THE ISLAMIC UNIVERSITY OF GAZA

ENGINEERING FACULTY

DEPARTMENT OF COMPUTER ENGINEERING

DIGITAL DESIGN I LAB – ECOM 2013

Eng. Lamia Z. Shu'shaa

September 2017

Experiment #0

Introduction

DIGITAL DESIGN I LAB ECOM 2013 ENG. LAMIA Z. SHU'SHAA

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Objectives:

To be familiar with Logisim software and lab equipments.

PreLab: Try to download Logisim on your PC and look on its tools.

Logisim: Logisim is an educational tool for designing and simulating digital logic circuits.

With its simple toolbar interface and simulation of circuits as you build them, it is

simple enough to facilitate learning the most basic concepts related to logic

circuits.

Logisim requires Java 5 or later. If you do not already have it on your

computer, Java is available from http://java.com/en/download/win8.jsp.

Download Logisim from Logisim's SourceForge.net page.

Figure 1: And gate simulation using Logisim.

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Environment Layout:

Figure 2: A labeled view of the user interface

Toolbar: The toolbar contains short cuts to several commonly used items

• The poke tool (shaped like a hand) is used to alter input pins.

• The input pin (green circle surrounded by a box) is used to send a signal through a wire. When

placing the input on the canvas it initializes to 1-bit. This number of bits can be increased in the

Attribute Table.

• The output pin (green circle in a circle) is used to observe output from a gate. The output pin

toggles in real time as long as the simulation is enabled from the menu bar Simulate > Simulate

enabled Explorer Pane: The list of wiring, gates, multiplexers, etc... that are available for digital design in Logisim. Please note not all items are allowed to be used in every project. Attribute Table: Gives detailed attributes of digital design components (e.g., AND, OR, XOR gates).

The attribute table allows you to alter the number of inputs/outputs that a digital design component. Canvas: The canvas is the area for you to create your digital circuits. In the canvas area you may simulate your circuits while designing in real time.

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The Main Trainer Kit:

Figure 3: KL-300 Trainer Kit

1. Dual VC Power Supply (1) Voltage range : +5V, 1.5A; -5V, 0.3A;

2. Adjustable DC Power Supply (1) Voltage range : +1.5V~+15V

(2) Maximum current output : 0.5A

3. Standard Frequency (1) Frequency : 1MHz, 60Hz, 1Hz

(2) Accuracy : ±0.01% (1MHz)

(3) Fan out : 10 TTL load

4. Clock Signal Generator (1) Frequency : 1Hz-1MHz (6 ranges)

a. 1Hz ~ 10Hz d. 1KHz~10KHz

b. 10Hz ~ 100Hz e. 10KHz~100KHz

c. 100Hz ~ 1KHz f . 100KHz~1MHz

(2) Fan out : 10 TTL load

5. Data Switch (1) 8-bit DIP switchx2, 16-bit TTL level output

(2) Toggle switchx4, each with DEBOUNCE circuit

(3) Fan out : 10 TTL load

6. Pulser Switch (1) 2 sets of independent control output

(2) Each set with Q, output, pulse width > 5ms

(3) Each set of switch with DEBOUNCE circuit

(4) Fanout : 10 TTL load

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7. Line Signal Generator (1) Frequency : 50/60Hz

(2) Output voltage : 6Vrms

(3) With overload protection

8. Thumbwheel Switch Two-digit, BCD code output, common point input

9. Logic Indicator (1) 16 sets of independent LED indicates high and low

logic state

(2) Input Impedence : 100KΩ

10. Digital Display (1) 4 sets of independent 7-segment LED display

(2) With BCD, 7-segment decoder/driver and DP input

(3) Input with 8-4-2-1 code

11. Logic Probe (1) TTL and CMOS level

(2) 5mm LED displays

(3) "Lo" and "Hi" LED display low and high logic state

respectively

12. Speaker 8W, 0.25W speaker with driver circuit 13. Breadboar 1680 tie-point breadboard on top panel can be

easily put

into and taken off.

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Integrated Circuits:

An integrated circuit (also referred to as an IC, a chip, or a microchip) is a

set of electronic circuits on one small plate ("chip") of semiconductor

material, on which thousands or millions of tiny resistors, capacitors, and

transistors are fabricated. The chip is packaged in a plastic holder with pins

which are numbered anti-clockwise around the IC starting near the notch or

dot. Figure 4 shows the numbering for 16-pin ICs, and the principle is the

same for all sizes.

Figure 4: Pin numbering of 16-pin IC.

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Datasheets:

Datasheets are available to describe the functions and properties of ICs. You can

get the datasheet of any IC using the number written on its plastic holder.

ICs may contain different number of Gates on it. For example DM7408 datasheet

would provide figure 4 and more information about the properties of these Quad 2-

Input AND Gates.

Figure 5: Connection diagram of DM7408 IC.

A logic family of digital integrated circuit devices is a group of electronic logic

gates constructed using one of several different designs, usually with compatible

logic levels and power supply characteristics within a family. Two main classes of

these families will be used in this lab, which are TTL and CMOS.

Figure 6 shows the circuit of TTL AND gate while figure 7 shows the circuit of

CMOS AND gate.

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Figure 6: TTL AND gate. Figure 7: CMOS AND gate.

Breadboard: The breadboard has 8 sets of rows, consisting of 20 holes that are horizontally

interconnected, and groups of columns, consisting of 5 holes that are vertically

interconnected. The rows and columns are used to hold chips and wires, and interconnect

them. The connection pattern used in the breadboard is shown in figure 8.

Figure 8: Breadboard.

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The top and bottom rows can be used to distribute +5V DC and ground to the ICs.

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.

Good wiring Bad wiring

Logic Switches: The logic switches, are used to provide logic 0 output (ground) and logic 1 output

(VCC).

Floating input:

A "floating" input is one that is not "tied" to anything. The usual “tie-ing” is either

a pull-up resistor to the VCC or a pull-down resistor to the ground. Either of these

connections establishes a known potential at the input.

Without either, the input potential is indeterminable - so it is “floating”. Floating

inputs are recognized as bad practice.

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Logic Indicators and Current Limiting Resistors: In this lab, we will measure the output of the logic gate using an LED. Notice that

limiting current into an LED is very important. As we know there is a

specification for diodes and LEDs called the characteristic forward voltage

(usually between 1.5-4V for LEDs). You must reach the characteristic forward

voltage to turn 'on' the diode or LED, but as you exceed the characteristic forward

voltage, the LED's resistance quickly drops off. Therefore, the LED will begin to

draw a bunch of current and in some cases, burn out. A resistor is used in series

with the LED to keep the current at a specific level called the characteristic

forward current.

There are two configurations for LED connection:

Common Cathode: The LED will turn ON at logic 1 and OFF at logic 0.

Common Anode: The LED will turn OFF at logic 1 and ON at logic 0.

See figure 9.

Figure 9: LED connections.