EWB practical workbook
Post on 20-May-2015
20135 Views
Preview:
DESCRIPTION
Transcript
Practical Workbook
Logic Design amp Switching Theory I
Name _____________________________ Year __________ Batch ____________ Roll No _____________________________ Group No ____________________________ Department ____________________________
Dept of Computer amp Information Systems Engineering NED University of Engineering amp Technology
Karachi ndash 75270 Pakistan
Practical Workbook
Logic Design amp Switching Theory I
Prepared By M Anwar Ali Khan (Asst Professor) amp Muhammad Mazher Alam (Ex - Asst Professor) Revised By Maria Waqas (Lecturer)
Second Edition
Fourth Reprint ndash 2010
Dept of Computer amp Information Systems Engineering NED University of Engineering amp Technology
Karachi ndash 75270 Pakistan
THE BITS AND PIECES PART CIRCUIT
SIGN WHAT IT DOES
Supplies a voltage which drives an electric current round the circuit from the positive (+) terminal of the battery to its negative (ndash) terminal Voltage is measured in volts (V) and current in amperes (A)
Allows current to flow through it easily because it is made of copper which is a good electrical conductor Insulators like PVC (polyvinyl chloride - a plastic) and enamel are used to cover connecting wires
Connects terminal A to terminal B or C ie it is a change-over switch
Reduces the current in a circuit because of its resistance The colored bands give the resistance in ohms
When light falls on it its resistance becomes small in the dark its resistance is high
3
PART CIRCUIT SIGN
WHAT IT DOES
Stores electricity the greater the capaci-tance the more does it store Capacitance values are measured in microfarads shortened to μF or less correctly to mfd On a capacitor 01 μF may be marked as l mfd and 001μF as 10n The greatest voltage it can stand is also shown eg 30V
Stores electricity values usually larger than 1μF Greatest voltage marked on it Must be connected the correct way round
Varies the capacitance in a circuit by mov-ing one set of metal plates in or out of a fixed set when the spindle is rotated The sets of plates are separated by sheets of an insulator (also called a dielectric)
Changes electric currents into sound
Changes radio waves into electric currents
Lets current flow in one direction but not in the other When it conducts light is emit-ted Must have a current limiting resistor in series with it The cathode lead is nearest the lsquoflatrsquo and may be shorter than the anode lead (but this is not always so) The arrow on the sign shows the conducting direction
4
PART CIRCUIT SIGN
WHAT IT DOES
Amplifies small currents into much larger copies Acts as a very fast switch It must be correctly connected with a positive voltage to the collector
Transistors diodes resistors and capacitors are connected together on a tiny lsquochiprsquo of silicon (sand is mostly silicon oxide) to give any desired circuit eg a multistage amplifier an astable bistable or monostable multivibrator a counter a logic gate for a computer several stages of a TRF (tuned radio frequency) radio
They must be correctly connected Pin 1 is next to the lsquotagrsquo in the can type and on the dil type it is identified from the lsquonotchrsquo or lsquosmall dotrsquo on the case CMOS lsquochipsrsquo (standing for Complementary Metal Oxide Semiconductors and pronounced lsquosee-mossrsquo) need special care
PRECAUTIONS WITH CMOS INTEGRATED CIRCUITS Damage occurs if static charges build up on input pins when for example they touch insulating materials (eg clothes plastic pen) in warm dry conditions 1 Keep the IC in the carrier in which it is supplied until it is inserted in the circuit 2 Do not finger the pins or hold them in contact with an insulator 3 Connect all unused inputs of the IC to either the positive or the negative of the battery
depending on the circuit
5
BUILDING CIRCUITS
The circuit board shown above accepts ICs as well as separate components It has 47 rows of 5 interconnected sockets on each side of a central channel across which dil ICs can be fitted A wire inserted in a socket in a certain row becomes connected to wires in any of the other 4 sockets in that row by a metal strip under the board For example wires in sockets B5 C5 D5 E5 and F5 (shown in color in the diagram) are all joined Metal strips under the board connect the sockets A row of 40 interconnected sockets along the top of the board and a similar row along the bottom act as the positive and negative power supply rails (called lsquobus barsrsquo) Various makes of circuit board are available some with vertically mounting removable panels for supporting controls
6
1 To make a connection push about 1 cm of the bare end of a wire (025 to 085 mm diameter) straight into the socket (not at an angle) so that it is gripped by the metal strip under the board Do not use wires that are dirty or have kinked ends Only put one wire in each socket
Bend leads on resistors etc as shown before inserting them in the board
2 Bare the ends of connecting wire (PVC-covered tinned copper wire 06 mm diameter) by
removing the insulation (PVC) either with wire strippers or using a pair of blunt-nosed pliers and a pair of side cutters as shown With practice you should be able to judge just how much the side cutters have to be squeezed and pulled to remove the insulation without cutting the wire
3 lsquoJoinrsquo wires to the lsquolugsrsquo on the loudspeaker and variable capacitor using a small length of
2 mm bore plastic sleeving - as shown by 1 and 2
7
RESISTOR COLOUR CODE Resistor values are given in ohms (shortened to Ω the Greek letter lsquoomegarsquo) They are marked on the resistor using a color code Three colored bands are painted round the resistor Each color stands for a number To read the color code start at the 1st band it is nearest the end Sometimes it is not clear which is the 1st band because there is a 4th band of gold or silver near the other end These two colors are not used for the 1st band they give the accuracy of the resistor (gold is plusmn 5 and silver plusmn 10) so you should not have too much trouble deciding where to start The 1st band gives the first number the 2nd band gives the second number and the 3rd band tells how many zeroes come after the first two numbers
8
INTRODUCTION
Digital Logic Design is concerned with the interconnection among digital components and modules and the area of Switching Theory that can be identified between circuit design and system formulation Logic design is the base of any computer system as every digital system consists of different ICrsquoS and ICs contain a large number of interconnected digital circuits within a small package MSI devices provide digital function while LSI device cover a complete computer modules These circuitries are widely used in digital system like digital voltmeter frequency meter calculating machines telephone-switching system etc In this Practical Workbook laboratory sessions based on both combinational and sequential logic are covered First laboratory session gives an introduction to the basic logic gates and fundamentals of circuit building The second laboratory session covers a CAD software ndash Electronics Workbench (EWB) EWB is excellent simulation software where circuits can be designed and tested before physical implementation Various laboratory sessions of this workbook provide activities and exercises on EWB Next eight laboratory sessions are based on combinational logic Here various MSI circuits like adders converters multiplexers decoders encoders etc are designed Some of these laboratory sessions also include testing of MSI ICs Next four laboratory sessions help in exploring various designs based on sequential logic Here a variety of circuits are designed form the testing of basic flip-flop ICs to registers and different types of counters Last laboratory session demonstrates how digital hardware can be interfaced with a personal computer via parallel port and can be controlled by software All laboratory sessions of this workbook incorporate brief theoretical backgrounds as details may be covered in the respective theory classes Exercises activities are included with almost all the sessions for the students to practice Two appendices are also included in this workbook The first one provides pin diagrams for all the ICs required for the laboratory work provided in this workbook It will help the students in preparing the pin diagrams for the circuits Second appendix discusses a hardware debouncing circuit for mechanical switches as such switches are extensively used for input purpose in logic circuits
9
CONTENTS Lab Session No Object Page No
1 2 3 4 5 6 7 8 9
10
11
12
13
14
15
To study the logic gates in the following TTL ICs
7400 Quad 2-input NAND gate 7402 Quad 2-input NOR gate
7404 Hex inverter 7408 Quad 2-input AND gate 7432 Quad 2-input OR gate
Also implementing and testing the given circuit on a bread board Working with Electronics Workbench Designing Half and Full Adder Circuits Use of Karnaugh Map (SOP-Expression) method Designing a BCD Adder Designing of a 4 x 1 Multiplexer Experimenting with 74150 IC Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer Experimenting with 74138 IC Designing of a 4 x 2 Priority Encoder Experimenting with 74148 IC Designing an Odd Parity Generator and Checker for a 3-bit Data Driving a seven segment display using 7447 7448 driver IC Experimenting with different modes of JK-FF Designing sequential circuit for the given state diagram using D flip-flop Designing a modulus-5 asynchronous up-counter using JK-FF Experimenting with 74194 4-bit bidirectional universal shift register Experimenting with 74245 octal bus transceivers using parallel port PC interfacing Appendix A ndash Pin Diagrams of the ICs required for the laboratory sessions Appendix B ndash Debouncing circuitry for mechanical switches
13
17
19
22
28
30
34
38
42
45
48
50
54
56
59
66
69
11
Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 01 OBJECT
bull To study the logic gates in the following TTL ICs
i) 7400 Quad 2-input NAND gate ii) 7402 Quad 2-input NOR gate iii) 7404 Hex inverter iv) 7408 Quad 2-input AND gate v) 7432 Quad 2-input OR gate
bull Implementing and testing the given circuit on a bread board
COMPONENTS REQUIRED 1 Bread board 2 5 V - power supply 3 Multimeter 4 Logic probe 5 LEDs with resistors 6 Connecting wires 7 Switches (optional) 8 Following ICs and their datasheets
bull 7408 quad 2 input AND gate bull 7432 quad 2 input OR gate bull 7404 hex inverter bull 7400 quad 2 input NAND gate bull 7402 quad 2 input NOR gate
THEORY
Logic Gates
Logic gates are the fundamental building blocks of digital systems These devices are able to make decisions in the sense that they produce one output level when some combinations of input levels are present and a different output when other combinations are applied hence given the name Logic Gates The two levels produced by digital circuitry are referred to variously as HIGH and LOW TRUE and FALSE ON and OFF or simply 1 and 0 There are only three basic gates AND OR and NOT The other gates are merely combinations of these basic gates Logic gates can be interconnected to perform a variety of logical operations This interconnection of gates to achieve prescribed outcomes is called logic design
1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
13
Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when
the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as AF =
4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF =
5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as BAF +=
All the above gates have one output and two or more inputs except the NOT gate which has only one input
PROCEDURE FOR TESTING THE LOGIC GATES IN GIVEN ICs
1 Set the power supply to 5V With the help of a multimeter check the voltage at the output knobs of the power supply
2 Connect wires long enough to reach the breadboard with the two knobs of the power supply Again using multimeter check voltage at the non-connected end of the wires
3 Insert the 7408 quad 2 input AND gate IC on to the bread board and make supply and ground connections by joining 5V wire to pin 14 and 0V wire to pin 7
4 Consult ICrsquos internal connection diagram for input and output pins of the first AND gate Connect input pins to logic 0 (0V) and observe the output using LED or logic probe You can also connect switches at the input lines to facilitate toggling between 1 and 0
5 Try different combinations of logic levels at the two inputs Again observe the output 6 Repeat the last two steps for all other gates of the same IC Record the observations 7 Repeat this procedure for all other ICs
OBSERVATIONS
Gate Input A Input B Expected Output Observed Output
AND
0 0 0 1 1 0 1 1
OR
0 0 0 1 1 0 1 1
NOT 0 - 1 -
NAND
0 0 0 1 1 0 1 1
14
Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
NOR
0 0 0 1 1 0 1 1
DATA SHEETS
Figure 11
15
Logic Design amp Switching Theory 1 Lab Session 01 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
16
GIVEN CIRCUIT
Figure 12
PROCEDURE FOR IMPLEMENTATION OF THE GIVEN CIRCUIT 1 Set the power supply 2 Insert ICs on the bread board and make their supply and ground connections 3 As given in the logic diagram make connections using wires and gates in the ICs 4 Apply different combinations at the three inputs and observe the output OBSERVATIONS Logic expression for the given logic diagram __________________________________
A B C Expected Output Observed Output 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1
Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 02
OBJECT
Working with Electronics Workbench
ELECTRONICS WORKBENCH - EWB Electronics Workbench is a computer aided design tool that provides you with all the components and instruments necessary to create board-level designs It has complete mixed analog and digital simulation and graphical waveform analysis allowing you to design your circuit and then analyze it using different simulated instruments and analysis options It is fully integrated and interactive thus you can change your circuits quickly allowing fast and repeated what-if analysis Electronics Workbench provides the following kind of components bull Sources parts bin (AC voltage source Vcc source ground battery etc) bull Basic parts bin (resistors capacitors transformers switches etc) bull Diodes parts bin bull Transistors parts bin bull Analog ICs parts bin (op-amps etc) bull Mixed ICs parts bin (ADCs DACs 555 timers etc) bull Digital ICs parts bin (AND OR adders multiplexers etc) bull Indicators parts bin (voltmeter ammeter probe displays etc) bull Controls parts bin (voltage differentiator multiplier etc) bull Instruments parts bin (multimeter oscilloscope function generator etc) bull Miscellaneous parts bin (write data textbox etc)
o Write data This component allows you to save simulation results as an ASCII file o Text Box Use this to add descriptive text anywhere in a circuit
ACTIVITY
Design circuit for the logic expression )( CBDCABAF ++=
Procedure 1 From Logic Gates Parts Bin Drag and drop the required logic gates on the design
area Use Component Properties dialog box to customize these gates 2 Connect the terminal of these gates according to the given expression Use additional
connectors form the Basic Parts Bin if you want to connect more than wire at a single node
3 Drag and drop a probe from Indicators Parts Bin Use Component Properties dialog box to customize the color and other properties of the probe Connect this probe at the output terminal of the circuit to indicate results
4 Select four switches form Basic Parts Bin Specify the key that controls the switch by typing its name in the Value tab of the Component Properties dialog box For
17
Logic Design amp Switching Theory 1 Lab Session 02 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
18
example if you want the switch to close or open when digit lsquo1rsquo is pressed type 1 in the Value tab then click OK Assign different keys to all the switches
5 Connect the output terminals of these switches to each of the four inputs A B C and D of the circuit
6 Drag and drop Vcc and Ground form the Sources Parts Bin 7 Connect Vcc terminal to one end and Ground terminal to the other end of all the
switches 8 Label the circuit properly using text boxes found in the miscellaneous parts bin 9 Run the circuit using the Activate Simulation switch Use the keys you have assigned
to the switches to toggle them between Vcc and Ground connections thus providing 1 or 0 respectively to the inputs Record the results as indicated by the probe for all possible combinations of 1s and 0s at the inputs
EWB Circuit
Figure 21
Observations
A B C D Expected Output Observed Output 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
Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 03
OBJECT
Designing Half and Full Adder Circuits COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets
bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7486 Quad 2-input XOR Gate
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY Half Adder A combination circuit that performs the addition of two bits without accounting for the previous carry is called half adder It needs two binary inputs and two binary outputs The input variables designate the augend and addend bits The output variables produce the sum and carry The simplified sum of product expressions for a half adder are
yxyxyxS oplus=+= yxC =
Figure 31 Circuit diagram for Half Adder
19
Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
bles produce the sum and carry The simplified sum of product expressions for a half adder are
Full Adder
A combinational circuit that performs the addition of three input bits It consist of three inputs and two outputs Two of the input variables represent the two significant bits to be added The third input represents the carry from the previous lower significant position The output varia
zyxzyxzyxzyxzyxS oplusoplus=+++= yxzyxzyzxxyC )( +oplus=++=
Figure 32 Circuit diagram for Full Adder
efer to laboratory session 01 for procedure) and record the observations in the following ta
alf Adde ull Adder Inputs u
IMPLEMENTATION AND OBSERVATIONS
Implement the half adder and full adder circuits on a bread board (prepare the pin diagram (use appendix A) and r
bles H r F
Inputs Outputs Outp ts x y Carry Su Carry Sum m x y z 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 1 1 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1
20
Logic Design amp Switching Theory 1 Lab Session 03 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
at of your designed circuit Attach hardcopy of the output form electronic workbench
at of your designed circuit Attach hardcopy of the output form lectronic workbench here
ACTIVITY
1 Simulate half adder circuit using Electronics Workbench Compare the results of simulation with thhere
2 Design a full subtractor circuit and simulate it using Electronics Workbench Compare the results of simulation with the
21
Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 04 OBJECT
Use of Karnaugh Map (SOP-Expression) method GIVEN LOGIC EXPRESSION
F (A B C D) = sum ( 0 1 2 4 5 6 8 9 12 13 14 ) COMPONENTS AND APPARATUS REQUIRED 1 Digital ICs and their Datasheets
bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7404 Hex Inverter
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches PROCEDURE 1 Use Karnaugh map to reduce the given function 2 Draw the circuit diagram for the obtained reduced function 3 Implement the reduced circuit using digital ICs on a bread board (prepare the pin
diagram (use appendix A) and refer to laboratory session 01 for procedure) and record the observations
REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP F
CD
AB DC
DC DC
DC
BA0 1 3 2
BA4 5 7 6
BA12 13 15 14
BA8 9 11 10
Reduced form of the given logic expression is __________________________________
22
Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
LOGIC DIAGRAM (REDUCED FORM) OBSERVATIONS
A B C D Output 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
RESULT The reduced form (SOP Expression) of the given logic function is
____________________________________________________________
The observation table reflects the given logic function
23
Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
ACTIVITY 1 Using Electronics Workbench derive a truth table and logic circuit for the following logic expression
BAAF +=
Procedure 1 From the Instruments Parts Bin drag and drop Logic Converter on the design area 2 Double click the Logic Converter to reveal Logic Converter dialog box This dialog
box shows various conversion options between truth table logic expression and logic circuit
3 Enter the given logic expression in the edit box found at the end of the dialog box Use lsquo to represent invert of a variable For example A is written as Arsquo
4 Click the Boolean Expression to Truth Table button The truth table appears in the logic converters display
5 Now click the Boolean Expression to Circuit button This creates the logic circuit for the given expression in the design area Label the diagram if needed
Resulting Logic Circuit For the given expression the final circuit will look like
Figure 41
24
Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
ACTIVITY 2
Using Electronics Workbench find a simplified logic expression and circuit for the following truth table
A B C Output 0 0 0 1 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1
Procedure 1 Click three input channels from A to H across the top of the logic converter The
display area below the terminals fills up with the necessary combinations of ones and zeros to fulfill the input conditions The values in the output column on the right are initially set to 0
2 Edit the output column to specify the desired output for each input condition To change an output value select it and type a new value 1 0 or x An x indicates a donrsquot care condition
3 To convert this truth table to a Boolean expression click the Truth Table to Boolean Expression button The Boolean expression will be displayed at the bottom of the logic converter
4 Simplify the expression by clicking the Simplify button 5 Now click the Boolean Expression to Circuit button This creates the logic circuit for
the given expression in the design area Resulting Logic Circuit For the given truth table the final simplified circuit will look like
Figure 42
25
Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
ACTIVITY 3
Using Electronics Workbench find the logic expression and truth table for the following logic circuit
Figure 43
Procedure 1 Attach the input terminals of the logic converter to up to four input points in the
circuit 2 Connect the single output of the circuit to the output terminal on the logic converter
icon 3 Click the Circuit to Truth Table button The truth table appears in the logic
converters display 4 To convert this truth table to a Boolean expression click the Truth Table to Boolean
Expression button The Boolean expression will be displayed at the bottom of the logic converter
Resulting Logic Expression Logic Expression for the given circuit is found to be _____________________________
26
Logic Design amp Switching Theory 1 Lab Session 04 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
27
For activities 1 2 and 3 attach hardcopy of the output (truth table logic expression and logic circuit) form electronic workbench here
Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 05 Lab Session 05 OBJECT OBJECT
Designing a BCD Adder Designing a BCD Adder COMPONENTS AND APPARATUS REQUIRED COMPONENTS AND APPARATUS REQUIRED
1 Following ICs and their Datasheets 1 Following ICs and their Datasheets bull 7408 Quad 2-input AND Gate bull 7408 Quad 2-input AND Gate bull 7432 Quad 2-input OR Gate bull 7432 Quad 2-input OR Gate bull 7483 4-bit Binary Adder bull 7483 4-bit Binary Adder
2 Digital Trainer DT-01 or the following components 2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors (100 Ω) Connecting wires Switches (100 Ω) Connecting wires Switches
THEORY THEORY
A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD A BCD Adder is a combinational circuit that adds two BCD digits in parallel and produces a sum digit also in BCD
A4 A3 A2 A1 B4 B3 B2 B1
7483-BCD ADDER
Cout (C4 ) Z4 Z3 Z2 Z1 Cin(C0)
A4 A3 A2 A1 B4 B3 B2 B1
7483-BCD ADDER
Cout
(C4 ) Z4 Z3 Z2 Z1 Cin(C0)
Figure 51 BCD Adder Circuit
28
Logic Design amp Switching Theory 1 Lab Session 05 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
29
A BCD adder must include the correction logic in its internal construction The two BCD digits together with the input carry are first added using a 4-bit binary adder to produce the binary sum If no output carry is generated and the binary sum is less than or equal to 9 then the corresponding BCD sum is identical and therefore no conversion is needed When the output carry is equal to 1 or the binary sum is greater than 9 then a binary 0110 is added to the binary sum through another 4-bit binary adder If Cout is the carry output and Z4Z3Z2Z1 is the binary sum form the first 4-bit binary adder then the following equation indicates the condition when a binary 0110 is to be added
C = COUT + Z4Z2 + Z4Z3 IMPLEMENTATION AND OBSERVATIONS Implement the BCD adder circuit according to figure 51 on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure) A BCD adder has nine input bits (two BCD digits and a carry bit) which can result in a total of 512 combinations of which 312 inputs are donrsquot care Since it is a very lengthy procedure to record results for 200 valid input combinations therefore for simplicity just record results for any eight combinations in the following table
Input Carry
BCD Digit 1 BCD Digit 2 Carry Output
BCD Sum A4 A3 A2 A1 B4 B3 B2 B1 Z4 Z3 Z2 Z1
Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 06
OBJECT
bull Designing of a 4 x 1 Multiplexer bull Experimenting with 74150 IC
COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets
bull 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74150 16 x 1 MUX
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY
Multiplexers A digital data Multiplexer (MUX) is a combinational circuit having several data inputs and a single output A set of data-select inputs is used to control which of the data inputs is routed to the single output A multiplexer is also called a data selector because of this ability to select which data input is connected o the output Normally there are 2n input lines and n selection lines whose bit combination determine which input is selected DESIGN OF A 4 x 1 MULTIPLEXER A 4 x 1 multiplexer is capable of selecting one of four data inputs (see figure 61) The 2-bit binary number at the data select inputs S1 and S0 specifies which of the four data inputs is to be routed to the output Since there are two data select inputs therefore they can select 22 = 4 different data inputs lines
S0 S1 D0 D1
D2 D3
Data-select Inputs Output
Data Inputs
Figure 61 Block Diagram of a 4 x1 Multiplexer
30
Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Figure 62 Circuit Diagram for 4 x 1 Multiplexer
Implementation and Observations
Implement the 4 x 1 Multiplexer circuit (figure 62) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table For each data select combination specify the switch number as well as the binary value present on that selected switch
S1 S0 Output 0 0 0 1 1 0 1 1
TESTING OF 74150 - 16 x 1 MUX
The 74150 IC has sixteen data inputs and four data-selection lines Function of various pins of this IC is described below
bull E0 through E15 Data input lines
31
Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull A B C D Data select lines with D being the MSB bull W Active low output line bull Grsquo Active low enable line bull VCC and GND Supply connections lines
Circuit Diagram
Figure 63 Pin connections of 74150 for selecting E0
Testing Procedure
bull Make connections as shown in the circuit diagram bull Apply different data (1 or 0) at data inputs that are labeled as E0 to E15 Only
connection for E0 is shown is the figure for simplicity bull Select the data input E0 with the help of data selectors A B C and D bull Observe the output which shows the complement of the data from E0 bull Select all the sixteen data inputs one by one and record your observations in the
following table
32
Logic Design amp Switching Theory 1 lab Session 06 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
33
Observations
Grsquo D C B A W Grsquo D C B A W 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 1 0 1 0 0 0 0 1 1 0 1 0 1 1 0 0 1 0 0 0 1 1 0 0 0 0 1 0 1 0 1 1 0 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 1 1 1 1
ACTIVITY 1 Consider 4x1 Multiplexer Draw the output wave-form for the following data inputs
(E0 E1 E2 E3) and select lines A B (B being the MSB) Output is W
E3 E2 E1 E0 A B
W
2 Using the 4 x 1 MUX designed in this laboratory session implement the following logical function F (A B C) = Σ (0147)
Show your working and input connections in the following block diagram according to the circuit you have implemented
4 x 1 MUX
S0 S1
Output D0
D1
D2
D3
Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 07
OBJECT
bull Designing of a 2 x 4 Decoder 1 x 4 Demultiplexer bull Experimenting with 74138 IC
COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets
bull 7408 Quad 2-input or 7411 Triple 3-input AND Gates bull 7404 Hex Inverter bull 74138 3 x 8 Decoder
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches THEORY
Decoder A Decoder is a combinational circuit that converts binary information form n input lines to a maximum of 2n unique output lines In practical applications decoders are often used for selecting one of several devices
Demultiplexer A decoder with an enable input can function as a Demultiplexer A Demultiplexer (DMUX) id a circuit that receives information on a single line and transmits this information on one of 2n possible output lines The selection of a specific output line is controlled by the bit values of n selection lines DESIGN OF A 2 x 4 DECODER 1 x 4 DEMULTIPLEXER A 2 x 4 decoder is capable of selecting one of four output lines (see figure 71 (a)) The 2-bit binary number at the data inputs S1 and S0 specifies which of the four data inputs is to be selected If we add an enable pin and use it as an input line then this decoder can be converted to a 1 x 4 Demultiplexer where S1 and S0 will select a line to which data input is to be routed (see figure 71 (b))
Select S0 S0 Inputs
S1 D0 D1
D2
D3
Enable (a) Block Diagram of a 2 x 4 Decoder
Figure 71
S1 D0 D1
D2
D3
Inputs
Data Input (b) Block Diagram of a 1 x 4 Demulptiplexer
34
Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
Implementation and Observations Implement the 2 x 4 Decoder 1 x 4 Demultiplexer circuit (figure 72) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table
Enable Data Input S1 S0 D0 D1 D2 D3
0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1
TESTING OF 74138 3 x 8 Decoder The 74138 IC has three inputs and eight output lines It has three enable inputs and for the IC to function all three inputs need to be enabled Function of various pins of this IC is described below
35
Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
bull Y0 through Y7 Active low data outputs bull A B C Input select lines with C being the MSB bull G1 Active high enable Input bull G2Arsquo and G2Brsquo Active low enable Inputs bull VCC and GND Supply connections lines Circuit Diagram
Figure 73 Pin connections of 74138
Testing Procedure
bull Make connections as shown in the circuit diagram bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table
Observations
C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1
36
Logic Design amp Switching Theory 1 Lab Session 07 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
37
ACTIVITY ACTIVITY 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if 1 What will be the binary values at the outputs Y0 through Y7 of 74138 if
bull All three enable pins are connected to ground bull All three enable pins are connected to ground __________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________
bull All three enable pins are connected to VCC bull All three enable pins are connected to VCC _______________________________________________________________________________________________________________________________________________________________________________________________________________
_______________________________________________________________________________________________________________________________________________________________________________________________________________
2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer 2 Show connections for 74138 in order to use it as a 1 x 8 Demultiplexer
3 Consider a 2 x 4 Decoder with two enable inputs (one active high - G and one active low ndash Grsquo) Draw the output wave-forms for D0 D1 D2 and D3 if the two select inputs are A and B (B being the MSB) All outputs are active low
Grsquo
G
A B
D0 D1 D2
D3
Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 08 OBJECT
bull Designing of a 4 x 2 Priority Encoder bull Experimenting with 74148 IC
COMPONENTS AND APPARATUS REQUIRED
1 Following ICs and their Datasheets
bull 7408 Quad 2-input or 7421 Dual 4-input AND Gates bull 7432 Quad 2-input OR Gates bull 7404 Hex Inverter bull 74148 Encoder
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY
Encoder An Encoder is a digital function that produces a reverse operation from that of a decoder An Encoder has 2n (or less) input lines and n output lines The output lines generate the binary code for the 2n input variables Priority Encoder
A simple encoder may produce an erroneous output if more than one of its inputs is high A Priority Encoder is one that responds to just one input among those that may be simultaneously high in accordance with some priority system The most common priority system is based on the relative magnitudes of the inputs whichever decimal input is largest is the one that is encoded
DESIGN OF A 4 x 2 Priority Encoder
The following equations represent the outputs of a 4 x 2 priority encoder 32 DDA +=
321 DDDB += As can be seen from the equations that input D0 which has a binary code 00 is not used in any equation A binary code 00 at the output indicates two conditions Either D0 is selected or no input is selected In order to differentiate these two conditions we will provide an additional output Z to indicate if at least one of the inputs is a 1 The equation for Z will be
4321 DDDDZ = If Z is 0 then the binary code 00 at the output indicates that D0 is selected and if Z is 1 then it indicates that no input line is selected
38
Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
it (figure 81) on a bread board (prepare the to laboratory session 01 for implementation
Implementation a Implement the 4 x 2 Priority Encoder circu
ram (use appendix A) and refer
nd Observations
pin diagprocedure) and record the observations in the following table
D3 D2 D1 D0 A B 0 0 0 1 0 0 1 x 0 1 x x 1 x x x
TESTING OF 74148 8 x 3 Octal Priority Encoder
imal digits There are nine of which three represents
ing any of the inputs is high
then it shows that line 0 is selected and if e inputs selected E0 and GS
cannot be in the same state provided that E1 is enabled
The 74148 is a priority encoder with active-Low input for dec
input) and five output linesinputs lines (including an enablethe binary code for the octal digit Function of various pins of this IC is described below
bull 0 through 7 Active low data inputs representing the octal digits A2 A1 A0 Active low output lines representing the binary code bullbull E1 Active low enable Input bull E0 Active low output indicating none of the inputs is high bull GS Active low output indicatbull VCC and GND Supply connections lines Therefore if GS A2 A1 and A0 are all low
then it shows that none of thE0 A2 A1 and A0 are all low
39
Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Circuit Diagram
Figure 82 Pin connections of 74148
Testing Procedure bull Make connections as sho
binations of 1s and 0s at data inputs d record your observations in the following table
GS E0
wn in the circuit diagram bull Apply different combull Observe the output an Observations
0 1 2 3 4 5 6 7 A2 A1 A0 1 1 1 1 1 1 1 1 x x x x x x x 0 x x x x x x 0 1 x x x x x 0 1 1 x x x x 0 1 1 1 x x x 0 1 1 1 1 x x 0 1 1 1 1 1 x 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1
40
Logic Design amp Switching Theory 1 Lab Session 08 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
41
CTIVITY
Cascade the following two 74148 8 x 3 Priority Encoders to form 16 x 4 Priority
A 1
Encoder
Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `
Lab Session 09 OBJECT
Designing an Odd Parity Generator and Checker for a 3-bit Data COMPONENTS AND APPARATUS REQUIRED
1 Following ICs and their Datasheets
bull 7486 Quad 2-input Exclusive-OR Gates bull 7404 Hex Inverter
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY
Parity Generator When binary data is transmitted and processed it is ndash as are all electrical signals ndash susceptible to noise that can either alter or distort its contents 1s may be effectively changed to 0s and 0s to 1s To overcome this problem one or more bits are often added to the data as an aid in detecting errors caused by noise The most common of these is a Parity bit that signifies whether the total number of 1s in a code group is odd or even In an Odd Parity system the parity bit is made 0 or 1 as necessary to make the total number 1s odd (counting the parity bit itself) In an Even Parity system the parity bit is chosen to make the total number of 1s even Table 91 shows how parity bits would be added to BCD code group in both systems
Decimal BCD Value Parity Bit ABCD Odd Parity Even Parity
0 0000 1 0 1 0001 0 1 2 0010 0 1 3 0011 1 0 4 0100 0 1 5 0101 1 0 6 0110 1 0 7 0111 0 1 8 1000 0 1 9 1001 1 0
Table 91 Odd and Even Parity in BCD
When digital data is received a parity checking circuit generates an error signal if the total number of 1s is odd in an even parity system or if it is even in an odd parity system Parity check always detects a single error (one bit change from 0 to 1 or 1 to 0) but may not detect
42
Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering ` two or more errors Odd parity is used more often than even parity because even parity does not detect a situation where all 0s are created due to short circuit or other fault condition DESIGN OF A 3-BIT ODD PARITY GENERATOR AND CHECKER Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows P = x oplus y Ο z or P = x Ο y oplus z Since the IC available is 7486 which is quad 2input XOR IC therefore we will convert XNOR also to XOR
P = x oplus y Ο z
P = ( x oplus y ) Ο z Since for even number of variables ______
XOR = XNOR Therefore ___________ _________
P = ( x oplus y ) oplus z = x oplus y oplus z This logical expression can be implemented with two XOR gates and an inverter (see figure 91)
Figure 91 Circuit Diagram for a 3-bit Parity Generator
The 3-bit message and the parity bit are transmitted to their destination where they are applied to a Parity Checker Circuit An error occurs during transmission if the parity of the four bits received is even since the binary information transmitted was originally odd The output C of the parity checker should be a 1 when an error occurs ie when the number of 1s in the four inputs is even Therefore the function C can be expressed as
C = x Ο y Ο z Ο P
Using the same logic applied for the conversion of the equation of P
PzyxC oplusoplusoplus= This logical expression can be implemented with three XOR gates and an inverter (see figure 92)
43
Logic Design amp Switching Theory 1 Lab Session 09 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering `
44
Figure 92 Circuit Diagram for a 3-bit Parity Checker Implementation and Observations Implement the 3-bit Parity Generator and Checker circuits (figure 91 and 92) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table
x y z P x y z P C x y z P C 0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 1 1 0 0 1 0 1 0 0 0 1 0 1 0 1 0 0 1 1 0 0 1 1 1 0 1 1 1 0 0 0 1 0 0 1 1 0 0 1 0 1 0 1 0 1 1 1 0 1 1 1 0 0 1 1 0 1 1 1 0 1 1 1 0 1 1 1 1 1 1 1
Odd Parity Generation Odd Parity Check ACTIVITY 1 Try using the parity checker of figure 92 as 3-bit parity generator Write the details here
_____________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________ _______________________________________________________________________ ______________________________________________________________________________________________________________________________________________
Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 10 OBJECT
Driving a seven segment display using 7447 7448 driver IC COMPONENTS AND APPARATUS REQUIRED
1 Following ICs and their Datasheets
bull Seven Segment Displays (Common Anode Common Cathode) bull 7447 7448 BCD to Seven Segment Driver
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY Seven Segment Displays A Seven Segment Display consists of seven light-emitting segments The segments are designated by letters a through g (see figure 101) By illuminating various combinations of segments the numerals 0 through 9 can be displayed Seven Segment Displays are commonly constructed with light-emitting diodes (LEDs) and with liquid-crystal displays (LCDs) LEDs generally provide greater illumination levels but require much greater power than LCDs An LED display can be a common-anode type or common cathode type In common anode type a high voltage is applied at the common terminal of the display and low voltage is applied at a segmentrsquos terminal for illumination In the common-cathode type a low voltage is applied at the common terminal of the display and high voltage is applied at a segmentrsquos terminal for illumination
Figure 101 Seven Segment Display
a f b g
e c d
7447 7448 BCD to Seven Segment Driver 7447 7448 IC is particularly used to drive Seven Segment Its input is a BCD number and output drives a seven segment display 7447 is used to drive common-anode displays whereas 7448 is used to drive common cathode displays 7447 7448 is a 16 pin IC Function of various pins of these ICs is described below
bull A B C D Inputs representing BCD digits (D being the MSB)
45
Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull OA through OG Outputs to drive segments a through g of the display (Active low
in 7447 and active high in 7448) bull RBI Ripple Blanking Input Turns off all the segments if kept low provided that LT
is kept high and all other inputs (A B C D BI) are kept low Should be kept high otherwise
bull BI RBO Wire-AND logic serving as a Blanking Input and or Ripple Blanking Output
o BI Turns off all the segments if low o RBO Goes to a low level (response condition) along with other outputs when
RBI and inputs A B C and D are low with LT input at high level bull LT Lamp Test input Tests whether all segments are working or not Illuminates all
segments if kept low provided that BI is kept high Should be kept high otherwise bull VCC and GND Supply connections lines CIRCUIT DIAGRAM
Figure 102 Circuit diagram for 7447driving a common-anode display
IMPLEMENTATION AND OBSERVATIONS
bull Make connections as shown in the circuit diagram (refer to laboratory session 01 for implementation procedure)
bull Apply different combinations of 1s and 0s at data inputs bull Observe the output and record your observations in the following table
46
Logic Design amp Switching Theory 1 Lab Session 10 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
47
Decimal Digit
BCD Inputs Seven Segment Outputs D C B A a b c d e f g
0 0 0 0 0 1 0 0 0 1 2 0 0 1 0 3 0 0 1 1 4 0 1 0 0 5 0 1 0 1 6 0 1 1 0 7 0 1 1 1 8 1 0 0 0 9 1 0 0 1
ACTIVITY 1 Perform the Lamp Test for the designed circuit and write your observations
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
2 How can you use 7447 IC to drive a common-cathode display
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
3 What symbols appear in the seven segment display if inputs DCBA are
DCBA Symbol
1010
1011
1100
1101
1110
1111
Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
48
Lab Session 11 OBJECT
Testing different modes of JK-FF COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets
bull 7473 7476 JK Flip-Flop 2 Digital Trainer DT-01 or the following components
Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY
Flip-Flop A flip-flop circuit can maintain a binary state indefinitely (as long as the power is delivered to the circuit) until directed by an input signal to switch states The major differences among various types of flip-flops are in the number of inputs they possess and in the manner in which the inputs affect the binary state
JK Flip-Flop JK flip flop is an edge triggered device A typical JK flip flop has three inputs J K and a clock input The flip-flop can be either positive or negative edge triggered The output Q is available in complemented form as well Beside the usual inputs and output most of the flip-flop IC also possess two asynchronous inputs namely Preset and Clear These inputs are usually active low If used Preset and Clear inputs keep the flip-flop in set and reset state respectively irrespective of the other inputs Both of these inputs cannot be used simultaneously otherwise they will bring the flip-flop in unstable state
Figure 111 Symbol for JK flip-flop
(a) positive-edge triggering (b) active low Preset (PR) and Clear (CLR) with positive-edge triggering
(c) active low Preset (PR) and Clear (CLR) with negative-edge triggering
Logic Design amp Switching Theory 1 Lab Session 11 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
49
TESTING OF 7473 7476 DUAL JK FLIP-FLOP
Both the ICs 7473 and 7476 are similar in functionality except for one difference The flip-flops in 7473 have only one type of active low asynchronous input which is the Clear input whereas the flip-flops in 7476 have both Preset and Clear inputs Both these ICs have negative edge triggered flip-flops
Circuit Diagram
Figure 112 Pin connections of 7476
Testing Procedure
bull Make connections as shown in the circuit diagram (figure 112) bull Apply different combinations of 1s and 0s at J and K inputs bull Observe the output and record your observations in the following table
Observations
J
K Q
0 0 0 1 1 0 1 1
ACTIVITY
1 Observe the output Q of JK flip-flop if the clock input is connected to VCC or GND instead of a clock source Write your observations here __________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________
Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
50
Lab Session 12 OBJECT
Designing sequential circuit for the given state diagram using D flip-flop GIVEN STATE DIAGRAM
00
11
Figure 121 State Diagram COMPONENTS AND APPARATUS REQUIRED 1 Following ICs and their Datasheets
bull 7474 D Flip-Flop bull ICs of basic gates (AND OR NOT XOR etc) as required
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY
Sequential Circuits In Sequential Circuits the output not only depends on the present inputs but also on previous states of the circuit These circuits use memory elements (latches flip-flops) and the binary information stored in the memory elements at any given time defines the state of the sequential circuit Analysis of a Sequential Circuit The behavior of a sequential circuit is determined from the inputs the outputs and the states of its flip-flops Both the outputs and next state are a function of the inputs and the
10
01
00 11 10
00
00 11 10 00
Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
51
present state The analysis of a sequential circuit form a state diagram comprises of the following bull Selecting a particular flip-flop to design the circuit bull Obtaining state table from the state diagram bull Finding input equations for the selected flip-flop bull Finding state equations (not required for the construction of circuit) bull Implementing the circuit using selected flip-flops and their input equations ANALYZING THE GIVEN STATE DIAGRAM D Flip-Flop D flip-flop is also called transparent flip-flop as it simply transfers the input data to the output For our design we require the graphical symbol and excitation table of D flip-flop (see figure 122)
Qt Qt+1 T 0 0 0 0 1 1 1 0 0 1 1 1
(b) Excitation table of D Flip-Flop
(a) Graphical Symbol
Figure 122 Characteristic equation of D flip-flop is Q(t+1) = D State Table The given state diagram has four states so we will need two D flip-flops (FF-0 FF-1) Form state table form the given state diagram and record the results in the following table
Present State Input Next State Output Input to FF-0 D0
Input to FF-1 D1 Q1t Q0t x Q1(t+1) Q0(t+1) z
Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
52
Input Equations Using Karnaugh map the input equations D0 and D1 for the two flip-flops can be found
D0 D1 Q0x
Q1
_ _ Q0x
_ Q0x
Q0x
_ Q0x
Q0x
Q1
_ _ Q0x
_ Q0x
Q0x
_ Q0x
_ Q1
_ Q1
Q1
Q1
D0 = _________________ D1 = _________________
State Equations Using the characteristic equation of D flip-flop we can find the state equations Q0(t+1) and Q1(t+1) for the to flip flops Q0(t+1) = _______________________ Q1(t+1) = _______________________ _______________________ _______________________ _______________________ _______________________ Circuit Diagram
Logic Design amp Switching Theory 1 Lab Session 12 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
53
Implementation Procedure and Observations
1 Implement the circuit using digital ICs on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for procedure)
2 Make the clear inputs of the flip-flops low (to clear the flip-flops) The flip-flops will remain in clear state as long as the clear inputs are connected to low level
3 Connect output Q0 and the clock pulse to an oscilloscope 4 Apply 0 to the input x 5 Now make the clear inputs to high 6 Observe the waveform for the first 5 clock pulses and record it 7 Repeat steps 2 to 6 keeping x=1 in step 4 this time 8 Repeat steps 2 to 7 this time connecting Q1 instead of Q0 to the oscilloscope in step
3 Record your observations (Keep frequency of the clock pulse low (eg1Hz) so that the output waveforms can be observed easily)
1 2 3 4 5 Clock Pulse
Output Waveform for Q0 when x=0
Output Waveform for Q0 when x=1
Output Waveform for Q1 when x=0
Output Waveform for Q1 when x=1
Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 13 OBJECT
Designing a modulo-5 asynchronous up-counter using JK-FF COMPONENTS AND APPARATUS REQUIRED
1 Following ICs and their Datasheets
bull 7400 Quad 2-input or 7410 Triple 3-input NAND Gates bull 7476 7473 JK Flip-Flop
2 Digital Trainer DT-01 or the following components Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY
Digital Counters A digital counter is a set of flip-flops whose states change in response to pulses applied at the input to the counter The flip-flops are interconnected so that their combined state at any time is the binary equivalent of the total number of pulses that have occurred up to that time Every counter resets after a certain number of clock pulses Thus as it name implies a counter is used to count pulses An n stage counter can count up to a maximum of 2n states n is equal to the number of flip-flops required for the construction of counter
Modulus Counters The number of input pulses that causes a counter to reset to its initial count is called the modulus of the counter Thus the modulus equals to total number of distinct states (counts) including zero that a counter can store A binary counter with n stages is a modulo-2n (or mod-2n) counter The largest count a mod-N counter can achieve is N-1 ie a mod-N counter never reaches the binary number equal to its modulus N is always equal to or less than 2n Counters can be classified as bull Synchronous Counters which are clock driven All the flip-flops are driven by a
single clock bull Asynchronous Counters which are event driven Clock input is given to the first
flip-flop only Rest of the flip-flops are driven by their preceding flip-flops
DESIGN OF A MOD-5 ASYNCHRONOUS UP COUNTER The number of flip-flops required to construct a mod-5 counter is 3 because 5 should be less than or equal to 2n This counter will count from 0 to 4 a total of 5 distinct states Since a 3-stage counter can count up to 8 states at maximum a NAND gate is used to reset it after 5 clock pulses Figure 131 shows the logic diagram
54
Logic Design amp Switching Theory 1 Lab Session 13 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
55
Figure 131 A Mod-5 Asynchronous Up Counter
Implementation and Observations
Implement the mod-5 counter circuit (figure 131) on a bread board (prepare the pin diagram (use appendix A) and refer to laboratory session 01 for implementation procedure) and record the observations in the following table
Clock Pulse Q2 Q1 Q0
0 1 2 3 4 5 6 7
ACTIVITY
Draw the timing diagram for mod-5 counter designed in this laboratory session
Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 14 OBJECT
Experimenting with 74194 4-bit bidirectional universal shift register COMPONENTS AND APPARATUS REQUIRED
1 Following ICs and their Datasheets
bull 74194 4-bit bidirectional universal shift register 2 Digital Trainer DT-01 or the following components
Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY
Shift Registers
A Register is a set of flip-flops used to store binary data A register which is capable of shifting its binary information either to the right or left is called a shift register The logical configuration of a register consists of a chain of flip-flops connected in cascade with the output of one flip-flop connected to the input of next flip-flop All flip-flops receive a common clock pulse which causes the shift from one stage to the next
Bidirectional Shift Registers A bi-directional shift register is one whose bits can be shifted from left to right or from right to left
Universal Shift Registers A universal shift register is a bi-directional register whose input can be in either serial or parallel form and whose output can be in either serial or parallel form
74194 4-BIT BIDIRECTIONAL UNIVERSAL SHIFT REGISTER
The 74194 register provides parallel as well as serial loading in both directions Function of various pins of this IC is described below
bull A B C and D Active high inputs for parallel loading bull QA QB QC and QD Active high outputs bull S0 and S1 Active high mode control inputs The following table shows combinations
of S1 and S0 to enable various modes
S1 S0 Clock Action 0 0 x No change 0 1 uarr Shift right 1 0 uarr Shift left 1 1 uarr Parallel load
uarr shows the rising edge of the clock pulse
56
Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull SR Active high serial input for right shifting bull SL Active high serial input for left shifting bull CLR Active low input Clears all the flip-flops of the register if set to 0 should be
kept high otherwise bull CLK Clock input bull VCC and GND Supply connections lines Thus A B C and D are inputs for parallel loading whereas SR and SL are inputs for serial loading with right or left shifting respectively S1 and S0 are used to select the loading mode Circuit Diagram
Figure 141 Pin connections of 74194 Testing Procedure
bull Make connections as shown in the circuit diagram bull Observe the output for the input combinations given in the following table
57
Logic Design amp Switching Theory 1 Lab Session 14 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
58
Observations
S1 S0 SL SR A B C D QA QB QC QD 0 0 0 1 0 0 0 0 0 1 1 0 0 0 0 1 1 0 0 0 0 0 1 0 1 1 0 0 0 0 1 1 0 0 1 1 0 1 0 0 0 1 1 1 0 1 0 1 1 0 1 0 0 1 1 0 1 1 1 0 0 1 1 1 1 1 0 0 1 1 1 1
ACTIVITY 1 Show connections of 74194 to convert it into a ring counter with right shifting
Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Lab Session 15
OBJECT
Experimenting with 74245 octal bus transceivers using parallel port PC interfacing COMPONENTS AND APPARATUS REQUIRED 1 Parallel Port Connectors (DB-25) with Cable 2 Personal Computer with Windows 98 and TurboC Compiler Installed 3 Following ICs and their Datasheets
bull 74245 Octal Bus Transceivers with 3-State Outputs 4 Digital Trainer DT-01 or the following components
Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
THEORY
3-State Logic Sometimes it is necessary to isolate one part of circuit from the other part For this purpose some TTL ICs are designed with 3-state logic Such devices have three possible output states high low and high impedance The device can be put into high impedance state by a control signal applied to an appropriate pin When such a device is in high impedance state there is very high impedance at its output effectively isolating the device from whatever circuitry the output normally drives 74245 Octal Bus Transceivers A bus is any conducting path or set of paths having electrical connections to one or more devices 74245 octal bus transceivers are mainly used to control connectivity between two devices or circuits It also provides direction control for signal flow Function of various pin of this IC is given below
bull A1 through A8 Bus A bull B1 through B8 Bus B bull G΄ Active low enable input When high sets all the bus pins to high impedance state bull DIR Direction control for signal flow When set to high logic level transfers bus A
data to B bus When set to low logic level transfers bus B data to A bus bull VCC and GND Supply connections lines Serial and Parallel Port Connectors A Parallel Port can consist of only 25 pin port adapter called a DB-25 and a serial port can consist of either a 25 pin port adapter called a DB-25 or 9 pin adapter called a DB-9 port adapter Whether the port is a 9 pin or 25 pin it can accomplish all of the same tasks that serial port communications have been designed for
59
Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
60
Each adapter can be a male type connector with pins or a female type adapter with tiny holes Generally a PRINTER port (called LPT1) on the back of a computer is female type adapter and we need to use MALE DB-25 pin cable on it for PRINTER connection or for parallel LAPLINK cable And a COM port on the back of a computer is male for the serial ports but it may not necessarily be Parallel Port Connector ndash DB-25 The DB-25 connector (named for its B-size D-shaped shell and 25 pins) is practically ubiquitous in the electronics industry The DB-25 connector is used for a variety of purposes Two common applications are RS-232EIA-232 (serial) connections and the parallel printer interface on the IBM PC The DB-25 connector is also used for SCSI connections Normally the parallel port is used for output to a printer or other device It sends data 8-bits or one byte at a time in parallel The other lines available on the DB-25 connector are a combination of status lines control lines and ground lines The status and control lines are used for handshaking commands and feedback when we are talking to a printer
Figure 152 DB-25 Female Figure 151 DB-25 Male
Figure 153 Pin Layout for DB-25 As can be seen form figure 153 there are four types of pins in this connector
bull Data pins (8 pins - D0 to D7) Active high bidirectional lines
Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering bull Control pins (4 pins - C0 to C3) C0 C1 and C3 are active low whereas C2 is active
high These lines also are bidirectional bull Status pins (5 pins ndash S3 to S7) Only S7 is active low rest are active high input lines bull Ground pins (8 pins) Used as a reference signal for the low (below 05 volts) charge
Parallel Port Addresses A DB-25 connector at a parallel port has three address one for each kind of pins register data status and control The first or base address generally refers to data register Second address is for status register and the third one is for control register In Windows 98 the base address is usually found to be 278H 378H or 3BCH Now if 378H is the base address then it refers to the data register whereas addresses for status and control register are respectively 379H and 37AH For Windows 98 the base address can be found as follows 1 On your Desktop right-click on My Computer and select Properties 2 Click on the Device Manager tab and find LPT1 under Plug and Play BIOS 3 After selecting LPT1 click the Properties button 4 Next select the Resources tab and the address should then appear next to InputOutput
Range Accessing parallel port through C Language Programming There are multiple functions in C Language for accessing external ports The most commonly used are listed below
bull unsigned char inportb(int portid) inportb reads a byte from a hardware port
bull int inport(int portid) reads a word from a hardware port
bull void outportb(int portid unsigned char value) outputs a byte to a hardware port
bull void outport(int portid int value) outputs a word to a hardware port
portid refers to the port address whereas value refers to the data to be sent TESTING 74245 USING PARALLEL PORT PC INTERFACING At one end the parallel port connector will be connected to the PC via parallel port cable and another connector (to be plugged into the PC parallel port slot) At the other end it will be connected to the buffer IC 74245 Data lines of the connector will be used to transfer 8-bit data between the PC and the buffer Out of the 8-bits of 74245 4-bits will be used to enter data which will be displayed at the monitor through a C language
61
Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering program The remaining 4-bits will receive data from PC as entered by the user via keyboard
Circuit Diagram
Figure 154 Interface of 74245 to PC via Parallel Port
Procedure
1 Connect the DB-25 connector to the PC at one end and solder it to the circuit board at the other end
2 Connect various pins of the connector and 74245 according to the circuit diagram shown in figure 152
3 Using the functions listed in the previous section write a program in C language to operate various pins of the buffer The user interface of the program should provide option to the user whether to send or receive data from the port
4 Set DIR switch to 1 5 Try sending some data bits to the port The result should be displayed at the LEDs 6 Set DIR switch to 0 7 Set some binary 4-bit value through the switches Try reading it via parallel port
C Language Program
A program to access parallel port for data transfers
use header file include ltstdiohgt main program void main() define variable
62
Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering unsigned int data=0 char choice while(1) printing option menu clrscr() printf(This program will send or receive a BCD digit from the parallel portn) printf(nPress your choice numbern) printf(n1 Send Data) printf(n2 Receive Data) printf(n3 Exitn) choice = getch() sending entered digit to the port if(choice == 1) input BCD digit printf(nEnter BCD digit to be sent to the port) data = getche() masking the first four bits data = data amp 0x0f sending to the port outportb(0x378data) printf(nThe BCD digit c has been sent to the port data) printing on screen the data received from the port else if(choice == 2) receiving data from the port data = inportb(0x378) masking the last four bits data = data amp 0xf0 shifting first four bits to make them the last four bits datagtgt=4 printf(nThe BCD digit set at the port is c data) exit else if(choice == 3) break key pressed is not in the menu else printf(nEnter valid choice number) printf(nnPress any key to continue) getch()
63
Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
ACTIVITY 1 In the above circuit DIR and G΄ inputs are hardwired Connect them to status or
control pins of the parallel port connector and control their function through your software program Circuit Diagram Program Code ______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________
___________________________________________________________________________________________________________________________________________________
64
Logic Design amp Switching Theory 1 Lab Session 15 NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
65
_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________ _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________ _________________________________________________
Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Appendix A
PIN DIAGRAMS OF THE ICS REQUIRED FOR THE LABORATORY SESSIONS Consult the TTLIC data book for internal diagrams and electrical characteristics of these ICs 7400 Quad 2-Input NAND 7402 Quad 2-Input NOR
7404 Hex Inverter 7408 Quad 2-Input AND
7410 Triple 3-Input NAND 7411 Triple 3-Input AND
7421 Dual 4-Input AND 7432 Quad 2-Input OR
66
Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
BCD-to-Seven Segm 7448 BCD-to-Seven Segment 7447 ent
Decoder (15V OC) Decoder (2kΩ pull-up output)
7473 Dual JK Flip-Flop 7474 Dual D-Type Flip-Flop
7476 Dual JK Flop-Flop -Bit Binary Full Adder 7483 4 with Fast Carry
86 Quad 2-Inpu 74138 3-to-8 Line 74 t Exclusive OR Decoder Demultiplexer
67
Logic Design amp Switching Theory 1 Appendix A NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
68
74148 8-to-3 Line 16-to-1 Line Data
Priority Encoder 74150 Selector Multiplexer
74245 Oct nsceivers Universal Shift Register (PIPO) (3-State)
74194 4-Bit Bidirectional al Bus Tra
Logic Design amp Switching Theory 1 Appendix B NED University of Engineering amp Technology ndash Department of Computer amp Information Systems Engineering
Appendix B
DEBOUNCING CIRCUITRY FOR MECHANICAL SWITCHES Mechanical switches form the interface between human beings and computers or other digital systems For example a keyboard is a matrix of switches used to supply alphanumeric data to a computer Whatever the switch design it is a potential source of problems due to contact bounce The contact bounce creates a sense of narrow pulses when a switch is opened or closed An example of device whose operation would be adversely affected by contact bounce is a digital counter used to count the number of times a switch is depressed Eliminating the effects of contact bounce is called debouncing When data is entered into a computer via a keyboard a software debounce is often used This type of debouncing is a program that causes the computer to sample the switch terminal (ie to input data from it) many times in succession during the interval of time that contact bounce occurs If the data is sensed to be 1s (or 0s) for a specific number of consecutive samples then it is assumed that contact bounce has ended and the last value sensed is valid Hardware debouncing is the use of electronic circuitry to eliminate the effects of contact bounce There are numerous versions of such circuitry including those that use monostable multivibrators (one-shots) but the most straightforward is simply an RS latch Figure B1 shows the circuit When the switch is in position 1 R = 0 and S = 1 so the latch is set and the output (Q) is 1 When the switch is in position 0 R = 1and S = 0 so the latch is reset and the output is 0 When the switch is moved form one position to the other the latch changes state and bouncing occurs at either the R or the S input The bouncing does not affect the latch after it has change state An RS latch will remain set for example when its R input is 0 and its S input is alternately changed form 1 to 0
Figure B1 Use of RS latch to debounce a mechanical switch
69
- 01-ldst-Outer title
- Practical Workbook
- Logic Design amp Switching Theory I
- Dept of Computer amp Information Systems Engineering
- NED University of Engineering amp Technology
- Karachi ndash 75270 Pakistan
- 02-ldst-inner Title
- Practical Workbook
- Logic Design amp Switching Theory I
- Dept of Computer amp Information Systems Engineering
- NED University of Engineering amp Technology
- Karachi ndash 75270 Pakistan
- 03-ldst-general info
- 04-ldst-introduction
- 05-Table of Contents
- CONTENTS
- Lab Session No Object Page No
- 1
- Also implementing and testing the given circuit on a bread board
- Working with Electronics Workbench
- Driving a seven segment display using 7447 7448 driver IC
- Designing a modulus-5 asynchronous up-counter using JK-FF
- Experimenting with 74194 4-bit bidirectional universal shift register
- 13
- 06-ldst-Exp01
- Lab Session 01
- OBJECT
- 1 Bread board
- 2 5 V - power supply
- 3 Multimeter
- 4 Logic probe
- 5 LEDs with resistors
- 6 Connecting wires
- 8 Following ICs and their datasheets
- THEORY
- Logic Gates
- 1 The AND Gate ndash An AND gatersquos output is 1 if and only if all its inputs are 1 If A and B are two inputs to an AND gate then output F of the gate is given as F = AB
- 2 The OR Gate - An OR gatersquos output is 1 if at least one of its input is 1 If A and B are two inputs to an OR gate then output F of the gate is given as F = A+B
- 3 The NOT Gate (Inverter) ndash Its output is 1 when its input is 0 and its output is 0 when the input is 1 ie it complements a digital variable If A is the input to a NOT gate then output F of the gate is given as
- 4 The NAND Gate ndash Its output is 1 if at least one of its input is 0 This gate performs the same logic as an AND gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
- 5 The NOR Gate - The output of a NOR gate is 1 if and only if all its inputs are 0 This gate performs the same logic function as an OR gate followed by an inverter If A and B are two inputs to a NAND gate then output F of the gate is given as
- DATA SHEETS
- Logic expression for the given logic diagram __________________________________
- 07-ldst-exp02
- Working with Electronics Workbench
- 08-ldst-exp03
- Designing Half and Full Adder Circuits
- COMPONENTS AND APPARATUS REQUIRED
- 1 Following ICs and their Datasheets
- 7408 Quad 2-input AND Gate
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- Connecting wires Switches
- THEORY
- IMPLEMENTATION AND OBSERVATIONS
- 09-ldst-Exp04
- Lab Session 04
- 1 Digital ICs and their Datasheets
- 7408 Quad 2-input AND Gate
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- Connecting wires Switches
- PROCEDURE
- REDUCTION OF LOGIC EXPRESSION USING KARNAUGH MAP
- OBSERVATIONS
- RESULT
- 10-ldst-Exp05
- Lab Session 05
- 1 Following ICs and their Datasheets
- 7408 Quad 2-input AND Gate
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- (100 Ω) Connecting wires Switches
- THEORY
- IMPLEMENTATION AND OBSERVATIONS
- 11-ldst-Exp06
- OBJECT
- 1 Following ICs and their Datasheets
- 7408 Quad 2-input AND Gates or 7411 Triple 3-input AND Gates
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- Connecting wires Switches
- Figure 62 Circuit Diagram for 4 x 1 Multiplexer
- Implementation and Observations
- Circuit Diagram
- ACTIVITY
- 12-ldst-exp07
- 1 Following ICs and their Datasheets
- 7408 Quad 2-input or 7411 Triple 3-input AND Gates
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- Connecting wires Switches
- THEORY
- Figure 72 Circuit Diagram for 2 x 4 Decoder 1 x 4 Demultiplexer
- Implementation and Observations
- Circuit Diagram
- ACTIVITY
- 13-ldst-Exp08
- OBJECT
- 1 Following ICs and their Datasheets
- 7408 Quad 2-input or 7421 Dual 4-input AND Gates
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- Connecting wires Switches
- THEORY
- Figure 81 Circuit Diagram for 4 x 2 Priority Encoder
- Implementation and Observations
- Therefore if GS A2 A1 and A0 are all low then it shows that line 0 is selected and if E0 A2 A1 and A0 are all low then it shows that none of the inputs selected E0 and GS cannot be in the same state provided that E1 is enabled
- Circuit Diagram
- ACTIVITY
- 14-ldst-exp09
- OBJECT
- 1 Following ICs and their Datasheets
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- Connecting wires Switches
- THEORY
- Parity Generator
- Let x y and z be the three bits that constitute the message and are the input to the Odd Parity Generator Circuit Since it is an odd parity system the bit P is generated so as to make the total number of 1s odd (including P) The function P can be expressed as follows
- Figure 91 Circuit Diagram for a 3-bit Parity Generator
- C = x Ο y Ο z Ο P
- Implementation and Observations
- ACTIVITY
- 15-ldst-exp10
- Driving a seven segment display using 7447 7448 driver IC
- COMPONENTS AND APPARATUS REQUIRED
- 1 Following ICs and their Datasheets
- 7447 7448 BCD to Seven Segment Driver
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors Connecting wires Switches
- THEORY
- Seven Segment Displays
- CIRCUIT DIAGRAM
- Figure 102 Circuit diagram for 7447driving a common-anode display
- IMPLEMENTATION AND OBSERVATIONS
- Decimal Digit
- BCD Inputs
- Seven Segment Outputs
- D
- C
- B
- A
- a
- b
- c
- d
- e
- f
- g
- 0
- 0
- 0
- 0
- 0
- 1
- 0
- 0
- 0
- 1
- 2
- 0
- 0
- 1
- 0
- 3
- 0
- 0
- 1
- 1
- 4
- 0
- 1
- 0
- 0
- 5
- 0
- 1
- 0
- 1
- 6
- 0
- 1
- 1
- 0
- 7
- 0
- 1
- 1
- 1
- 8
- 1
- 0
- 0
- 0
- 9
- 1
- 0
- 0
- 1
- ACTIVITY
- 16-ldst-exp11
- Lab Session 11
- OBJECT
- COMPONENTS AND APPARATUS REQUIRED
- 1 Following ICs and their Datasheets
- 7473 7476 JK Flip-Flop
- 2 Digital Trainer DT-01 or the following components
- Bread board 5 V - Power Supply Multimeter Logic Probe LEDs with Resistors
- Connecting wires Switches
- THEORY
- Flip-Flop
- JK Flip-Flop
- Circuit Diagram
- Observations