Studio #6

Name of Students in Team (max 3) / Student ID Number / Section

6.1. Getting to know digital hardware

Studio 6.1 – Learning to build simple circuits.

6.2 Summarize Your Reading

Summarize key points from Sections 3.4 and 5.3 from Katz textbook.

Hand in for Grading to your Studio TA:

At the end of today’s session: Studio 6.1 signed off

- one per group of students: at most 3 per group.

At the beginning of the next studio session: Completed studio with summary

- one per group of students: at most 3 per group.

6.1 / 6.2 / Total
Correct functioning of circuit
(30 points) / Work area cleaned up properly
(20 points) / Clean, organized, and understandable wiring
(20 points) / Use of consistent color conventions for wires
(10 points) / Summary of Reading
(20 points) / 100 points

Grader’s Signature :______

Studio 6.1

Step 1: Obtaining the equipment

One team member should go to the left back door of the studio and check out a “prototyping board,” and a bag of circuit modules. You may need to deposit your Rensselaer ID card for this with the TA. The prototyping board and the circuit modules are numbered identically.

You will use this protoboard and circuit modules for the duration of this course, and they should be returned in the same condition you received them in.

Another team member should go to the right back door of the studio and check out a toolbox. Again, you may need to deposit your Rensselaer ID card for this with the TA. The toolboxes will be shared between students in other sections as well as students in other courses, and should be handled very carefully.

The chips are stored in the cabinet on the left end of the studio in labeled boxes. You must return the chips to the proper boxes after use.

Step 2: Getting to know the equipment

A. The bag of custom circuit modules

There are 5 modules:

1. Module with four binary switches: Pins 1 – 6 are wired up as follows:

Pin Number / Meaning
Hi – 1 / +5V
Hi – 2 / Ground (0V)
Hi – 3 / Data bit #4 (switch #4)
Hi – 4 / Data bit #3
Hi – 5 / Data bit #2
Hi – 6 / Data bit #1 (switch #1)

2. 6-bit LED (light emitting diode) Display board

Pin Number / Meaning
Hi – 1 / +5V
Hi – 2 / Ground (0V)
Hi – 3 / Data bit #6 (Lamp #6, red)
Hi – 4 / Data bit #5, red
Hi – 5 / Data bit #4, yellow
Hi – 6 / Data bit #3, yellow
Hi – 7 / Data bit #2, green
Hi –8 / Data bit #1 (Lamp #1, green)

3. 7-segment displays with decoders/drivers (two of them)

Pin Number / Meaning
Hi – 1 / +5V
Hi – 2 / Ground (0V)
Hi – 3 / Data bit #4
Hi – 4 / Data bit #3
Hi – 5 / Data bit #2
Hi – 6 / Data bit #1
Hi – 7 / Enable

4. Two-speed (switch selects between 1 Hz and 10Hz speeds) clock pulse generator

Pin Number / Meaning
Hi – 1 / +5V
Hi – 2 / Ground (0V)
Hi – 3 / Clock out

B. The toolbox

The toolbox consists of the following items:

Multi-meter / Use this to measure voltages, resistances, currents, etc.
Logic probe / Use this to probe the logic levels (0 volts and 5 volts). Connect the red wire to +5volts, and the black wire to ground (0 volts). Touch the tip of the probe to a part of your circuit to determine its logic level. The small lights on the probe indicate the logic levels.
Wire stripper / Use this to strip the plastic insulation off wires. Make sure that the stripped plastic is properly disposed of in the trash can.
Wire cutter / Use this to cut wires. Make sure that the small wire pieces are properly disposed of in the trash can.
Long nose pliers / Use this for bending wires.
Chip puller / Use this carefully to pull chips off the protoboard.
Screw driver / Use this to adjust device such as trimmed potentiometers.
Power leads / Use these to connect the power supply to the universal protoboards. Use the following color convention: Red: +5 volts; Green/Black: Ground (0 volts);
Purple: -12 volts; Yellow: +12 volts.

C. The prototyping board

You will do all your wiring on Universal Protoboards (prototyping boards, also known as breadboards). This board consists of an array of holes separated 0.1 inch from each other. The pins on integrated circuits (ICs), commonly referred to as “chips” are also separated 0.1 inch. The holes on the protoboard are connected internally in rows and columns as explained below.

Observe the areas with two columns of holes each. These holes are connected together lengthwise, as indicated in Figure 1. These buses are usually used for power and ground connections. Do not place components such as integrated circuits (ICs) on this bus.

Observe the areas lwith more than 2 columns of holes. These holes that are connected in the other direction. This part of the protoboard is where you will place ICs and discrete components such as resistors, capacitors, etc. Refer to Figures 1 and 2 for proper placement and connection of ICs. In these figures, there is a +5V "bus" and a GND "bus". Any wire connected to this bus will be connected to either +5V or GND (provided these power signals have been connected from the power supply).

It is a good practice to always use red colored wires for +5V lines and black wires for GND lines. The black object in these diagrams represents an IC (Integrated Circuit) which you will use in this course. All ICs have a notch or dot at one end that helps us figure out their orientation. The pins are usually numbered counter-clockwise starting from the pin below the notch (when viewed from above). For instance, Figure 2 shows pin number 11 of this IC connected to GND, and pin number 22 connected to +5V.

Figure 1: Showing how the protoboards are wired internally (shown by the thick arrows), and also the procedure for placing chips.

Figure 2: Showing the connection of ICs. In particular, this diagram shows pin number 11 of this IC connected to GND, and pin number 22 connected to +5V.

Some guidelines for wiring circuits

·  Plan your layout in advance: Look at the way the pins are arranged on each chip and try to place your chips on the protoboard so that they can be connected easily.

·  Modular layout: When you have to build a large circuit, it makes sense to build it in small pieces (“modules”) that can be tested independently, and subsequently connected together. Later, when you are trying to debug your circuit, it makes sense to disconnect the major modules, and test them independently. Try to plan your layout with such modularity in mind.

·  Test each part beforehand: It is often possible for you to encounter chips that are defective. It is a good idea to test each chip before it goes into a complicated circuit. It is a lot harder to locate a defective chip later!

·  Color coding of wires: Be very neat, and follow a systematic color scheme for your wires (see Figure 2 ). For instance, the color red is typically used for +5volts and black is usually used for Ground (0 volts). Use other colors in a systematic manner. This will help you debug your circuits more easily.

·  Avoid “loops”: Try to connect any pair of points in your circuit with a wire that runs close to the protoboard, and is as short as possible. Whenever we have wires that stick out to form “loops” on the board, we run the risk of this loop acting as an antenna, and introducing unwanted electrical disturbances into our circuits.

Figure 3: An example of good wiring.

·  Use supply bypass capacitors: Ideally, the power supply is a rock-steady voltage waveform at +5V and 0V. In practice, however, the supply waveform is "noisy", i.e., it has a small rapidly-fluctuating component. This fluctuating component is usually because of surge currents drawn by each of the little transistors in our digital system, and because of the inability, due to high inductance, of the power supply to meet these surge current requirements. Also, every now and then, one may find large transient fluctuations. These effects can sometimes become large enough to cause unwanted changes in our digital circuit. "Supply Bypass Capacitors" help us in this regard. A capacitor has a high impedance to dc and a low impedance to voltage fluctuations. Putting a large (eg. 0.1mF) capacitor between the +5V and ground pins of your chips effectively short circuits the fluctuations without affecting the steady dc voltage. We can think of bypass capacitors as storing charge that can be used to quickly supply surge current needs.

When wiring supply bypass capacitors, we need to be careful!! Here’s why. When you pick a large (0.1mF – 10mF ) capacitors, you are most probably using an “electrolytic capacitor”. Electrolytic capacitors cannot handle positive and negative voltages. They are usually marked quite clearly with plus "+" and/or minus "-" symbols to indicate their preferred polarity. You can damage them by wiring them with reverse polarity. Usually, the damage is accompanied with overheating and sometimes, a small explosion!!

D. Connecting power to the prototyping board

Never apply power to your circuit until you have checked all connections carefully. In particular, check for short-circuits. Shorts between power and ground will probably not harm the power supply, but it could be disastrous to your circuit. Also check the polarity of devices such as electrolytic capacitors. Many devices can be destroyed by improper connection.

A labeled portion of the protoboard consists of terminals for attaching power leads (they should be in your toolbox). Use the following color convention:

·  Red: +5 volts

·  Green/Black: Ground (0 volts)

·  Purple: -12 volts

·  Yellow: +12 volts

Step 3: Design and Build two Simple Circuits

For this exercise, we will wire up our circuit modules, and get to know them.

Task #1 (10 points): Use the module with four binary switches to generate a 4-bit input to the module with the seven-segment display. Use the logic probe to confirm the values of S1 – S4. Record the displayed characters in the table below:

S1 / S2 / S3 / S4 / Displayed Character
0 / 0 / 0 / 0
0 / 0 / 0 / 1
0 / 0 / 1 / 0
0 / 0 / 1 / 1
0 / 1 / 0 / 0
0 / 1 / 0 / 1
0 / 1 / 1 / 0
0 / 1 / 1 / 1
1 / 0 / 0 / 0
1 / 0 / 0 / 1
1 / 0 / 1 / 0
1 / 0 / 1 / 1
1 / 1 / 0 / 0
1 / 1 / 0 / 1
1 / 1 / 1 / 0
1 / 1 / 1 / 1

Task #2 (20 points): Use the pulse generator module to generate a 1-bit clock input. Call this signal X. Use an inverter gate to produce the complemented clock signal . Connect X to the green lamps on the module with six colored lamps. Connect to the red lamps. Wire up the yellow lamps so they are always on.

Demonstrate to your grader that the green and red lamps blink constantly, they are not ON at the same time, and that the yellow lamps are always ON.

Step 4: Signoff and Cleanup

You must demonstrate your circuit to your TA and get it signed off and graded. The grade is recorded immediately on the cover page.

You must cleanup after yourself. Specifically, please make sure that there are no pieces of wires or plastic on the tables and floors. All pieces of wires are to be placed in the trashcan. Keep in mind that your TAs are instructed to not sign off on your activity unless you clean up properly.

6.2 Summarize Your Reading (20 points)

1. (10 points) Summarize key points from Section 3.4 from Katz textbook in the space below

2. (10 points) Summarize key points from Section 5.3 from Katz textbook in the space below

ECSE-2610 Computer Components and Operations, Fall 2000 Page 8 of 9