ECE 2504: Introduction to Computer Engineering

Laboratory Manual

Contents

1. Lab Kit Description

2. Suggestions on Project Management

3. IC Descriptions

4. Instructions for Drawing Circuit Schematics

5. Circuit Breadboarding and Wiring

6. Lab Kit Familiarization

7. Project Grading Guide

Revised January 2004

Please send any comments and corrections to Dr. N. J. Davis IV, ndavis@vt.edu

Virginia Polytechnic Institute and State UniversityThe Bradley Department of Electrical and Computer Engineering

1

1. Lab Kit Description

Description: The LD-1 Pencilbox™ Logic Designer kit is an instrument which makes it easy to implement and test digital circuits. It can be used in the study and design of logic gates, counter, multiplexers, and flip-flops, and can even be used for simple microprocessor circuits. This section describes the lab kit hardware; Sections 4 and 5 describe how to use the kit for course projects.

The unit contains 8 LED indicators, 8 toggle switches, 2 debounced push-button switches, and a clock. The LEDs are sometimes call “logic indicators,” and can be used to display output signals from digital circuits that are built using the kit. They may also serve as independent logic probes for circuit testing. The toggle switches, also called “logic switches,” can be used to provide input signals to a digital circuit. The push-button switches, sometimes known as “pulsers,” provide logic pulses that are also used as input signals to a circuit. The pulse lasts as long as the button is depressed. The clock provides a square wave at approximately 1 kHz. Because the clock is so fast compared to the needs of the 2504 labs, it is generally not used.

All of these functions are internally connected to a solderless interconnect socket with five tie points for each signal. In addition, a general-purpose socket (or “breadboard”) is provided as a convenient work area for circuitry being designed or studied. Both sockets allow insertion of components or wires up to size 20 AWG in diameter. Power is supplied to the kit by a wall transformer.

The unit is housed in a durable plastic case with a hinged cover. This makes it possible to partially implement a circuit and then store or transport the entire kit for later use or evaluation.

Important: 1. Do not write on or attach tape to the lab kits. Use slips of paper or Post-Its™ to label displays but do not

tape them in place.

2. Use care when inserting or removing ICs. Damage is possible.

3. Do not attempt to repair a malfunctioning kit. Instead, demonstrate the problem to a GTA, and obtain a handwritten note, which describes the problem. Take the note to the ECE Shop, where the kit will be repaired or replaced.

4. When checking out a kit, be certain that everything is included. Otherwise, the shop attendant will charge you for any missing components.

5. Use the recommended wire size (diameter). Oversize wire will stretch the connector sockets. Undersize wire will result in unreliable or intermittent connections. See Section 4B.

2

2. Suggestions on Project Management

The following items are suggestions to make the completion of your project assignments easier. Many should be “common sense.” However, the instructors, lab engineers, and GTAs that work with ECE 2504 have found that repeating them here helps! Good luck. Allow plenty of time to complete your project. Plan for the unexpected….

IDENTIFY AND USE THE RESOURCES THAT ARE AVAILABLE TO YOU • The project assignment itself. • Classroom discussions where your instructor may overview the project and answers questions. • Textbooks and other reference materials. • CEL and other web pages. • Instructor/Professor’s office hours. • Help from CEL TAs. • Study groups.

READ! Most of your questions can be answered by reading the materials that are available to you. • Read the entire assignment before beginning your design.

• Read the entire assignment – again! • Read the project validation page.

• Read your class notes, your textbooks, the 2504 CEL web pages. • Read the supplementary documents that are referenced in the assignment or mentioned in class. • Read the whiteboard in the CEL for last-minute updates

REQUIREMENTS: What do you need to obtain in order to do the project? • Datasheets? • Schematic diagrams? Printouts? • Parts? • Pencilbox checkout dates and times? • Wire? Chips? • Reports? Style?

TASK SEQUENCING: How should you sequence the completion of the project? • Have you split the project into clear objectives?

• Work in stages. Decompose the problem into several tasks, and make sure one thing works before starting another.

• Complete your design. Print your schematic. THEN, start building – from the final schematic! • Test and debug your project. • Have your project validated once everything works. If you cannot get it to work properly, have a GTA validate

what does work to avoid a “0” for the validation grade. • Write the report. Address validation difficulties (if any) in the report!

3

TIMELINE: Failure to manage your available time is the single biggest problem in completing your projects • How many days or hours until the due date?

• Start your projects early. • Expect problems to occur and allow time to resolve them.

• Do you have other concurrent projects or tests that impact the completion of this project? • Budget your time so as to get the project done at least 2 days before the due date – to allow for unexpected

events. • Many projects take 4 times the amount of time that you have budgeted. • In half the budgeted time, have you finished more than half the project? • Check to see if there is a list of names, waiting for validation, on the CEL whiteboard.

CRITICAL ITEMS • Do you understand the assignment? • If you are stuck on a question or concept, ask someone NOW! • Fill out your validation sheet items with a pen, not a pencil. • The CEL supports multiple sections of 5 courses and over 700 students. Plan for crowds. • The validation queue in the CEL increases as due dates approach. • Most classes validate the same week, then skip a week. • Logon and test your project BEFORE requesting that a TA come to you for a validation. • What if one of your chips is bad? • Before turning in the project deliverables, make sure you have included everything. • All items you turn in must be well documented and referenced in the body of your report.

LAST MINUTE THINKING • What works? What doesn’t work? • Am I using the same old technique that has failed? What about a fresh approach? • Can I get partial credit on the validation? • How can I improve this process so I don’t end up here again? • When should I cut my losses and stop wasting time and CEL resources?

TROUBLESHOOTING SUGGESTIONS • Check for chips installed backwards (i.e., is pin 1 of the chip where you think it is on the breadboard)! • Check ALL of your power and ground pins on ALL of your chips. • Compare signal by signal with your simulation. • If you wired something incorrectly, it will probably look right to you – repeatedly. Have someone else check

your circuit. • Don't plan to do your project design and construction the night before it is due, run to the CEL to get it

validated on the way to class, and somewhere along the way write the project report. If everyone does this, there will be a crowd in the lab, and you may not get your project validated in a timely fashion.

• Learn how to use the chip tester in the CEL. • Make sure that all enable, clear, set pins are properly connected. • Never leave input pins open.

4

3. IC Descriptions

Much more information on the ECE 2504 Integrated Circuit chips can be found on the CEL Web Page under Data Sheets.

Your chip set should contain the following parts:

Qty # Description 3 7400 2-input NAND Gates 2 7404 Hex Inverters 2 74153 Dual 4-input Multiplexers 1 74175 Quad Positive-Edge Triggered D Flip-Flops 1 74283 4-bit Adder 1 TIL321A 7-Segment LED Display 5 - 330 Ohm Resistors

Note: Parts labeled 74xx and 74LSxx are functionally identical. The LS parts are “faster” components (lower propagation delays).

Refer to Figures 1-4 for pin assignments of the ICs used in this course.

5

7400

7404 Figure 1: Pin Assignments for 7400 and 7404.

6

74153

Function Table

H denotes high (logic level 1) L denotes low (logic level 0) X denotes “don’t care”

Figure 2: Pin Assignments and Function Table for 74153

7

16 15 14 13 12 11 10 9

1 2 3 4 5 6 7 8

Vcc Q4 Q4 D4 D3 Q3 Q3

GNDD1Q1Q1 D2 Q2Q2CLEAR

CLOCK

74LS175 Quad D Flip-Flop with Clear 74LS175

4-Bit Binary Adders with Fast Carry

74LS283

16 15 14 13 12 11 10 9

1 2 3 4 5 6 7 8

Vcc B3 A3

B2 B1

B4

A1

A4

S1

S3 S4

C0A2

C4

S2 GND

ab

sci co

ba

sci co

a b

scico

b a

scico

FA FA

FA FA

Figure 3: Pin Assignments for 74LS175 and 74LS283

TIL-321A 7-segment display: A given segment of the display is lit when a logic 0 is applied to its input through a current limiting resistor. See the sketch in Figure 4. For more information see TIL-321A datasheet on CEL web page. CAUTION: The TIL-321A display contains eight light emitting diodes (LEDs). (Seven segments plus decimal point.) To light an LED diode that corresponds to a given segment, current must be passed in the forward direction through the diode (anode more positive than cathode pin). This takes about a 2.0 volt “drop” across the diode. To drop the remaining 3.0 volts of a nominal 5 volt “logic 1,” a resistor must be placed in series with each LED diode, as shown in Figure 4. An LED will be destroyed if a resistor is not connected in series with it. (Your driving gate may also be ruined.)

8

7 - Segment Display

WORKSHEET

0

1

2

4

5

7

8

9

3

6

ab

c

d

ab

c

d

ab

c

d

ab

c

d

ab

c

d

ab

c

d

ab

c

d

tu

vwx

y z

x

z y utA

vw A d

Display Elements

Pin Connections (top view)

Type: TIL321A Common Anode

See Caution!

Example connection: Segment w lights when Nand gate output equals logic 0 (0 volts).

logic 1 (+5v) A

w330 ΩA - anode

d - decimal point

Figure 4: Pin Assignments for the TIL321A.

9

4. Instructions for Drawing Circuit Diagrams

For project reports, all circuit diagrams should be drawn using Logic Works. In general, two types of circuit diagrams will be required. The first diagram is a gate-level logic diagram. An example of this type of diagram is shown in Figure 5. Individual, gate-level components are shown in such diagrams. Based on the specific requirements of the individual labs, students may be expected to include such circuit diagrams for portions of their designs or their complete designs.

Figure 5. Example Logic Diagram

In addition to gate-level logic diagrams, students will generally be required to submit a final IC device-level wiring diagram as part of their lab report. This diagram may also be reviewed by the GTAs as part of the lab validation process. The IC device-level diagram shows the complete, final circuit that is to be implemented on the Pencilbox using the individual IC devices such as the 7400 NAND gate chips. Each chip should be positioned in the diagram along a “straight line” in such a way as to match its relative position on the Pencilbox breadboard. This should clearly show the position of every component used in the circuit. An example is shown in Figure 6. In addition to the placement of each IC, all interconnecting wires between gates on chips should be included in the diagram. Thus, the IC device-level diagram can be used as an aid when wiring the circuit on the Pencilbox and when troubleshooting the circuit. As each wire is inserted into the Pencilbox, the corresponding “wire” in a printed copy of the diagram should be checked off. The wiring process is completed when all of the “wires’ on the diagram have been checked off.

Use the following guidelines when preparing your wiring diagrams:

1. In your logic diagrams such as Figure 5, use the library of primitive gates (AND, OR, etc.) rather than 7400-series chips. IC device-level diagrams depict parts placement on the breadboard and should use the chip components from the parts library.

2. Every input signal and every output signal to the circuit should be clearly labeled. Inputs are labeled by the switch (S0 - S7) or pushbutton number (PB1, /PB1, PB2, /PB2), and outputs are labeled by the LED indicator number (L0 - L7) or are connected to a display chip. In Logic Works, do not use the LED for LED indicators (since the logic is negative), but use a Binary Probe instead. See L3 in Figure 5.

3. Each logic element should be labeled by an identifier. As shown in Figure 5, it is a good idea to use different letters to represent different ICs and different numbers to designate individual gates within each package. For example, a 7400 package contains 4 NAND gates; these might be labeled as N1, N2, N3, and N4.

4. Pin numbers should be shown for every IC connection used in the circuit. All pin numbers should be placed outside the schematic elements.

5. For higher-level components, such as multiplexers or flip-flops, mnemonic labels should also be given for every signal. For example, J, K, and CLEAR (etc.) will greatly help in the understanding of a logic circuit containing a JK flip-flop. These labels should be placed inside the schematic elements.

10

330

330330

330

PB1

S5 S3

S1

Gnd

Vcc

175

MR

Q0 Q

0

D0

D1 Q1

Q1

Q3

Q3 D

3

D2

Q2 Q2

CP

9

1 4 51213 10111415

6 72 3

16

8

Gnd

Vcc

00

2 4 5

9101213

3 6

811

114

7 a

gdot

DISP

+5V

04

Vcc

Gnd

1 3 5

13 11 9

2 4 6

12 10 814

7

+5V +5V +5V

Figure 6. Example IC Device-level Circuit Diagram

5. Circuit Breadboarding and Wiring

(Or, How to Build a Digital Circuit without Losing Your Sanity)

A. Overview

This section describes the procedure for wiring logic circuits with any general-purpose white prototype board for your breadboard. One of these is contained in each lab kit.

1. Before wiring any circuit, generate a neat, complete logic diagram and simulate it so you know the circuit

functions properly.

2. An inexpensive tool kit for wiring your project boards is sold through the University bookstore. The kit contains a wire cutter/stripper, small screwdriver, and forceps. If you are not sure how to cut wires and strip insulation from them safely, see you instructor or GTAs for assistance.

3. Every time you add a wire or component to the physical circuit, mark off the corresponding part of the wiring diagram with a colored pencil or marker. This makes it easy to see what parts of the circuit have been built so far. If you make any circuit changes, draw these on your wiring diagram. (For lab reports, hand in a final logic diagram that is clean and unmarked.)

4. Insert IC packages into the appropriate breadboard area before inserting any wires. You will usually need to bend the IC leads (pins) slightly inward so that the spacing closely matches the spacing of sockets on the breadboard. Be careful to check that all IC leads actually make it into the correct sockets. Also make sure that pin 1 of the IC is in the correct position.

5. To remove an IC, use an extraction tool, screwdriver, pliers or tweezers to avoid bending or breaking IC leads, or personal injury.

6. Use only solid-conductor wire in the size range of AWG 20 to AWG 26 (available for free in the Computer Engineering Lab, 368 Durham). Wire with larger diameter may damage the socket spring clips of the

11

breadboard. Wire strippers should be used to cut wires to appropriate lengths and to check wires that are suspected of having a larger diameter than permitted. Trim and re-strip the end of any jumper wire that appears badly nicked or overly flexed.

7. It is possible to insert most wires by hand. In tight places, using the forceps from the tool kit can make the job much easier. In either case, wires are easier to insert if they have been cut at an angle of approximately 45 degrees with respect to the axis of the wire.

8. When removing wires, be sure to pull at a right angle to the socket to avoid damage.

9. Route wires around IC packages, not over them. Occasionally an IC turns out to be defective. If wires have been placed over the IC, you will have to remove them so that the IC can be replaced.

10. It is best to wire a circuit in stages, beginning with power and ground connections. Add wires with the power switch OFF. Before turning power ON, remove all hand jewelry and make sure that no foreign metal objects are near the circuit. Check every IC to make sure it is not overheating. If any IC is too hot to touch immediately shut the power off and check all leads. (Be careful because shorted Ics can become very hot and leave a brand on your finger!) Also make sure that no IC has been inserted backwards.

11. IC devices can be damaged if the power level exceeds 5.5V. Damage may also occur if the supply voltage connection is removed from the IC pin while power is still being applied to the circuit.

12. To debug a circuit, use a logic indicator (L0 – L7) to check logic levels. Start at a position in the circuit where the logic level is known to be correct and work outward from there. If an IC does not appear to produce the correct signal, check that power and ground are correctly connected to the IC; also check all inputs to the component. Finally, check that the output of the IC is not incorrectly connected to some other signal.

13. If you can not get your circuit to work, bring it and a current circuit diagram or schematic to the CEL GTAs for help.

B. Wiring guidelines 1. Use new wire. A box of new wire is available in the CEL in 368 Durham.

a. Old wire can break inside the insulation, causing incorrect circuit behavior that is difficult to troubleshoot.

b. Old wire should be recycled; place old wires in the wire recycling box next to the new wire box in 368 Durham.

2. Strip 4 breadboard squares worth of insulation off the ends of a wire when using it in the pencilbox. This is

approximately 5/16 inch or 8 mm. a. If you strip too much, the wires in adjacent breadboard columns can touch, causing a short circuit

and most likely incorrect behavior. b. If you don’t strip enough, the insulation can prevent the spring clips in the breadboard holes from

closing properly around the non-insulated part of the wire that is inserted into the hole. c. An inexpensive tool set is available at the University Bookstore in the computer section. Use the

wire stripper in the kit to cut and strip your wires.

12

Figure 7: Correct length to strip wire’s insulation.

Figure 8: Wire inserts into breadboard contact.

3. Create power and ground busses at the top and bottom of your breadboard.

a. The connection pattern used in the breadboard is shown in Figures 9 and 10. b. The top and bottom rows can be used to distribute +5VDC and ground to the Ics, see Figure 11.

Note that the top and bottom “bus” rows have a break in the very middle! If you want a power or ground bus to run the length of the breadboard, you must insert a jumper in the middle of the row to join the two half rows together. This makes your wiring less crowded, and makes it easy to see power and ground connections.

Figure 9: Connection pattern used in the breadboard

Figure 10: Breadboard contacts viewed from bottom.

Figure 11: Power and ground busses wired.

13

4. Run all power signals in red wire and all ground signals in black wire.

a. Do not use red or black wire for any other signals. This makes it easy to tell which wires are power and ground wires, and which are actual signal wires.

b. Use a single power or ground wire from the bus to the chip. Do not daisy chain power or ground connections. Think parallel, not serial. See Figure 12.

c. You may wire from the bus to the breadboard hole next to the chip. This makes it easy to see that the power and ground wires are connected to the correct pin.

d. You may wire from the bus to the breadboard column that connects to the chip. This allows more room for signal wires, without covering the power and ground wires.

Figure 12: Power and ground wired from bus to chip.

5. Color code your wiring in some way. Here are some suggestions that are meant to make it easier to trace

your wiring: a. Use the same color for all the wires of a signal that runs to multiple gates. b. Use different colors for different inputs of a gate. c. If you have a bus, make all the wires of the bus the same color. However, if you have long runs of

parallel wires that are the same color, it will be more difficult to trace individual bits of the bus. Be creative.

6. Wires should be routed no more than ½” (12 mm) above the breadboard.

a. If the wires are too high, your pencilbox will not close and it will be difficult to trace signals through your circuit.

b. If the wires are low, be sure the stripped wire ends are seated firmly in the breadboard. Careful routing is essential for efficient troubleshooting. Tight wiring can create sharp bends, which can cause trouble.

7. Avoid sharp bends in the wires. Sharp bends in the wire can cause the wire to break inside the insulation. 8. Run wires around or between chips rather than over them.

a. Your chips may be defective or be damaged while in use, and it is much easier to remove chips for testing/replacement if you do not have to remove your wiring in order to remove your chips.

b. When possible, leave 2 or 3 rows of the breadboard between chips, to allow signals to pass from one side of the IC to the other.

9. Make short wire lengths from source to destination.

a. Route wires point to point, rather than squaring corners. b. Do not daisy chain power and ground wires. Think parallel, not serial. c. Do not daisy chain signal lines from a switch input to several gates. Think parallel, not serial.

14

10. Wire from a complete schematic diagram. The chip’s pin numbers should match the pin numbers in the Logicworks diagram.

11. Finally, we can compare “good wiring” in Figure 13 to “poor wiring” in Figure 14.

Figure 13: Good wiring.

Figure 14: Poor wiring.

6. Lab Kit Familiarization

Overview: This section contains a step-by-step introduction to the Pencilbox Logic Designer kit, which will be used for projects in ECE 2504. The steps below will lead you through the completion of the Diagnostic Checksheet, found at the end of this manual. Completion of this checksheet is a useful exercise that should acquaint a first-time user with the kit. These steps are also useful for checking to see if a lab kit is defective. This is not for a grade, and it may be useful if you work with someone else during this familiarization sequence.

1. First, go back and reread the earlier materials in this manual that describe the kit. Then refer to Figure 15 as you follow the steps below. The Roman numerals in parentheses refer to parts marked on the figure.

2. Find the Control Strip (I) near the center of your kit. This small white strip contains connectors with labels such as “LOGIC 1,” “LOGIC INDICATORS,” etc. This strip will provide power and control signals to your circuit, which you will build in the Breadboard area (II). The control strip also provides access to several LEDs that can be used to display signal levels in your circuit. When using the kit, you will build circuits by placing electrical components on the Breadboard and by attaching wires between different connections on the Control Strip and the Breadboard. Connections must be made only within these two areas. Do not touch any wires to components in the black area of the kit. Damage is possible.

3. Now prepare to apply power to the kit. Remove all metal objects from the vicinity of the kit. This includes hand jewelry and any stray wires. Be certain that switch S1 is OFF (III). Insert the jack (circular plug) into the circular receptacle labeled J1 (IV) into the POWER section of the kit. Next, plug the AC adapter into a standard (120 VAC) wall outlet. Move switch S1 to the ON position. This applies power to the internal circuitry of the kit only. No power is applied to the Breadboard area. Whenever you are finished working with the kit, move S1 to the OFF position before disconnection power.

4. Find the connectors labeled “LOGIC 1, +5” and “LOGIC 0, GND” in the Control Strip (I). These are the source of power for all of your devices. Be very careful when connecting wires to these areas. Although the voltage level is too low to be dangerous to you, sparks can result and you can easily damage the kit.

15

5. Look on the Control Strip for the LOGIC INDICATOR connections labeled L0, L1, …, L7. When a 5-volt signal is present at one of these connections, one of the 8 LEDs (V) is illuminated. Check out all of the LEDs in your kit by inserting a wire from one of LOGIC 1 power connectors to each of the LOGIC INDICATOR connectors in turn. Each LED should glow. It is a good idea to make this check each time you work with a kit; it could save you a lot of unnecessary effort if one of your LEDs is burned out. Except for simple, careful connections such as this, you should always turn the power switch S1 OFF before inserting wires into the kit.

6. Find the connections labeled LOGIC SWITCHES on the Control Strip: S0, S1, …, S7. These are connections to 8 switches near the top of the kit (VI). (Be careful — there are two sets of labels near the switches!) Connect switch S0 to an LED through the connection L0, and turn the switch ON and OFF a few times. Note which setting corresponds to a logic level 1 (the LED is on) and which corresponds to a logic level 0 (the LED is off). Make sure that all of the switches are functioning by testing each one in turn.

7. Find the connectors on the Control Strip that are labeled PB1, /PB1, PB2, and /PB2. (/PB1 means PB1 with a line over it.) These connect to the two push-button PULSERS (VII). Connect a wire from each of these 4 connections to a different LED (through the Control Panel!) and watch what happens as you push the PULSER buttons. PB1 and /PB1 should produce pulses that look like this:

8. Notice that the Breadboard is divided into two halves, by a central “channel.” Perpendicular to this channel are many columns of five holes each. The five holes of each column are electrically connected together. They are not connected to any other part of the lab kit. A single column will be used to provide access to one pin of an IC.

9. Power switch S1 should ALWAYS be OFF when inserting or removing ICs to prevent damage to the chips. Turn the power off and place one of the 7400 ICs near the center of the Breadboard area. Insert the chip as shown in Figure 16. The two rows of pins of the IC should be on different sides of the central channel of the Breadboard. Push the IC so that each pin of the IC is inserted into a separate hole. There should now be four unused holes for each pin along the sides of the IC. Connections can be made to the IC through any of these exposed holes. Check the pin definitions in the ECE 2504 Lab Manual, and connect LOGIC 1 of the Control Panel to the VCC pin and LOGIC 0 to the GND pin. Again using the Control Panel, connect two Logic Switches to the input pins of one NAND gate. Connect the output of this NAND gate to one Logic Indicator. Verify that the NAND gate works properly by turning power ON and trying all four possible switch settings and observing the LED.

10. Now turn power OFF, leave the 7400 where it is, and insert a 7404 IC into the Breadboard. Connect power and ground to this new IC, and attach the input and output of one inverter (part of the 7404) to a Logic Switch and Logic Indicator, respectively. Turn power ON, and observe the LED brightness as the switch position is changed. Is this what you expected? Experiment by making connections to various NAND gates and inverters.

11. You should now feel comfortable with the basic operation of the kit. If not, or if the kit seems to be defective, see a GTA or the instructor. After this brief introduction, you should feel ready to build something more ambitious.

16

Figure 15: Major components of the 2504 lab kit.

I

17

Figure 16: Inserting an IC into the lab kit. The two rows of IC pins should be on opposite sides of the central channel of the breadboard area.

18

7. Project Grading Guide

Check your instructor’s syllabus, lab assignments, or other handouts for specific report requirements. The following comments provide some general guidelines. Project grades depend not only on what you say, but also how you say it. In general, the graders will check how each project report meets the following criteria:

Format • The report must be neat. It must be prepared using a word processor program. • The report should contain a cover sheet with a signed Honor Code pledge. This cover sheet will normally

be included with the lab assignment materials that are posted on the CEL web page. • Most reports will include supporting documentation, such as wiring diagrams, validation sheets, or

computer printouts. All of these must be neat and legible. • All figures and tables must be prepared using the word processor and numbered, labeled, and referenced in

the report. • All circuit and wiring diagrams must be created with Logic Works. Note that Logic Works circuits can be

“cut and pasted” into MS Word documents, as needed.

Content • The body of the report should contain clear section headings. Usually one section at the beginning will

describe the project design requirements and objectives, and a section at the end will summarize the report. The sections in between these two should be meaningful and be used to organize your presentation.

• All descriptions must be logically consistent and easy to understand. • Assume that the lab report reader/grader is generally knowledgeable about the material taught in the

course. Thus, you do not need to define or explain common terminology and procedures. • Your report should thoroughly discuss the design process that you used to complete the lab project. You

should fully document design choices, alternatives, and tradeoffs that you evaluated and why design decisions were made. Documentation such as circuit diagrams, truth tables, Karnough maps, and timing diagrams that aid in the understanding of your design should be included in your report and discussed in the text/body of the report.

• A large portion of your lab grades will be based on how well you can write a technical report. Expectations include:

o Use of complete English sentences though out the report. o Bulleted lists should be avoided – use paragraph discussions instead. o A very common error made by students is to mix verb tense usage in the report (or even within

individual sentences). This is very poor! In general, use the past tense to describe work that you have already completed.

o Avoid the use or the over use of the “first person” writing style. In technical writing, “I,” “me,” “we,” etc. are generally not considered to be “good style.”

o Proofread your report for spelling, grammar, and coherent structure. o For help in this area, refer to the writing guidelines at the following web page:

http://www.writing.eng.vt.edu/

Project Wiring Neatness: The wiring neatness evaluation of your project starts with a score of 10. Each missed item, below, deducts one point. • Wires stripped according to discussion in Step 3 of the Wiring Guidelines in Section 4B of this manual.

a. Too long (wires short together) (minus 1) b. Too short (insulation goes down into breadboard) (minus 1)

• Wires go across chips (minus 1) instead of around chips (good)

19

• Ambiguous wire colors a. All wires are one color (minus 1) b. Can't tell which wires are power or ground (minus 1)

• Daisy chain wiring a. Series power distribution (minus 1) b. Series signal distribution (minus 1)

• Wire length a. Can't close box (minus 1) b. Random wire lengths (minus 1)

• Physical chip pin numbers don't match Logicworks schematic (minus 1)

Diagnostic Checksheet for LD-1 Pencil Box Digital Trainer

Use this checksheet to perform an initial check of your trainer kit. Check each box to the left of item as completed. If you think you are having trouble with your kit, discuss you problems with you instructor and ECE shop personnel.

Name : ___________________________________ _____ Student No : ____________________

1. Inspect the unit for missing parts, improper parts orientation, etc. Correct any obvious problems before starting.

2. POWER SUPPLY OPERATION Connect wall power supply 1/8” phone plug to J1. Turn switch to “ON”. Connect wire between Logic 1(+5) and Logic indicator L0(A). “D0” LED should light up, turn power switch “OFF” and back “ON” to verify this.

3. LOGIC INDICATORS

a) Repeat step 2 for all LEDs. b) Test L1(B)—L7(H)

4. CLOCK SECTION

Connect wire from L0(A) to “CLOCK OUT”, “D0” LED should light up, (some trainers have a slow clock, therefore the LED will be blinking at a slow rate (~1/sec).

5. PULSERS a) Connect a wire from L0(A) to PB1 (signal HIGH in figure). b) “D0” LED should light when PB1 is depressed. c) Move wire to PB1 (signal LOW in figure). d) “D0” LED should go out when PB1 is depressed. e) Checkout PB2, PB2 in like fashion.

6. LOGIC SWITCHES (Note : Do NOT use a GRAPHITE PENCIL TO MOVE SWITCHES !!!)

a) Connect a wire from L0(A) to S0(A). b) Set switch “0” so that “D0” LED is lit. This is defined as the OPEN position. (LOGIC 1 position). c) Set all 8 switches to OPEN. d) Connect a wire to all 8 indicators, L0(A) thru L7(H) to corresponding switches S0(A) thru S7(H). Each LED

should light up when it is connected. e) Move each switch to NOT OPEN then to OPEN, noting that only the corresponding LED went out.

9. Turn POWER switch off. This concludes test.

I have performed the above procedure and am satisfied the kit is working properly. Comments :

Signature : ____________________ Date : __________