Digital Electronics
Josiah Smith
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Course Introduction
This course is rigorous and nationally accredited.
Digital Electronics studies electrical circuits that
manipulate digital signals. Digital signals are very
different than analog signals in that digital signals have
two discreet voltages or logic levels. Almost any
device today uses digital signals to process information.
This course will explore sequential logic, engineering
standards, and combinational logic. Students will work
with electrical circuits, and will utilize their
interpersonal skills, creative abilities and their prior
knowledge of the engineering design process.
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Personal Page
My name is Josiah Smith. I currently
attend Parkland High school as a junior. I am very
active in the Boy Scout program and also with my
church youth group. I also enjoy playing my
trumpet. I am involved in the school concert
band, jazz ensemble, pit orchestra and marching
band as well. I have been enrolled in the Project
Lead the Way course since freshman year. I have
taken both Intro to Engineering Design as well as
Principles of Engineering. I also took a class
sponsored by my school entitled Innovation and
Invention. Another class I participated in was
sponsored by Air Products called Explorer Post. I
have also earned both the electronics and
electricity merit badge in boy scouts.
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Unit 1: Digital and Analog
Fundamentals
Unit 1 is focused on the basics of electrical engineering and
design. Students will learn about components of circuits as well
as how to interpret measurements in a circuit. They will also
learn the basic measurements used in circuits as well. Students
will also learn about data sheets, schematics, transistortransistor logic and combinational logic gates.
1.1 Foundations and the
Board Game Counter
1.3 Introduction to Digital
1.2 Introduction to Analog
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1.1 Foundations and the Board
Game Counter
In this lesson, students will learn the basics of combinational and
sequential logic by assembling and analyzing the Game Board
Counter. This is a game that emulates a die. Students will also
learn safety, scientific and engineering notation, component
identification, and proper soldering techniques.
General Safety
Soldering
Engineers Notation
Game Board Counter
Electronic Components
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General Safety
The First order of business in section 1.1 is safety.
Electronics has many risks associated with it including:
Electrocution, burns, chemical damage, and even
simple wounds from components. We also learned
what causes the danger like increased current, hot
soldering irons, sharp components, smoke from
soldering or melting, and more. We learned how to
prevent these by using simple rules such as avoiding
baggy clothing or jewelry, avoiding damp areas, and
wear safety goggles!
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Engineers Notation
Engineer’s notation is used to shorten
long numbers with many digits. For
example, would you rather write
.000001 seconds or 1 microsecond?
One thing to keep in mind is that the
engineer’s notation only uses powers
of three to shorten numbers. So in the
previous example:
.000001 = 1 x 10 -6 = 1 microsecond
The prefixes used are shown in the
table to the right.
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Electronic Components
Electrolytic Capacitors
Multimeter
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Unit 1
In this section, we learned how to
identify all types of electronic
components such as resistors,
capacitors, LEDs, Integrated Circuits,
and more. We also learned how to
read the value of resistors and
capacitors. Most resistors have a series
of colored bands that help a user
determine its resistance. There are
many types of capacitors which all have
different methods of reading the
capacitance. We also learned how to
measure values with a multimeter.
Unit 2
Unit 3
Unit 4
Soldering
Soldering uses a tin and lead mixture to
melt and adhere to a printed circuit
board (PCB)as well as an electronic
component by heating the solder to 361°
F using a soldering iron. We learned
how to solder using correct techniques
such as tinning. We also learn the most
common mistakes of soldering such as:
Too much solder, too little solder, solder
bridge or a lifted trace pad. We also
learned how to safety handle a soldering
iron before testing out soldering on
some testing components.
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Game Board Counter
The Game Board Counter is a
simply electronic die that uses 7
LEDs to display the value of each
roll. In this circuit, there is an
analog section, a sequential logic
section, a combinational logic
section , and the LEDs. This
circuit also includes a switch, a
button, 7 LEDs, 10 resistors, 3
capacitors, 6 Integrated circuits
(ICs), 6 IC sockets, and one
battery pack.
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1.2 Introduction to Analog
This section will teach students basic circuit theory,
circuit simulation , breadboarding, digital and
analog signals. Students will also learn how the
game board counter works by using simulation.
Electron Theory
Breadboarding
Voltage, Current, and
Resistance
Digital and Analog Signals
Measuring Digital Signals
Series and
Parallel Circuits
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555 Timer
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Electron Theory
Electricity is the flow of electrons.
An element is determined by the
amount of electrons in an atom’s
outermost shell or its valence
electrons. The lower the valence
electrons, the more conductive an
element is because those few
valence electrons can more easily
be moved into a flow. Generally
elements with valence electrons
of 1-2 are conductors, 3-6 are
semi-conductors, and 7-8 are
insulators.
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Voltage, Current, and Resistance
Voltage is the electrical force that causes
current to flow in a circuit. This is
measured in volts. Current is the flow of
electrical charge through an electronic
circuit. The direction of a current is
opposite to electron flow. Current is
measured in amperes (amps). Resistance
is a measure of opposition to current flow.
It is measured in Ohms. Ohm’s law
defines the relationship between these
three measurements and is defined as V=I
x R or voltage = current x resistance.
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Parallel and Series Circuits
There are two different types of circuits. In a series
circuit, components are connected end-to-end and
there is only one path for current to flow. In a series
circuit, the current through every component is equal
and the resistances of each component add to equal
the total resistance. The sum of the voltages equals
the total voltage in a series circuit which is called
Kirchhoff’s Voltage Law. In a parallel circuit, both end
of components are connected together and there are
multiple paths for current to flow. The voltage across
every component is equal and the total resistance is
equal to the reciprocal of the sum of the reciprocal of
the resistance at each component. The sum of the
current is equal to total current which is called
Kirchhoff’s current law.
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Series Circuit
Parallel Circuit
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Breadboarding
A breadboard is a reusable platform for
temporarily built electronic circuits. A
breadboard is used by putting the leads
of electronic components into the holes
that are arranged in a grid pattern. A
series of metal strips connect rows of
holes. Breadboarding is helpful because
it takes less time and money and also
allows designers to see how the circuit
functions and adjust the circuit easily if
changes need to be made.
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Analog and Digital Signals
There are two types of electrical signals.
One is analog and the other is digital. Analog
signals are continuous, have an infinite range
of values, and have more exact values.
Digital signals are discrete, have a finite
range of values, are less exact than analog,
and are easier to work with. Digital signals
also have a logic high and a logic low. Logic
high is generally 5v and logic low is generally
0v. There is a level in between that is an
invalid logic level that has no meaning.
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Analog Signal
Digital Signal
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Measuring Digital Signals
There are different parts of a digital signal.
The Amplitude for digital signals is always
5V. The period is the time it take s for a
periodic signal to repeat. The frequency is
the number of cycles per second. The time
high is the time the signal is high or at 5V.
The Time low is the time the signal is low or
at 0V. The Duty Cycle is the percent of the
period that is Time High. The Rising edge is
the 0-to-1 transition of the signal. The
falling edge is a 1-to-0 transition of the
signal. Digital signals can be measured by
using an oscilloscope.
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Digital Signal
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555 Timer
A 555 timer is an 8-pin IC that is
capable of producing time delays
or oscillators. There is basically a
general circuit that all 555 timers
use. The components that affect
the 555 timer are two resistors
(Ra and Rb) as well as a capacitor.
There are formulas to calculate
the period, frequency and duty
cycle of a 555 timer output.
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1.3 Introduction to Digital
In this lesson, students will learn the basics of combinational
and sequential logic as well as further examining and
analyzing the Game Board Counter through simulation.
Students will also further be introduced to IC and
datasheets.
Combinational Logic
Integrated Circuits
Sequential Logic
IC Datasheets
Game Board Counter
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Combinational Logic
Combinational logic has one or more
inputs and one or more outputs. The
outputs are determined by the inputs
at that moment. Combinational logic
uses AOI logic. AOI stands for And,
Or, and Invert. An AND gate is a gate
that requires all true inputs to output
true. An OR requires one true input to
output true. An INVERTER gate
outputs the opposite of the input. All
logic gates have truth tables that
define all the possible inputs and
outputs of a gate.
Combinational Logic Schematic
OR gate truth table
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Sequential Logic
Sequential Logic has one or more
inputs and one or more outputs
just like combinational logic. The
difference is that in sequential
logic, the output is affected by the
current inputs as well as past
inputs. Sequential Logic also
utilizes memory or flip-flops and
clocks. Sequential logic uses these
flip flops in conjunction with each
other to create circuits such as a
binary counter or the game board
counter.
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Flip flop used in Game
Board Counter
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Game Board Counter
In the game board counter, the
first section is an Analog section
that produces square waves that
decrease in frequency and
eventually stop. That signal is
sent to the Sequential Logic
Section which goes through a
binary count of 1 to 6 on every
clock pulse then repeats. Those
signals are then sent to the
combinational logic which
encodes the binary count into the
die’s seven dots.
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Illustrative depiction of game board counter
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Integrated Circuits
All logic gates are built into Integrated Circuits
(ICs). There two main types of technology for
circuits: transistor-transistor logic (TTL) which is
faster but less energy efficient and
Complementary Metal Oxide Semiconductor
(CMOS) which uses less power and is slower.
There are also many types of integrations which
are the amount of gates per IC. There are two
main two main types of package styles as well.
They are Through-Hole Technology (THT) which is
only used for student use today and Surface
Mount Technology (SMT) which is used in almost
all electronics because of its smaller size.
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THT IC
SMT IC
Unit 2
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IC Datasheets
IC Datasheets are information sheets
containing the general description and
function, schematic, function table,
recommended operating conditions,
electrical characteristics, switching
characteristics, and physical dimensions
of an IC. These are sometimes included
with the IC and other times are found
online.
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Unit 2: Combination Logic
Unit 2 delves deeper into the Combinational Logic aspect of digital electronics. Students will use
concepts from Unit 1 and the new concepts of Unit 2 to create various design projects. Required
for these projects include the use of truth tables, logic expressions, Boolean Algebra, and
Karnaugh mapping to implement AOI, NOR, and NAND logic circuits. These circuits will be
demonstrated through physical breadboarding, computer design software, and the
Programmable Logic Device (FLD). Students also will learn the basics of XOR, XNOR, and binary
adder components. Binary, Octal, and Hexadecimal number systems will also be utilized in this
unit.
2.1 Introduction to AOI Logic
2.4 Specific Combinational Logic Circuits & Misc.
2.2 Introduction to NAND/NOR
Logic
2.5 Programmable Logic: Combinational
2.3 Date of Birth Project
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2.1 Introduction to
Combinational Logic
Unit 2.1 highlights the combinational logic portion of digital electronics.
Students will build upon their knowledge and learn new techniques and
concept which will build up to the Majority Vote project including truth
tables, AOI Logic, and simplification methods. Students will also learn about
the Computer Design Software and utilize it.
Binary Numbers & Conversions
AOL Implementation & Analysis
Truth Tables & Logic Expressions
Boolean Algebra & DeMorgan’s Theorems
AOI Logic
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Binary Numbers & Conversions
Humans understand and utilize
the decimal or base 10 number
system. In this system, each
digit represents a multiple of
ten. Computers and machines
understand the binary or base
2 number system. In this
system, every digit represents a
multiple of 2. Converting
between the two is essential to
learn.
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Converting from Binary to
Decimal System
Conversion from Decimal to
Binary System
Unit 2
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Truth Tables & Logic Expressions
Truth Tables display all possible
inputs and their corresponding
the outputs to show the
function of a certain gate. The
amount of outputs is
proportional to the number of
inputs. There are 2^x outputs
where x is the number of
inputs. From this truth table, a
logic expression can be derived.
A logic expression shows all
sets of inputs that will display a
positive, “1”, output.
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AOI Logic
AOI Logic stand for AND, OR, and
Inverter logic. This takes the truth table
and logic expressions and creates
working circuits from them. There are
these various gates used in this form of
circuitry. They output either positive or
negative based on whether or not the
inputs fit the criteria. For example, an
AND gate will only output positive when
all inputs are positive. An OR gate will
output positive when at least one input
is positive. An Inverter will output the
opposite of the input.
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AND Gate
Inverter
Gate
OR Gate
Unit 2
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AOI Implementation & Analysis
There are two forms of AOI Logic, Sum
of Products, and Product of Sums. One
or the other is generally used based
upon the efficiency. It is important to
be able to convert between a logic
expression and a circuit. This is
discussed in this section. Essentially, if
there is a “+” sign in the logic
expression, it corresponds with an OR
gate and if there is a “x” sign , it
corresponds with an AND gate. If a term
is, not-ed, an Inverter gate is used.
Example of Analysis of Logic Circuit
F2  A B C D  B C D  A B
Example of an implemented logic expression
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Boolean Algebra & DeMorgan’s
Theorems
Often times, when a logic
expression is taken from a
truth table it can be
simplified to create a
smaller, more efficient.
Boolean Algebra is a
algebraic method to shorten
expressions using the
Theorems shown. DeMorgan
added to these making more
simplification possible.
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Majority Vote
Problem Statement: A system must be designed to eliminate
the unreliable paper ballots that resulted in an unacceptable
amount of over-votes and under-votes. This system must
record the outcome based on the votes of 4 members.
This project culminated most of the lessons taught in this unit. First, a
truth table was derived from the constraints and design statement. Then,
a logic expression was derived. This was left un-simplified and was made
into a circuit drawing and then a CDS circuit and was tested. Students
then returned to the logic expression and simplified it using Boolean
Algebra and built a CDs circuit based on that. The two circuits were then
compared to show how useful simplification really is.
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2.2 Introduction to NAND/NOR
Logic
This Unit expands upon unit 2.1 and adds efficiency to the
design process as well as the production faze by keeping costs
down. K-Mapping increases efficiency when simplifying logic
expressions . The new gates cut down the amount of ICs
needed. The Fireplace project culminated unit 2.1 and 2.2 and
also requires breadboarding for the final circuit.
Karnaugh Mapping
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Fireplace Project
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Karnaugh Mapping
Karnaugh Mapping, or K-mapping
is simply another method to
simplify logic expressions in a
more graphic and visual fashion.
K-mapping uses groups of positive
outputs to simplify expressions.
These groups consist of adjacent
1’s in the truth table that are then
converted to a logic expression.
This method is very effective and
sometimes more efficient then
Boolean Algebra.
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A simple K-Map example
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NAND/NOR Logic
Sometimes there is a more effective implementation than AOI logic. That’s where
NAND and NOR gates come in handy! A NAND gate is an inverted AND gate and a
NOR gate is an inverted OR gate. Sometimes NAND and NOR implementations
can utilize less Integrated Circuits (IC’s) and therefore be cheaper for the
production of circuits.
This compares the
equivalent AOI and
NAND circuit. The
NAND is more
efficient because it
only uses one IC.
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Fireplace Project
A company requires a
new system to monitor
their fireplaces because
their safety systems are
ineffective. There are
4 flames and a sensor for Diagram of Fireplace
each one. The emergency cut off valve should be
triggered whenever less than 3 sensors detect no flame
to ensure no gas is escaping. An indicator should be
activated whenever all of the sensors do not agree to
indicate there is a problem with the sensors.
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Fireplace Project (Cont.)
Final Circuit in CDS program
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This project culminated almost all of
the concepts learned previously in this
course. First the truth tables and logic
expressions were derived with KMapping. Then the two sections of
the circuit were constructed in the CDS
software to test its function. One
section used AOI logic and the other
used NOR logic. The circuit was finally
recreated on a breadboard.
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2.3 Introduction to Date of
Birth Project
The majority of unit 2.3 is the Date of Birth project along with
some lessons that help complete that project. Students will
learn how to utilize seven segment display and demonstrate
their usage in the Date of Birth project. This unit will again
culminate almost all prior knowledge both for review but also
because of their necessity.
Seven Segment Displays
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Date of Birth Project
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Seven Segment Displays
Seven segment displays are used
in everyday life almost everywhere.
A seven segment display is a set
of 7 LED’s combined in a pattern
That allows for the display of
Seven Segment Display
numbers and letters. There are
two types of seven segment displays: anode and cathode. The
difference involves whether ground or power determines the lit
position. Seven segment displays also use a clever method to
conserve power by quickly cycling between LED’s that must be so that
we observe all segments are on. In reality, only one segment remains
lit at a time.
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Date of Birth Project
The objective of this project is to display the
month, day, and year of one’s birth using one
7 segment display and 3 inputs. This is done
by splitting each segment of the display into a
different section of the circuit. In other
words, each segment has its own truth table
and logic expression. My birthday is 07-3197. First, the truth table and logic expressions
were derived using K-maping. Then the
circuits were creating including 2 NAND and 2
NOR circuits. This circuit later utilized the
programmable logic board.
Final CDS Circuit
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2.4 Specific Combinational Logic
Circuits & Misc.
This Unit is a transitional unit between combinational logic and
sequential logic. This is used to cover materials that do not fit in with
other topics such as various number systems , binary addition, and
Multiplexers and Demultiplexers. XOR and XNOR gates are also utilized
by student to increase efficiency of circuits when possible.
Octal & Hexadecimal Number Systems
Binary Addition
XOR/XNOR Logic
2’s Compliment Arithmetic
Multiplexer/Demultiplexer
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Octal & Hexadecimal Number
Systems
Graphic to describe conversions
between number systems
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Computers need an awful lot of data to
function at the capacity they do, and if
binary were solely used, computers
would be slow and full of glitches. That
is why the Octal (8) & Hexadecimal
(16)Number systems are helpful; they
compact long sequences of binary to
create 8, 16, 32, 64, 128, ect. bit systems.
So as with binary, converting between
the decimal, octal, and hexadecimal
number systems is necessary. Since
there are only 10 possible numbers to
use as digits, letters are needed for the
hexadecimal number system.
Unit 1
Unit 2
Unit 3
Unit 4
XOR/XNOR Logic
XOR and XNOR are two more
gates that are used to create
higher efficiency whenever
possible. The XOR gate is used
Example XOR Logic Circuit
to create “X-clusiveness”.
In the OR gate, at least one input must be active. In XOR not all
inputs can be to output a positive. XNOR is the opposite of XOR.
All positive outputs in the XOR gate will be negative in the XNOR
gate, and vice versa. This logic is commonly used to create
binary adders.
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Multiplexer / Demultiplexer
A multiplexer is a device that
allows for one source to have
many destinations. This is attained
by using a set of switches to
decide where the source . A
Demultipllexer does the opposite
of a Multiplexer. It takes multiple
sources and allows it to travel to
many destinations. The amount of
switches corresponds with how
many outputs/inputs there are for
that specific IC.
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Unit 1
Practical use of a Multiplexer
Unit 2
Unit 3
Unit 4
Binary Addition
Adding binary is similar to adding
decimal numbers but slightly different.
One has to keep in mind that the max
number in a given digit is 1, anything
above that must be carried to the next
digit. Binary can also be added within
circuits using half or full adders. Half
adders only have 2 inputs and 2
outputs and can only be used for the
last digit (least significant digit). The
Full adder has 3 inputs and 2 outputs
and can be strung together to add
large numbers.
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Example of an Adder
Circuit
Unit 2
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2’s Compliment Arithmetic
Example of Displaying the
number -5 in binary
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2’s Compliment Arithmetic is
needed when adding negative
binary numbers. In binary, a
negative sign cannot be placed
before a binary numeral. For this
reason this method is used to
switch between positive and
negative binary values. To switch
between positive and negative,
the individual digits must all be
changed to their opposite (ex. 1
to 0, 0 to 1). Then the new
numeral must be added to 1
using binary addition
Unit 1
Unit 2
Unit 3
Unit 4
2.5 Programmable Logic:
Combinational
This unit deals almost solely with the Programmable abilities of both
the Computer Design Software and the Field Programmable Gate
Array. The information learned in lessons will be culminated in the
Paper Jam project which will also use topics from throughout the
unit.
Programmable Logic Device
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Paper Jam Project
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Programmable Logic Device
In previous projects, if one wanted to use
actual hardware to display a project, the
breadboard must be completed using all the
individual components. With a
Programmable Logic Device, CDS circuits can
be exported to the board so that hardly any
hardware is needed to be built to see the
physical results of the circuit. This feature
was utilized with the Date of Birth Project as
it was exported to the board to display the
birth date on its 7-segment display.
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Unit 2
Programmable Logic Device
Unit 3
Unit 4
Paper Jam Project
Visual Representation of Truth
Table
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This project required the designing of a
circuit that detected paper jams in a
copier. It utilized 3 switches that the
paper would activate. When 2 adjacent
switches are active, an LED and Buzzer
must be activated. When the jam is
cleared, the LED must turn off but the
buzzer should remain on until a clear
switch is pressed. This project is an
introduction to sequential logic with the
clear function as well as a demonstration
of the Programmable Logic Device.
Unit 1
Unit 2
Unit 3
Unit 4
Unit 3: Sequential Logic
This Unit will cover all the basics of sequential logic.. Sequential logic differs from
combinational logic in that it includes a memory portion. This unit will cover flip flops,
latches, counters, state machines and more. The projects in this unit utilize not only
the new information covered, but also combinational logic and breadboarding learned
in previous chapters. This unit few individual lessons and projects due to the complex
nature of each. Therefore there will be no sub-unit slides for this unit.
3.1 Latches & Flip Flops
Flip Flops
7 Segment Display Driver
The 74LS93
Latches
Flip Flop Applications
3.4 State Machines
3.3 Synchronous Counters
State Machines
Synchronous Counters
3.2 Asynchronous Counters
Asynchronous counters
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Now Serving Project
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Flip Flops
Flip Flops are critical to Sequential Logic and
provide the memory element to distinguish
it from combinational logic. Flip flops have
essentially two types of inputs, the actual
data input and the clock input. The output
of flip flops change on either the rising or
falling edge of a clock pulse based on the
data input. There are two types of flip
flops: D and J/K. In a D flip flop the output
(Q) copies the input D on the corresponding
clock edge. In a J/K, two inputs dictate
whether the output (Q) toggles, is set to
high, is cleared to low or does not change.
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D Flip Flop
J/K Flip Flop
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Latches
A Latch has an Enable input
(EN) which, when active, holds
the current output. The
enable function disregards
whatever the D input is
reading. In other words, the
EN input on a Latch is level
sensitive, and on a flip flop the
clock is edge sensitive.
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D-Latch
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Flip Flop Applications
An example of a shift register
The function of a Data
Synchronizer
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Flip Flops have many applications
including an event detector. An event
detector holds a signal until the event
that changed the signal is addressed.
A data synchronizer is used to hold
individual inputs until the correct
time, to make sure all inputs are
timed in synch. A frequency divider
can divide an input frequency by
multiples of 2. A shift register is a
group of flip flops that shift values
from one flip flop to the next for
every clock pulse.
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Asynchronous Counters
By connecting flip flops together, a counter can be made. The flip flops are
connected so that the clock is either connected to the Q or Q’ depending on
whether the clock is an up or down counter. The amount of values that can be
displayed is equal to 2 to the power of the number of flip flops. For example, if
there are 3 flip flops, 8 values could be displayed. Upper and lower limits can
also be set using a little combinational logic and the clear and preset options.
Asynchronous Counter
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Seven Segment Driver
The 74LS47N IC can take the input from a binary counter and output what is necessary to display
the value on a seven segment display. This combined with some resistors is very useful to
counters
Counter using the Seven Segment Driver
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The 74LS93
This IC is an Asynchronous MSI counter or a 4-Bit ripple counter. It is called a ripple counter
because there is a slight timing delay due to the clock being connected only two the first flip-flop.
This IC allows a 4-Bit counter in one package but includes some limitations. These include no
lower limit and no down count option.
A Simple Circuit using the 74LS93
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Synchronous Counters
Synchronous counters
accomplish the same thing
that Asynchronous counters
do but have a few
differences. One is that each
flip flop is individually
clocked and therefore there
is no ripple effect.
Synchronous counters do
require more logic than
Asynchronous ones though.
A 3-Bit Synchronous Counter
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MSI Gates
The 74LS163 is a 4-Bit Synchronous Counter that has an up count, a preloadable count start, a synchronous load, a synchronous clear, two enable
inputs, and a carry out signal. The 74LS193 is similar to the 163 but also
has down counting, a Borrow-Out signal, and asynchronous load and clear.
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Now Serving Project
This project was designed to
utilize previous knowledge of
counters to create a deli counter,
that is a counter with a range of
0-99. For this to occur, two
counters are needed, one counter
in the ones digit and one for the
tens digit. First, the circuit was
built in Multisim and then
exported to the DLB. This
counter also included a next
button to advance the count and
also a reset button to set the
count back to 0.
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The Active Now Serving Circuit
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State Machines
A state machine is a synchronous sequential circuit, consisting of a sequential logic
section and a combinational logic section, whose outputs and internal flip-flops
progress through a predictable sequence of states in response to a clock and other
input signals. State machines can be visualized using a state graph, which is essentially
a truth table but with a more graphic representation. A state machine has an input
combinational logic section, a memory section, and an output combinational logic
section. This state machine was used in a project to display the last 4 digits of our
phone number.
A State Graph
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Toll Booth Project
This project uses knowledge of state machines and combinational logic as well as sequential logic.
The goal is to create a toll booth arm that moves up and down when the corresponding switch is
pressed and displays whether the gate is open or closed using an LED. This project was first layed
out using a state machine and then transferred into Multisim. The finished circuit was then
exported to the DLB. Some breadboarding was completed to allow a connection between the
programmed board and the VEX toll booth arm.
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