digital fundamentals - electronics research...

Digital Fundamentals

Introductory Digital

Concepts

Objectives

•Explain the basic differences between digital and analog quantities

•Show how voltage levels are used to represent digital quantities

•Describe various parameters of a pulse waveform such as rise time, fall time, pulse width, frequency, period, and duty cycle

•Explain the basic logic operations of NOT, AND, and OR

•Describe the logic functions of the comparator, adder, code converter, encoder, decoder, multiplexer, demultiplexer, counter, and register

•Identify fixed-function digital integrated circuits according to their

Introductory Digital Concepts 2

complexity and the type of circuit packaging

•Identify pin numbers on integrated circuit packages

•Describe the PLD, discuss the various types, and state how PLDs are programmed

•Recognize digital instruments and understand how they are used in troubleshooting digital circuits and systems

•Show how a complete digital system is formed from the basic functions in a practical application

Analog signalThe choices you have to make when converting an analog signal to adigital representation

•samling interval•max/min amplitude level•number of bits (dynamics)etc.

HEY WAKE UP!

Digital and analog quantities


Digital samplingHEY WAKE UP! what kind of extra

choices you can think of?

An example of a system of analog electronics

I wonder if these are purely analog anymore?

The volume can be controlled with buttons

digitally?


An example of a system of mixed analog and digital electronics


Source for the comparison was S.J. Cahill: Digital and Microprocessor Engineering. 2nd ed.

Binary presentation with zeros and ones

Ideal pulses

Real pulses


Real pulses

The levels are specified differentlyfor the families (e.g. TTL, CMOS)

Waveform characteristics

fT

Tf

1,

1 == %100

=T

tcycleDuty W


A Digital waveform carries binary information


Timing diagrams


Data transfer Serial

Parallel

AN EXAMPLEInterfacing TM-6710,


Interfacing TM-6710,digital camera

Intro to basic logic operations

NOT


AND

OR


Comparison function


Aritmetic functions


-Substraction

* Multiplication

/ Division

Code conversion - encoder


Code conversion - decoder


Data selection – multiplexing/demultiplexing


Storage SERIAL


PARALLEL

Counting


Fixed-function ICs (integrated circuits)


IC Packages


Pin numbering


Classification of complexity for ICs


Programmable logic devices (PLDs)

SPLD

CPLD

advantages:•takes less space•design procedure is fasterwithout rewiring and replacingcomponents

Three major types:•SPLD (simple ...)•CPLD (complex ...)•FPGA (field-programmable gate arrays)


FPGAs can have upto 1000 pins!

Programming•schematic or•text-based approach

HDL – hardware description languageABEL, CUPL, VHDL, Verilog

Intro to test instruments

Digital oscilloscope with 4 channels, color display, diskette drive for storage etc.

Can you say what is the biggestdifference when using an analogor a digital oscilloscope?


Portable oscilloscope for measuring analog/digitalsignal in e.g. industrial environment

Typical dual-channel oscilloscope

Digital


Analog

Hands on tip


Logic analyzer


Logic probe

When measuring beware not to induceunwanted shortcircuits which can destroythe D.U.T. (device under test).


Basic instruments Do not forget the importance of a good power supply: digital devices requireusually supply with ±5% regulation!


Digital application

What is the purpose of the comparator (comp)?

What happens whenthe output A = B goeshigh?


Can you say whatare the contents ofthe registers at anygiven time?

digital fundamentals - electronics research...

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