1 chapter 1 introductory digital concepts. 2 chapter outline digital and analog quantities binary...
TRANSCRIPT
1
Chapter 1
Introductory Digital Concepts
2
Chapter Outline
• Digital and Analog Quantities• Binary Digits, Logic Levels, and Digital
Waveforms• Introduction to Basic Logic Operations• Basic Overview of Logic Functions• Fixed-Function Integrated Circuits• Programmable Logic Devices (PLDs)• Introduction to Test Instruments
3
Figure 1--1 Graph of an analog quantity (temperature versus time).
4
Figure 1--2 Sampled-value representation (quantization) of the analog quantity in Figure 1-1. Each value represented by a dot can be digitized by representing it as a digital code that consists of a series of 1s and 0s.
5
Digital Advantages
• Digital Data can be processed/transmitted more efficiently and reliably.
• Storage: can be stored more compactly and reproduced w/ greater accuracy and clarity.
6
Figure 1--3 A basic audio public address system.
Analog Electronic System
7
Figure 1--4 Basic principle of a CD player. Only one channel is shown.
System Using Digital and Analog Methods
8
Binary Digits
• Two digits in BINARY system, 1 and 0, called BIT (Binary digit)
• Positive Logic: HIGH=1, LOW=0
• Negative Logic: LOW=1, HIGH=0
• Code : Groups of bits to represent numbers, letters, symbols, instructions, etc.
9
Figure 1--5 Logic level ranges of voltage for a digital circuit.
Logic Levels
Voltages used to represent 1 and 0.
10
Figure 1--6 Ideal pulses.
Digital Waveforms
Figure 1--7 Nonideal pulse characteristics.
11
Frequency and Period
• Frequency (f) # cycles per sec or Hertz (Hz)
• Period (T) in seconds.
• f=1/T, T = 1/f
12
Figure 1--8 Examples of digital waveforms.
Periodic and Nonperiodic
13
Figure 1--9
Pulse Width and Duty Cycle
Duty Cycle = (tw/T)100 %
14
Figure 1--10 Example of a clock waveform synchronized with a waveform representation of a sequence of bits.
Digital Waveform Carries Binary Information
15
Figure 1--11 Example of a timing diagram.
16
Figure 1--12 Illustration of serial and parallel transfer of binary data. Only the data lines are shown.
Data Transfer
17
Figure 1--15 The basic logic operations and symbols.
Basic Logic Operations and Symbols
18
Figure 1--16 The NOT operation.
NOT Operation
19
Figure 1--17 The AND operation.
AND Operation
20
Figure 1--18 The OR operation.
OR Operation
21
Basic Logic Functions• Comparison Function• Arithmetic Functions• Code conversion function• Encoding function• Decoding function• Data selection function• Data storage function• Counting function
22
Figure 1--19 The comparison function.
Comparison Function
23
Figure 1--20 The addition function.
Arithmetic Function
24
Figure 1--21 An encoder used to encode a calculator keystroke into a binary code for storage or for calculation.
Code Conversion Function: Encoder
25
Figure 1--22 A decoder used to convert a special binary code into a 7-segment decimal readout.
Code Conversion Function: Decoder
26Figure 1--23 Illustration of a basic multiplexing/demultiplexing application.
Data Selection Function
27
Figure 1--24 Example of the operation of a 4-bit serial shift register. Each block represents one storage “cell” or flip-flop.
Data Storage Function
28
Figure 1--25 Example of the operation of a 4-bit parallel shift register.
Data Storage Function
29
Figure 1--26 Illustration of basic counter operation.
Counting Function
30
Figure 1--27 Cutaway view of one type of fixed-function IC package showing the chip mounted inside, with connection to input an output pins.
Fixed-Function Integrated Circuits
31
Figure 1--28 Examples of through-hole and surface-mounted devices. The DIP is larger than the SOIC with the same number of leads. This particular DIP is approximately 0.785 in. long, and the SOIC is approximately 0.385 in. long.
IC Packages
32
Figure 1--29 Examples of SMT package configurations.
33
Figure 1--30 Pin numbering for two standard types of IC packages. Top views are shown.
Pin Numbering
34
Integrated Circuit Technologies
• TTL
• ECL
• CMOS
• NMOS
• SSI and MSI use TTL or CMOS
• VLSI and ULSI use CMOS or NMOS
35
Programmable Logic Devices (PLD)
• Programmable logic devices can replace fixed-function logic - the major advantage is that the logic function of the PLD can be changed without rewiring.
• SPLD (Simple Programmable Logic Devices)
• CPLD (Complex Programmable Logic Devices)
36
Types of SPLD
• PAL (Programmable Array Logic)
• GAL (Generic Array Logic)
• PLA (Programmable Logic Array)
• PROM (Programmable Read-only Memory)
37
Figure 1--32 Typical CPLD packages.
CPLDs are made using 2 to 64 SPLDs
Types of CPLD
38
PLD programming
• Schematic Entry
• Text-Based Entry
39
Test Equipment
• Analog Oscilloscope
• Digital Oscilloscope
• Logic Analyzer
• Logic Probe, Pulser, and Current Probe
• DC Power Supply
• Function Generator
• Digital Multimeter
40
Oscilloscope
41
Figure 1--34 A typical dual-channel digital oscilloscope. Numbers below screen are arbitrary and are shown for illustration only.
42
Figure 1--36 A typical dual-channel analog oscilloscope.
43
Figure 1--37 Typical logic analyzers
Logic Analyzer
44Figure 1--38 Illustration of how a logic probe is used to detect various voltage conditions at a given point in a circuit.
Logic Probe
45
Figure 1--40 Typical test instruments
46Figure 1--41 Simplified basic block diagram for a tablet-counting and bottling control system.
Digital System Application