Digital Fundamentals

Digital Fundamentals

CHAPTER 1 Digital Concepts

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1.1 Digital and Analog Quantities

• Analog quantities have continuous values • Digital quantities have discrete sets of values

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Digital and Analog Quantities (cont…)

Analog quantities have continuous values

Digital quantities have discrete sets of values

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Digital and Analog Quantities (cont…)

Types of electronic devices or instruments: • Analog • Digital • Combination analog and digital

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1.2 Binary Digits, Logic Levels, and Digital Waveforms

• The conventional numbering system uses ten digits: 0,1,2,3,4,5,6,7,8, and 9. • The binary numbering system uses just two digits: 0 and 1.

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Binary Digits, Logic Levels, and Digital Waveforms (cont…)

• The two binary digits are designated 0 and 1 • They can also be called LOW and HIGH, where LOW = 0 and HIGH = 1

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Binary Digits, Logic Levels, and Digital Waveforms (cont….)

Binary values are also represented by voltage levels

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Binary Digits, Logic Levels, and Digital Waveforms (cont….)

Major parts of a digital pulse • Base line • Amplitude • Rise time (tr) • Pulse width (tw) • Fall time (tf)

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Binary Digits, Logic Levels, and Digital Waveforms (cont….)

• • •

tw = pulse width T = period of the waveform f = frequency of the waveform 1 f= T

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Binary Digits, Logic Levels, and Digital Waveforms (cont….)

The duty cycle of a binary waveform is defined as:  tw  Duty cycle =  100%  T 

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1.3 Basic Logic Operations There are only three basic logic operations:

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Basic Logic Operations (cont….)

The NOT operation

• When the input is LOW, the output is HIGH • When the input is HIGH, the output is LOW The output logic level is always opposite the input logic level. Slide 12

Basic Logic Operations (cont….)

• The AND operation – When any input is LOW, the output is LOW – When both inputs are HIGH, the output is HIGH

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Basic Logic Operations (cont….)

• The OR operation – When any input is HIGH, the output is HIGH – When both inputs are LOW, the output is LOW

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Overview of Basic Logic Functions (cont….)

• • • • • • • •

Comparison function Code conversion function Arithmetic functions Encoding function Decoding function Data selection function Data storage function Counting function Slide 15

Overview of Basic Logic Functions (cont….)

Comparison function • Compares two binary values and determines whether or not they are equal Code conversion function • Converts, or translates, information from one code format to another Slide 16

Overview of Basic Logic Functions (cont….)

Arithmetic functions • Perform the basic arithmetic operations on two binary values: – Addition – Subtraction of two values – Multiplication – Division

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Overview of Basic Logic Functions (cont….)

Encoding function • Converts non-binary information into a binary code Decoding function • Converts binary-coded information into a non-binary form

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Overview of Basic Logic Functions (cont….)

Data selection function • Multiplexer (mux) – Switches digital data from any number of input sources to a single output line

• Demultiplexer (demux) – switches digital data from a single input to any number of output lines

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Overview of Basic Logic Functions (cont….)

Data storage function • Retains binary data for a period of time – Flip-flops (bistable multvibrators) – Registers – Semiconductor memories – Magnetic-media memories – Optical-media memories

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Overview of Basic Logic Functions (cont….)

Counting function • Generates sequences of digital pulse that represent numbers

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1.4 Fixed-Function Integrated Circuits

IC package styles • Dual in-line package (DIP) • Small-outline IC (SOIC) • Flat pack (FP) • Plastic-leaded chip carrier (PLCC) • Leadless-ceramic chip carrier (LCCC)

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Fixed-Function Integrated Circuits (cont….)

• Dual in-line package (DIP)

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Fixed-Function Integrated Circuits (cont….)

• Small-outline IC (SOIC)

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Fixed-Function Integrated Circuits (cont….)

• Flat pack (FP)

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Fixed-Function Integrated Circuits (cont….)

• Plastic-leaded chip carrier (PLCC)

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Fixed-Function Integrated Circuits (cont….)

• Leadless-ceramic chip carrier (LCCC)

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1.5 Test and Measurement Instruments

• • • •

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

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