction cost and expected mass production cost appropriate for the level of performance (-5: expensive; 0: average; 5: inexpensive)
  • + 5 [for Level 4 only] for creativity, originality, and usefulness (0: average; 5: exceptional)
  • +/- 10 for the final project report per the requirements below (-10: poor; 0: average; 10: exceptional)

NOTE – The potential for a positive adjustment increases with the level of performance. A maximum positive adjustment is possible only for a Level 4 device (especially for the final report adjustment).

Extra Reward:

  • +5 (max) for a presentation in class during the last week of the semester (by invitation only)

Additional Information:

  • Your TA will try to provide you with any circuit components you need (resistors, capacitors, LEDs, limited IC’s) and Walt can supply you with limited building materials and mechanical hardware. You are responsible for purchasing other stuff (special IC’s, switches, buttons, miscellaneous mechanical and electrical accessories, etc.). See useful local vendors.
  • We recommend that you work together as much as possible with your group members, but the project work may be more manageable if you divide tasks among the group members. The entire group is still responsible for the work (e.g., if one group member doesn’t do their parts, the other members must take up the slack and evaluate the non contributing member accordingly). Here is an example of a list of duties you may want to distribute among your group members:
    • project management (schedule meetings, plan and monitor progress, budget and collect for purchases, foster communication, etc.)
    • product and component research and purchasing
    • mechanical hardware design, assembly, and testing
    • electronics design, assembly, and testing
    • PIC microcontroller programming and interfacing
    • design documentation and report writing
  • If your device fails to satisfy a level’s requirements exactly or if your device’s performance falls between two levels, the score will be adjusted accordingly.
  • Official trials will be during the Lab section meetings in the latter part of the semester and during other hours arranged by your TA (e.g., TA office hours). No trials will be allowed after the last class day of the semester. You may use multiple trials to progressively improve your Level score. A group is allowed only one official trial per week. Every group must also show their device during the last Lab section meeting for final evaluation of the grading adjustment categories. You are welcome to invite family and/or friends to the final Lab section meeting to see everybody’s designs.
  • Selected groups will be invited (by your Instructor) to present their projects to the entire class during the last two lecture periods of the semester (see “Extra Reward” above).
  • The final report is due at the last meeting of your Lab section. The report should include:
    • title page with title, group number, group member names, date, etc.
    • Design Summary: concise overview of what your device does and how it works. Include a well-labeled overall figure illustrating your device.
    • Design Details: detailed figures (where necessary and/or helpful), circuit schematics and/or functional diagrams, and software flowcharts (if applicable). Be sure to refer to the figures and diagrams in the text and describe them completely.  Include detailed wiring diagrams (if details are not included in earlier figures) and well commented software listings (if applicable) in an Appendix and refer to them in the body of the report.
    • Design Evaluation: describe the level of performance and provide justifications for the grading adjustments.
  • Theoretically, the highest possible score (for a device and effort awesome in every way and presented well) is 125 on a scale of 100!
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