Introductory Digital Concepts Chapter 1 Introductory Digital Concepts

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

Figure 1--1 Graph of an analog quantity (temperature versus time).

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.

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.

Figure 1--3 A basic audio public address system. Analog Electronic System Figure 1--3 A basic audio public address system.

Figure 1--4 Basic principle of a CD player. Only one channel is shown. System Using Digital and Analog Methods Figure 1--4 Basic principle of a CD player. Only one channel is shown.

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.

Figure 1--5 Logic level ranges of voltage for a digital circuit. Logic Levels Voltages used to represent 1 and 0. Figure 1--5 Logic level ranges of voltage for a digital circuit.

Figure 1--7 Nonideal pulse characteristics. Digital Waveforms Figure 1--6 Ideal pulses. Figure 1--7 Nonideal pulse characteristics.

Frequency and Period Frequency (f) # cycles per sec or Hertz (Hz) Period (T) in seconds. f=1/T, T = 1/f

Figure 1--8 Examples of digital waveforms. Periodic and Nonperiodic Figure 1--8 Examples of digital waveforms.

Pulse Width and Duty Cycle Figure 1--9 Duty Cycle = (tw/T)100 %

Digital Waveform Carries Binary Information Figure 1--10 Example of a clock waveform synchronized with a waveform representation of a sequence of bits.

Figure 1--11 Example of a timing diagram.

Data Transfer Figure 1--12 Illustration of serial and parallel transfer of binary data. Only the data lines are shown.

Figure 1--15 The basic logic operations and symbols.

Figure 1--16 The NOT operation.

Figure 1--17 The AND operation.

Figure 1--18 The OR operation.

Basic Logic Functions Comparison Function Arithmetic Functions Code conversion function Encoding function Decoding function Data selection function Data storage function Counting function

Figure 1--19 The comparison function.

Figure 1--20 The addition function. Arithmetic Function Figure 1--20 The addition function.

Code Conversion Function: Encoder Figure 1--21 An encoder used to encode a calculator keystroke into a binary code for storage or for calculation.

Code Conversion Function: Decoder Figure 1--22 A decoder used to convert a special binary code into a 7-segment decimal readout.

Data Selection Function Figure 1--23 Illustration of a basic multiplexing/demultiplexing application.

Data Storage Function 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 Figure 1--25 Example of the operation of a 4-bit parallel shift register.

Figure 1--26 Illustration of basic counter operation. Counting Function Figure 1--26 Illustration of basic counter operation.

Fixed-Function Integrated Circuits 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.

IC Packages 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.

Figure 1--29 Examples of SMT package configurations.

Pin Numbering Figure 1--30 Pin numbering for two standard types of IC packages. Top views are shown.

Integrated Circuit Technologies TTL ECL CMOS NMOS SSI and MSI use TTL or CMOS VLSI and ULSI use CMOS or NMOS

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)

Types of SPLD PAL (Programmable Array Logic) GAL (Generic Array Logic) PLA (Programmable Logic Array) PROM (Programmable Read-only Memory)

Figure 1--32 Typical CPLD packages. Types of CPLD CPLDs are made using 2 to 64 SPLDs Figure 1--32 Typical CPLD packages.

PLD programming Schematic Entry Text-Based Entry

Test Equipment Analog Oscilloscope Digital Oscilloscope Logic Analyzer Logic Probe, Pulser, and Current Probe DC Power Supply Function Generator Digital Multimeter

Oscilloscope

Figure 1--34 A typical dual-channel digital oscilloscope Figure 1--34 A typical dual-channel digital oscilloscope. Numbers below screen are arbitrary and are shown for illustration only.

Figure 1--36 A typical dual-channel analog oscilloscope.

Figure 1--37 Typical logic analyzers

Logic Probe Figure 1--38 Illustration of how a logic probe is used to detect various voltage conditions at a given point in a circuit.

Figure 1--40 Typical test instruments

Digital System Application Figure 1--41 Simplified basic block diagram for a tablet-counting and bottling control system.