dvw (digital wave viewer) user manual

Copyright 1990-2015 Piero Belforte Giancarlo Guaschino

DWV

Digital Wave Viewer

USER'S MANUAL


This document contains proprietary information of Piero Belforte and Giancarlo

Guaschino.

All rights are reserved.

The contents of this document may not be copied or reproduced in any form

without the express prior permission of Piero Belforte and Giancarlo Guaschino.

Piero Belforte and Giancarlo Guaschino shall not be liable for errors contained

herein and the information contained in this document is subject to change

without notice.

UNIX is a trademark of AT&T Bell Laboratories

X-Window is a trademark of Massachusetts Institute of Technology

Table of Contents DWV

Table of Contents

Table of Contents ........................................................................................................i

Chapter 1: Introduction to DWV.........................................................1

1.1 General Features................................................................................2

1.2 DWV Environment............................................................................4

1.3 Starting and Stopping DWV..............................................................7

1.4.1 Standard Graphic Format......................................................8

1.4.2 Input Format for X/Y Plots...................................................9

1.4.3 Expression Files..................................................................10

1.4.4 PWL Input Format..............................................................12

Chapter 2: User Interface....................................................................15

2.1 Basic Graphic Presentation..............................................................16

2.2 Commands Input.............................................................................17

2.3 Graphic Mode Selections................................................................23

2.4 Display Lists....................................................................................28

2.5 System Windows.............................................................................29

2.6 Commands Conventions..................................................................31

Chapter 3: Input-Output Functions...................................................33

3.1 LOAD..............................................................................................34

3.2 UNLOAD........................................................................................35

3.3 SAVE...............................................................................................35

3.4 LIST.................................................................................................35

3.5 VIEWFILE......................................................................................37

3.6 EDITFILE........................................................................................37

3.7 SHOWGFILE..................................................................................37

3.8 SETGFILE.......................................................................................38

Chapter 4: Waveform Display Commands........................................39

4.1 MPLOTALL....................................................................................42

4.2 PLOTALL.......................................................................................43

4.3 SCANPLOT....................................................................................43

4.4 MPLOT............................................................................................44

4.5 PLOT...............................................................................................45

4.6 EYE-DIAG Secondary Menu..........................................................47

i


4.6.1 EYED..................................................................................47

4.6.2 MEYED..............................................................................49

4.6.3 MEYEDALL.......................................................................51

4.7 LIMIT-EYE Secondary Menu.........................................................52

4.7.1 LEYE..................................................................................52

4.7.2 LEYEPLOT........................................................................55

4.7.3 LEYEMPLOT.....................................................................55

4.7.4 LEYEINFO.........................................................................55

4.7.5 LEYESAVE........................................................................57

4.7.6 LSEQSAVE........................................................................57

4.7.7 LEYEFREE.........................................................................59

4.7.8 LEYELOAD.......................................................................60

4.8 PLOTTYPE.....................................................................................61

4.9 ZOOM.............................................................................................62

4.10 PANNING.....................................................................................64

4.11 PANSTEP......................................................................................66

4.12 DISPLIST......................................................................................66

4.13 CANCEL.......................................................................................68

4.14 CLEAR..........................................................................................69

4.15 STARTIME...................................................................................69

Chapter 5: Defining Axes and Grid....................................................71

5.1 DEFAXES.......................................................................................73

5.2 XAXIS.............................................................................................74

5.3 XLIMIT...........................................................................................75

5.4 XSCALE..........................................................................................76

5.5 YLIMIT, AUTO-YLIMIT...............................................................76

5.6 GRID Secondary Menu...................................................................77

5.6.1 GRID OFF...........................................................................77

5.6.2 AUTOSPACING................................................................78

5.6.3 XOFFSET...........................................................................81

5.6.4 YOFFSET...........................................................................81

5.6.5 XDELTA.............................................................................82

5.6.6 YDELTA.............................................................................82

Chapter 6: Making Hardcopies..........................................................83

6.1 PLOTSAVE.....................................................................................85

6.2 PLOTEXEC.....................................................................................86

ii


6.3 HARDCOPY...................................................................................87

6.4 PRINTERSETUP............................................................................88

6.5 KILLCOPY.....................................................................................89

Chapter 7: Utility Commands.............................................................91

7.1 LSDIR, LSDIR -T...........................................................................92

7.2 EVAL..............................................................................................93

7.3 FFT..................................................................................................95

7.4 TITLE..............................................................................................96

7.5 LABEL............................................................................................96

7.6 BACKGROUND.............................................................................97

7.7 MASKGEN.....................................................................................98

7.8 MASKEDIT....................................................................................98

Chapter 8: Model Capture System (MCS) Utilities..........................99

8.1 PWLONWAVE.............................................................................101

8.2 PWLONGRID...............................................................................101

8.3 PWLEDIT......................................................................................104

8.4 PWLIST.........................................................................................105

8.5 PWLSAVE....................................................................................105

8.6 PWLFREE.....................................................................................106

8.7 PWLOAD......................................................................................106

Chapter 9: Help and End of the Work Session...............................109

9.1 HELP.............................................................................................110

9.2 EXIT..............................................................................................110

9.3 INFO..............................................................................................110

Chapter 10: Syntax of the Mathematical Expressions....................111

INDEX.................................................................................................115

iii


iv

Chapter 1

I n t roduct ion to DWV

1.1 General Features

1.2 DWV Environment

1.3 Starting and Stopping DWV

1.4 Input File Format

1.4.1 Standard Graphic Format

1.4.2 Input Format for X/Y Plots

1.4.3 Expression Files

1.4.4 PWL Input Format

Chapter 1 1

1.1 General Features

The graphic processor DWV has been designed to fully exploit the power of the

companion simulator DWS in a highly interactive environment.

In order to assure maximum opening toward further developments and portability

on today and future workstations, it has been developed utilizing the multivendor

standard release X11 of the X-Window System. This feature allows DWV users

to operate as well in a network-based simulation environment.

DWV has been developed simplifying as far as possible its use, through a user-

friendly interface giving the user at the same time powerful tools for signal

analysis and processing. Both keyboard and mouse operations are available

while multi-level pop-up menus are mouse selectable to send commands.

DWV can basically process a list of graphic files (each containing one or more

waveforms) obtained also from different sources including other simulator's

outputs or results of experimental measurements. This is a very important feature

because it allows the user to evaluate the effect of parameter changes during an

optimization loop or to compare actual measurements with simulations.

Waveform processing can be accomplished by means of the available set of

mathematical functions and/or by means of the same DWS simulator which can

operate a true digital signal processing on stored waveforms. The vectors, called

"expressions", created by means of mathematical functions are treated like the

other vectors of samples and the user can save them on file for further

utilizations.

Several graphic display formats are selectable. Multiple waveform displays can

be obtained in both overlapped and non-overlapped mode. In the latter case, each

waveform is automatically associated to a horizontal strip of the graphic window.

Multiple non-overlapped displays are very useful for relative waveform

Chapter 1 2

comparison as required for timing analysis, when the number of displayed vectors

is large.

Another display mode is obtainable by associating the horizontal x-axis to one of

the stored variables. In this way it is very easy to monitor the evolution of a

network transient in a v,i (voltage vs current) plane. This functioning mode is

particularly useful in the analysis of circuits showing oscillating or even chaotic

behaviors or to see the evolution of working points of circuits driving reactive

loads (e.g. digital buffers driving a backplane bus) in order to monitor if the

operation point stays in the safe area.

Like its companion simulator DWS, DWV is strongly oriented to advanced

digital electronics needs. For this reason it includes several features for signal

integrity evaluation, such as the eye-pattern display. By defining a bit time, one

or more waveforms can be overlapped on a time window corresponding to the bit

time. Eye-patterns are particularly useful in pointing out important features of the

digital signal such as eye opening, timing jitters and residual noise margins.

DWV can also calculate and display the worst-case eye-pattern related to

a single waveform edge coming from measurement or simulation. The bit-

sequence causing the maximum eye closure at a given frequency is determined

and can be stored for further use on the measure or simulation environment.

The MCS (Model Capture System) of DWV gives the user the capability of

interactive piecewise-linear fitting of a stored waveform. This feature is

extremely useful to model dynamic behaviors coming from actual measurements

or previous simulations because it is linked to the simulator by means of the file

containing the breakpoints in a DWS-compatible input syntax.

Chapter 1 3

1.2 DWV Environment

Error: Reference source not

found

DWV operation requires some environment files located in the following

directories:

com,

cursors,

doc,

startup.

The com directory contains the UNIX shells printcolor and printbw used by

DWV to make hardcopies.Error: Reference source not found

The cursors directory contains the files defining the bitmaps of the shapes of

mouse cursor.Error: Reference source not found

The doc directory contains the DWV.help file which allows the user to display

the DWV user manual.Error: Reference source not found

The following files, containing several parameters which the user can set, are

located in the startup directory:Error: Reference source not found

DWVcolormap

DWVcomlas

DWVcomplot

DWVformat

DWVstartup

The DWVcolormap file contains hexadecimal numbers corresponding to the

colors utilized by DWV.Error: Reference source not foundError: Reference

source not found

Chapter 1 4

The DWVcomlas and DWVcomplot files contain the commands which have to

be executed to make a hardcopy with a laser printer and a plotter respectively (see

the plotexec command).Error: Reference source not foundError: Reference

source not foundError: Reference source not foundError: Reference source not

found

For example, the plotter command could be:

cat $1 > /dev/plotter

where /dev/plotter is the driver of the plotter and $1 is the name of the file

carrying the saved plot.

The DWVformat file contains two integer numbers in plotter units that specify

the maximum plotting ranges for x and y axes respectively. The two numbers

given as default (10900, 7650) refer to A4 format. For A3 plots, these values

must be modified in 16000 and 10900.Error: Reference source not foundError:

Reference source not found

The DWVstartup file contains other parameters which the user can set, as shown

in the next page for both SUN and HP platforms. These parameters are:

- the number of fonts used by DWV;

- the font identifiers (all the available fonts are described in the directory

/usr/openwin/lib/fonts on SUN or /usr/lib/X11/fonts on HP);

- the prompt in the command window;

- the shape of the cursor in the command window;

- the identifier of the font for the command window;

- the number of spaces assigned to tab;

- beep volume (from 0 to 100);

- the number of commands stored in history vector.

Chapter 1 5

############################################################## ## DWV# Digital Wave Viewer# # *** SETUP FILE *** ## font number # 8 # # font 0 for panning prompts "<" ">" # fonts 1 2 3 4 5 for internal window text # These fonts must be written in order of decreasing character dimension # font 6 for display labels # font 7 for menu # 12x248x16 7x13 6x13 6x10 5x89x158x13bold # # terminal prompt #*># # terminal cursor #_ # # font identifier for terminal#1## space number assigned to tab#8## beep volume#100## number of commands stored in history vector#20

Chapter 1 6

1.3 Starting and Stopping DWV

Before starting, make sure to have a user-account set up to run DWV . To start

DWV, use the following steps:

1) Log on to the workstation and (if necessary) start up the X-Window system.

2) Create a window where operating system commands can be entered.

3) Move to the required project directory.

4) Enter the command:

DWV [-d hostname:displ_num.screen_num] [-m maskname [-s type_edit]]

where:

-d is an option which allows the user to address DWV on a display different from the default screen.

hostname is the machine name (workstation or X-terminal) where the user wishes to display DWV.

displ_num specifies the display server number of this machine (usually displ_num is equal to 0).

screen_num specifies the screen to be used by the server (usually screen_num is equal to 0).

-m -s are options used in PRESTO environment to create or edit signal masks (see PRESTO USER'S MANUAL).

The DWV basic graphic screen appears.

The following steps explain how to end a DWV work session:

1) Move the mouse cursor to exit on the pop-up menu and press the right mouse

button. A confirmation message appears.

2) Type Y to exit.

Chapter 1 7

1.4 Input File Format

1.4.1 Standard Graphic Format

These graphic files contain waveforms versus time (common waveforms are

voltages, currents, etc) in .g format. These files are usually created by the

simulator DWS or by DWV itself. In addition, the user can handle waveforms

captured from measurement instrumentation.

The files, coming from simulators or instruments, must have the following

structure:

FILE_NAME

NUMBER_OF_WAVEFORMS

NUMBER_OF_SAMPLES_PER_WAVEFORM

SAMPLING_TIMESTEP

<START_TIME>

WAVEFORM_NAME #1

LIST_OF_SAMPLES

WAVEFORM_NAME #N

LIST_OF_SAMPLES

<COMMENTS>

where:

FILE_NAME is the name of the file containing the waveform(s) to be displayed.

See Command Conventions for more details.

NUMBER_OF_WAVEFORMS is the number of waveforms included in the file

specified by FILE_NAME. NUMBER_OF_WAVEFORMS must be a nonzero

unsigned integer.

NUMBER_OF_SAMPLES is the number of samples of each waveform

included in the file specified by FILE_NAME. NUMBER_OF_SAMPLES must

be at least 2 and is the same for each waveform belonging to this file. Files with

Chapter 1 8

different values of NUMBER_OF_SAMPLES can be loaded simultaneously in

DWV.

SAMPLING_TIMESTEP is the time between two contiguous samples of the

same waveform expressed in seconds. Only fixed time steps are allowed.

SAMPLING_TIMESTEP applies to all waveforms included in a file. Files with

different SAMPLING_TIMESTEP can be loaded simultaneously in DWV.

Usually the time is assumed as independent variable and all waveforms are given

versus time.

START_TIME is the (optional) starting time of the sequence of samples

expressed in seconds and applies to each waveform included in the same file.

Files with different START_TIME can be loaded simultaneously in DWV. If not

specified START_TIME is assumed to be 0.

WAVEFORM_NAME is the name of the waveform. See Command

Conventions for more details.

LIST_OF_SAMPLES is the list of samples of the waveform specified by

WAVEFORM_NAME. Each sample is given in exponential notation. More than

one sample is allowed on the same line. The number of samples must match the

number specified in NUMBER_OF_SAMPLES, otherwise an error message is

issued when the file is loaded.

COMMENTS are allowed in DWV file format after the last list of samples. Each

comment line must have an asterisk "*" as first character of the line. DWV will

ignore the contents of comment lines.

1.4.2 Input Format for X/Y Plots

This input format allows the user to display waveforms versus another waveform

that is represented by the first vector in the file.

Chapter 1 9

The file syntax is equal to the standard graphic format (see 1.4.1) with the

exception of the parameter SAMPLING_TIMESTEP that is set to 0.0.

1.4.3 Expression Files

The "expression" files created by DWV through a dedicated command (see save

command) are identified by a character "$" as extension of the name specified by

the user during the saving procedure. These files contain samples of one

waveform as result of a mathematical operation previously performed on stored

waveforms.

The format of an "expression" file is the following:

EXPRESSION

NUMBER_OF_WAVEFORMS

NUMBER_OF_SAMPLES

SAMPLING_TIMESTEP

<START_TIME>

EXPRESSION_CODE

LIST_OF_SAMPLES

<COMMENTS>

Error: Reference source not found

where:

EXPRESSION is the complete expression name containing the mathematical

operations applied to the original samples.

NUMBER_OF_WAVEFORMS is the number of waveforms included in the file

(in this case it is 1).

NUMBER_OF_SAMPLES is the number of samples of the waveform included

in the file. NUMBER_OF_SAMPLES must be at least 2.

Chapter 1 10

SAMPLING_TIMESTEP is the time between two contiguous samples of the

waveform expressed in seconds. Only fixed time steps are allowed. Expression

files with different SAMPLING_TIMESTEP can be loaded simultaneously in

DWV.

START_TIME is the (optional) starting time of the sequence of samples

expressed in seconds. If not specified it is assumed to be 0.

EXPRESSION_CODE is a mnemonic code used to identify the waveform (see

Command Conventions).

LIST_OF_SAMPLES is the list of samples of the expression. Each sample is

given in exponential notation. More than one sample is allowed on the same line.

The number of samples must match the number specified in

NUMBER_OF_SAMPLES, otherwise an error message is issued when the file is

loaded.

COMMENTS are allowed in expression file format after the list of samples.

Each comment line must have an asterisk "*" as first character of the line. DWV

will ignore the contents of comment lines.

The previous elements must respect the same order and must be separated by

BLANK, TAB or NEWLINE characters. Fig.1.4.3.1 shows an example of a

standard graphic file and Fig.1.4.3.2 shows an example of "expression" file.

The DWV file format is DWS-compatible and is used in particular to describe the

behavior of independent sources, the dynamic transfer function of controlled

elements and scattering-parameter elements.

Chapter 1 11

Fig.1.4.3.1 - Example of standard graphic file.

Fig.1.4.3.2 - Example of "expression" file

1.4.4 PWL Input Format

The PWL input format is created using pwlsave command and contains the (x y)

coordinates of the breakpoints extracted using the commands pwlonwave or

pwlongrid.

The format of a PWL file is the following:

COMMENT

COMMENT

<COMMENT>

BREAKPOINT_LIST

Chapter 1 12

where:

COMMENT is a line in which the character "*" is in first column.

The first line COMMENT contains the following information: graphic file name

and PWL-fitted waveform name, number of breakpoints, type of approximation

(0 -> PWLONWAVE or 1-> PWLONGRID), abscissa of the first breakpoint.

The second line COMMENT contains the maximum value and the minimum

value of the graphic window in which the PWL-fitted waveform was displayed.

Additional comment lines can follow, if the PWL-fitted waveform has the

independent variable different from time.

BREAKPOINT_LIST contains the coordinates of each breakpoint enclosed

between the " PWL( " keyword and ")". Each breakpoint abscissa is given with

reference to the abscissa of the first breakpoint.

Fig. 1.4.4.1 shows an example of PWL file.

* Y_vector= demo.g:V(2) points:8 extr_type:1 init_time:2.00ns 08/06/94 10:43

* lm:0.0000e+00 rm:1.8000e-07 bm:1.0000e-03 tm:5.1000e-03

PWL (0.00ns 1.20mV 2.00ns 3.20mV 4.00ns 4.60mV 6.00ns 5.00mV

+ 12.00ns 5.00mV 32.00ns 5.00mV 86.00ns 5.00mV 140.00ns 5.00mV)

Fig.1.4.4.1 Example of PWL input format.

The DWV PWL file format is DWS-compatible and is used in particular to

describe the behavior of independent sources, the static and dynamic transfer

functions of controlled elements and scattering-parameter elements.

Chapter 1 13

.

Chapter 1 14

User Interface DWV

Chapter 2

User In te r face

2.1 Basic Graphic Presentation

2.2 Commands Input

2.3 Graphic Mode Selections

2.4 Display Lists

2.5 System Windows

2.6 Commands Conventions

Chapter 2 15

User Interface DWV

2.1 Basic Graphic Presentation

The graphic screen of Fig.2.1.1 appears upon invoked the command DWV from a

window where operating system commands can be entered.

Fig.2.1.1 - DWV basic graphic screen.

It is possible to identify three areas on it:

- Graphic window. This area is used to display waveforms and the system

windows. The DWV pop-up menu is active in this area. Commands are

selectable by positioning the graphic cursor of the mouse in the pop-up menu

and pressing once the left mouse button.Error: Reference source not found

- Command window. On the bottom left of the graphic window there is the user

command window that allows the input of DWV commands through the

keyboard. Moreover, the system uses this frame to display messages.

Chapter 2 16

User Interface DWV


- On the bottom right of the graphic window there are some slot-windows used to

monitor data about the waveform limits (LM: left margin, RM: right margin,

BM: bottom margin, TM: top margin) and the marker position (only in eval or

pwlextract mode). In this area there is also a status flag that informs about the

current status and two arrows for panning operations.Error: Reference source

not found

2.2 Commands Input

User commands are issued either using the keyboard or choosing a selection

directly from the pop-up menu with the mouse. The system windows are

automatically activated by DWV to help the selection of the parameters, if

needed.

- Keyboard

The command interpreter of DWV has been developed using the lexical

analyzer generator LEX and the syntactic analyzer generator YACC (both

UNIX utilities). The interpreter is always in active status so, anyway the

command is introduced, it is analyzed and, if correct, it is executed (the

interpreter is not case sensitive).

DWV can accept mathematical expressions created with the four elementary

algebraical operations or other mathematical operators, like sin, cos, tan, ln, log,

sqr, sqrt, exp, abs and avg (average of a vector of samples). These functions

support vectors or real numbers as parameters (a real number is always declared

as a double precision constant in DWV). If the result of the expression is still a

vector, it is stored in memory using the default internal data structure and it is

available for any other operation through an identification label, as well as any

other waveform loaded from files. The label is composed by a character meaning

the type of waveform (voltage, current, etc.) and an unsigned integer

(automatically incremented by the interface). The character "$" completes the

code.

For example, the command:

Chapter 2 17

User Interface DWV

plot I(TINT,10) * V(10)

creates a new vector of samples Pk$ which is the kth new vector generated

during the current work session.

The mathematical functions are accepted only within one of the commands: plot,

mplot, eyed and meyed.

A history function is available and stores the last command in a vector. The

default length of the vector is 20 commands, but the user can set this parameter

by modifying its value in the DWVstartup file. It is possible to recall commands

from the history record with the UP and DOWN keys on keyboard. The

command is printed on the user command window and it is possible to execute it

pressing the RETURN key on keyboard or the right button of the mouse. If the

scanning operation goes ahead until the first command stored, the line in the user

command window is deleted and a beep occurs, signaling the end of the history

record.

- Mouse

The pop-up menu is activated positioning the graphic cursor inside the graphic

window and pressing the left button of the mouse. The first level of the pop-up

menu shows the main selections. Stars on the left and right of the labels mean that

secondary menus are available for further selections.

The selections with secondary menus (a_selections) are: Error: Reference source not found- FILES - DISPLAY - AXES - HARDCOPY - UTILITY - MCS - INFO

The selections without secondary menu (b_selections) are:Error: Reference

source not found

- HELP - EXIT

Chapter 2 18

User Interface DWV

To activate a command from pop-up menu, move the graphic cursor in the related

label frame of the main_menu (the associated label will be highlighted in reverse

mode) and press the left button of the mouse.

For b_selections, the associated command is displayed on the user command

window and, if no other parameters are needed, it is executed.

For a_selections, a new secondary menu is shown. If the secondary menu has

other a_selections, it is necessary to repeat the above procedure until the

command is achieved.

The next three pages summarize the available selection tree.Error: Reference

source not found

Chapter 2 19

User Interface DWV

MENU SELECTIONS

FILES........... LOAD

UNLOAD

SAVE

LIST

VIEWFILE

EDITFILE

SHOWGFILE

SETGFILE

DISPLAY...... MPLOTALL

PLOTALL

SCANPLOT

MPLOT....... MPLOT

MPLOT BYNET

PLOT........... PLOT

PLOT BYNET

EYE-DIAG... EYED

MEYED

MEYEDALL

LIMIT-EYE... LEYE

LEYEPLOT

LEYEMPLOT

LEYEINFO

LEYESAVE

LSEQSAVE

LEYEFREE

LEYELOAD

PLOTTYPE... NORMAL

COMB

SPECTRUM

ZOOM

PANNING

PANSTEP

Chapter 2 20

User Interface DWV

DISPLIST..... DISPLIST

DISPLIST BYNET

CANCEL....... CANCEL

CANCEL BYNET

CLEAR

AXES............ DEFAXES

XAXIS.......... TIME

VECTOR

XLIMIT

XSCALE...... LINEAR

LOG

YAXIS........... AUTO-YLIMIT

YLIMIT

GRID............. ON................ AUTO-SPACING

XOFFSET

YOFFSET

XDELTA

YDELTA

OFF

HARDCOPY..... PLOTSAVE... PLOTTER

LASER

PLOTEXEC... PLOTTER

LASER

COLOR

BLACK/WHITE

FILE

PRINT STP... COLOR

BLACK/WHITE

UTILITY....... LSDIR -T

LSDIR

EVAL

FFT.............. LINEAR

DB

Chapter 2 21

User Interface DWV

TITLE ...................... ON

OFF

LABEL

BACKGROUND..... BLACK

WHITE

MASK ..................... MASKGEN

MASKEDIT............. RISE_UPPER

RISE_LOWER

FALL_UPPER

FALL_LOWER

MCS.............. PWLEXTRACT....... PWLONWAVE

PWLONGRID

PWLEDIT

PWLIST

PWLSAVE

PWLFREE

PWLOAD

HELP

EXIT

INFO

Chapter 2 22

User Interface DWV

2.3 Graphic Mode Selections

DWV has 6 different plotting modes:


- plot mode

- multiplot mode

- eye-diagram mode

- multieye-diagram mode

- leyeplot mode

- leyemplot mode

A detailed description of each of them is presented in this section.

- plot mode.

The plot mode is activated by the commands plot and plotall which display

overlapped the vectors of samples specified as parameters (Fig.2.3.1).

Fig.2.3.1 - Example of plot mode display.

Chapter 2 23

User Interface DWV

The grid is automatically set. However, dedicated commands allow the user to

redefine grid and ranges of the scale.

In plot mode all the functions are enabled: panning, zoom on y-axis and Piece-

Wise-Linear (PWL) fitting of waveforms are only available in plot mode.

This plotting mode is useful for visual comparison between two or more

waveforms and for PWL fitting during the creation of models.

- multiplot mode.

This plotting mode is activated by the commands mplot and mplotall which

display the vectors of samples specified as parameters. Waveforms are displayed

individually, each of them in a horizontal strip of the graphic window. The x-axis

is common for all the waveforms displayed but each trace has a customized y-

axis with a scale which is automatically set in order to contain each waveform in

its horizontal strip (Fig.2.3.2). However, dedicated commands allow the user to

redefine grid and ranges of the scale.

Fig.2.3.2 - Example of multiplot mode display.

The number of waveforms only depends on graphic resolution of the display.

Typically up to 100 waveforms can be displayed with 1024x768 pixel monitors.

Chapter 2 24

User Interface DWV

In multiplot mode the following functions are not available: panning, zoom

on y-axis and PWL fitting of waveforms. This graphic mode is useful to display

several waveforms simultaneously for timing analysis or when two or more

waveforms show very different ranges of values along y-axis.

- eye-diagram mode.

This graphic mode is activated with the command eyed which displays

overlapped the eye-diagrams of the vectors specified as parameters (Fig.2.3.3).

In this mode the functions eval, panning, xaxis, xlimit, zoom, and PWL fitting

are not enabled.

This waveform display mode, originally introduced for analysis of transmission

systems, is very useful to analyze digital signals and point out signal integrity

margins. In fact, it allows the user to check the waveforms about noise margins,

timing, jitters, etc.

Fig.2.3.3 - Example of eye-diagram mode display.

- multieye-diagram mode.

Similarly to the previous section, this graphic mode is activated by the commands

meyed and meyedall which display the eye-diagrams of the vectors specified as

Chapter 2 25

User Interface DWV

parameters each one in a separate horizontal strip of the graphic window. Each

trace has a customized y-axis with a scale automatically set in order to contain

each waveform in its horizontal strip (Fig.2.3.4). However, dedicated commands

allow the user to redefine grid and ranges of the scale.

Functionality and limitation are similar to the eye-diagram mode.

Fig.2.3.4 - Example of multieye-diagram mode display.

- leye-plot mode.

The leye-plot mode is activated by the command leyeplot. All the limit eye-

diagrams specified as parameters are displayed in overlapped mode, as described

in the section dedicated to the plot mode. Fig.2.3.5 shows an example of leye-plot

mode.

A limit eye-diagram shows the internal and external envelopes of the eye-

diagram generated by the worst-case sequence of bits applied to the system. A

worst-case sequence is the sequence determining the maximum closure of the

eye. DWV calculates the limit eye-diagram starting from a single (rising or

falling) signal edge (leye command). The user can also store the worst-case

sequence on disk.

In the leye-plot mode the following functions are disabled: panning, xaxis,

xlimit, zoom and PWL fitting.

Chapter 2 26

User Interface DWV

Fig.2.3.5 - Example of leye-plot mode display.

- leye-mplot mode.

The leye-mplot mode is activated by the commands leye and leyemplot. All the

limit eye-diagrams specified as parameters are displayed individually (Fig.2.3.6)

each one in a horizontal strip of the graphic window. The functions disabled are

the same of the leye-plot mode.

Each waveform is displayed with its own color for identification purposes; the

same color is used to display the waveform name on the upper right corner of the

graphic window in plot, eye-diagram and leye-plot modes.

Chapter 2 27

User Interface DWV

Fig.2.3.6 - Example of leye-mplot mode display

2.4 Display Lists

Each one of the previous shown display modes uses an independent waveform

list. In fact, each of the commands seen before updates its own table of data. The

waveforms specified as parameters remain in the list until unloaded using the

clear or cancel commands. For example, the following commands sequence:

mplot V(10) V(30) plot V(20)mplot P(TINT,10) eyed 0.0 200 I(TINT,10)

displays the waveforms V(10) and V(30) in multiplot mode, then V(20) in plot

mode, then V(10) V(30) P(TINT,10) in multiplot mode again and, at the end, the

eye-diagram of I(TINT,10).

Chapter 2 28

User Interface DWV

2.5 System Windows

DWV has five different system windows:


- list window

- displist window

- pwlist window

- leyeinfo window

- lsdir window

These windows can be directly activated either with specific commands or using

commands selected within the pop-up menu. This last procedure is often used to

facilitate the selection of the command parameters.

The list window shows the graphic files currently loaded into the memory. The

displist window lists the waveforms currently displayed on the screen and the

pwlist window lists the waveforms that have been used for PWL extractions. The

leyeinfo window gives the user information concerning the limit eye-diagrams

generated with the command leye. The lsdir window lists the contents of the

working directory. Fig.2.5.1 shows how the system windows look on the graphic

window.

For more details concerning the information displayed in the system windows,

please refer to the related commands. In the following it is shown how to manage

a system window from a general point of view.

Each window has several fields:


- the data field uses the major amount of the window space and it is used to

display the requested data.

- The closing field is a red square placed on the upper right corner of the window.

Pressing the left button of the mouse on this field causes the closure of the

window.

- The data displayed are organized in pages and the fields pageup and pagedown

control the scroll of the pages.

Once the window is displayed, it is activated by placing the graphic cursor of the

mouse inside its frame. When the cursor is placed within the window, the color of

Chapter 2 29

User Interface DWV

window boundaries and of the graphic cursor will change until the cursor will be

held inside the window.

Fig.2.5.1 - DWV system windows.

In the system windows the information is displayed in pages and it is possible to

scroll the pages by positioning the graphic cursor in the scrolling fields and

pressing the left button of the mouse. The selected field is displayed in reverse

mode when the graphic cursor is within the selected frame.

It is possible to select some fields of the information displayed on the windows,

by pointing at the information needed (the correspondent field will be displayed

in reverse mode) and pressing the left button of the mouse. This procedure copies

the selected information from the system window to the command window and

makes it available to the command interpreter, once the keyboard <ENTER> or

<RETURN> is pressed.

A window is disactivated by moving the mouse out of it. When this happens the

color of the window boundaries becomes that of a disactivated window.

In order to cancel one of the system windows from the screen it is sufficient to

point at the red square placed in the upper right corner and press the left button of

the mouse (the execution of some commands, like plot, mplot, etc., causes the

automatic closure on the related system windows).

Chapter 2 30

User Interface DWV

2.6 Commands Conventions

This section lists some conventions used in the following of the manual.

- id a letter followed by any combination of letters, digits or the special

character ".".

E.g. bus6, a0file

- num unsigned integer number.

E.g. 4

- real real number.

E.g. 10., 10.3, -4.5

- var character coding the waveform type. The following types are

available (DWS syntax):

A incident voltage wave, B reflected voltage wave, I current, G ratio between reflected and incident waves, P instantaneous power, Q incident instantaneous power, R reflected instantaneous power, V voltage, Y port reference admittance, Z port reference impedance.

- wf waveform name with the following DWS syntax:

var([id,]num) or var(num,num)

where id is an element name of the network and num is a node

identifier.

E.g. V(10), I(TINT,30), V(10,20)

- expr expression with the syntax:

var-num-$

E.g. P1$

Chapter 2 31

User Interface DWV

- name name of a generic vector not included in the previous classes wf

and expr. The syntax is:

#-id or #-num-$.

The second case applies to the results of mathematical operations

which cannot be described as var types.

E.g. #2$.

- vector specifies a waveform, an expression or a generic name. In general,

ambiguities during the selection of waveforms can be avoided

through the specification of the file name that contains the

waveform. The character ":" is used to separate the two names (file

and vector).

The syntax is:

wf or expr or name.

E.g. plot.g:V(1), V(1), V2$, #3$

- pathname specifies a path using UNIX-like syntax. Wild-cards are not

allowed.

E.g. /pathname/file.g

- filename string composed by any combination of letters, digits or the

special characters ".", "_" and "$".

- opt command option that specifies a device.

E.g. -l for laser printer, -p for plotter.

Note: the character "-" used in the syntax definition of the parameters expr and

name means that no space has to separate the elements.

Chapter 2 32

Input-Output Functions DWV

Chapter 3

I nput -Output Funct ions

3.1 Load

3.2 Unload

3.3 Save

3.4 List

3.5 Viewfile

3.6 Editfile

3.7 Showgfile

3.8 Setgfile

Chapter 3 33


These commands can be typed directly from keyboard or by selecting them with

the mouse from the FILES secondary menu (Fig.3.1). They allow the user to

load, save and manage graphic files.

For some particular I/O functions, like commands related to limit eye-diagram

calculation or PWL extraction, please refer to the specific sections.

Fig.3.1 - FILES secondary menu.

3.1 LOAD

Syntax:

load pathname1 [pathname2 ... pathnamen] Error: Reference source not found

This command loads the contents of selected graphic file(s) in memory. The file,

specified by pathname, can contain either waveforms coming from simulations or

measurements or an expression. During the loading, the file identifier is appended

in the list of the graphic files (see list command).

DWV can manage several graphic files and expressions at the same time. The last

file loaded becomes the "current" graphic file and all the defaults will refer to

it.Error: Reference source not found DWV recognizes the type of the file during

the loading by analyzing the file format (standard graphic file, X/Y graphic file,

expression file or PWL file). "Expression" files are characterized by the suffix

"$". Maximum file name length is 32 characters.

E.g.:

load test.dat <--- file containing a simulation

Chapter 3 34


load test.dat$ <--- file containing an expression

3.2 UNLOAD

Syntax:

unload [filename]

unload [expr]

unload removes the contents of a graphic file or of an expression from the

memory. The identifiers of all the vectors included in the file are also deleted

from the display list. If the unload command is selected without parameters, the

current graphic file is unloaded.Error: Reference source not found

The unloading of the current graphic file causes the printing of a warning

message and the file in the first position of the list becomes the new current

graphic file.

3.3 SAVE

Syntax:

save vector filename


save creates a file, using the name specified by filename, which contains the

vector of samples specified by vector. The file created is an "expression" file and

the character "$" at the end of the file name is automatically provided.

3.4 LIST

Syntax:

list

Chapter 3 35



This command displays in the system window list (Fig.3.4.1)Error: Reference

source not found some information related to the graphic files loaded in DWV

and to the expressions already calculated within the working session. If the

command is activated when the list window is already present on the graphic

window, its contents are updated with the new information.

For standard graphic files related to simulations or measures, the following

information is displayed:

- name of the file, - number of samples for each waveform,- sampling time step, - waveform names.

For expression files, the window displays:

- name of the file, - number of samples, - sampling time step, - expression code, - complete expression.

For the expressions not already stored in a file, the label "EXPRESSION"

replaces the name of the file. The waveform names and the expression codes are

fields that can be selected with the mouse. For the selection it is sufficient to

point at the field and to press the left button of the mouse. The string displayed in

the field will be automatically printed in the command window. If the selected

field is related to a waveform or expression stored in a file, the name of file is

automatically associated and the character ":" is included as separator.

Chapter 3 36


Fig.3.4.1 - Example of list window.

3.5 VIEWFILE

Syntax:

viewfile filename


viewfile opens a text window and invokes the vi UNIX text editor on the file

specified by filename. The file is open in "read-only" option, in order to avoid

any change in the original file. All vi-UNIX commands are available.

Type ":q" to close the view session.

3.6 EDITFILE

Syntax:

editfile filename


editfile opens a text window and invokes the vi UNIX text editor on the file

specified by filename. All vi-UNIX commands are available.

Type ":wq" to close the edit session by saving the last modifications or ":q" to

quit without saving the last modifications.

3.7 SHOWGFILE

Syntax:

showgfile


showgfile prints the name of the current graphic file on the command window.

Chapter 3 37


3.8 SETGFILE

Syntax:

setgfile filename


This command assigns to the file specified by filename the status of "current

graphic file". Upon selecting this command, all the functions will automatically

refer to this file.

setgfile is useful when many files are loaded in memory and the user wants to

refer to vectors without specifying everytime the file name for each of the

vectors.

For example, if the first file loaded has the name first.g and contains the

waveforms V(1) V(2) V(3) and the second file loaded has the name second.g, the

second.g file is automatically the current graphic file. Instead of the command:

mplot first.g:V(1) first.g:V(2) first.g:V(3)

it is possible to use the following sequence of commands:

setgfile first.g

mplot V(1) V(2) V(3)

Chapter 3 38

Waveform Display Commands DWV

Chapter 4

Waveform D isp lay Commands

4.1 Mplotall

4.2 Plotall

4.3 Scanplot

4.4 Mplot

4.5 Plot

4.6 Eye-diag Secondary Menu

4.6.1 Eyed

4.6.2 Meyed

4.6.3 Meyedall

4.7 Limit-eye Secondary Menu

4.7.1 Leye

4.7.2 Leyeplot

4.7.3 Leyemplot

4.7.4 Leyeinfo

4.7.5 Leyesave

4.7.6 Lseqsave

Chapter 4 39


4.7.7 Leyefree

4.7.8 Leyeload

4.8 Plottype

4.9 Zoom

4.10 Panning

4.11 Panstep

4.12 Displist

4.13 Cancel

4.14 Clear

4.15 Startime

Chapter 4 40


These commands are available either directly from keyboard or through a

selection of the DISPLAY secondary menu. All the commands that are shown in

this section enable the user to display waveforms with several plotting modes

which do not change the value of the waveform samples. Some of the menu

entries contain secondary menus as shown in Fig.4.1.

Fig.4.1 - DISPLAY secondary menu.

Chapter 4 41


4.1 MPLOTALL

Syntax:

mplotall [filename]


mplotall displays all the vectors contained in the current graphic file, each one in

a dedicated horizontal strip of the graphic window (Fig.4.1.1). If the optional

parameter filename is given, mplotall displays all the waveforms included in the

file specified by filename.

If other vectors are already displayed using multiplot mode, the new vectors are

added to them.

Fig.4.1.1 - Example of display obtained with the mplotall command.

Chapter 4 42


4.2 PLOTALL

Syntax:

plotall [filename]


plotall displays all the vectors contained in the current graphic file in overlapped

mode. If the optional parameter filename is given, plotall displays all the

waveforms included in the file specified by filename.

If other vectors are already displayed using plot mode, the new vectors are added

to them.

4.3 SCANPLOT

Syntax:

scanplot [-s startnet | -f pathname] [-t scantime] filename


User Note:

This command can be only used inside PRESTO environment.

scanplot displays all the vectors contained in the file specified by filename, net by

net, in alphabetic order and in overlapped mode.

Additional parameters are:

startnet specifies the first net to be plotted. The previous nets (in alphabetic

order) are skipped.

pathname specifies the name of a file containing the list of nets to be

displayed during the scanplot command execution.

scantime specifies the visualization time (in seconds) for each net. If the -t

option is not specified, the default value is one second.

Chapter 4 43


4.4 MPLOT

Syntax:

mplot [vector1 [vector2 ... [vectork]]]

mplot -n [netname1 [netname2 ... [netnamek]]]

User Note:

The option -n can be only used inside PRESTO environment.

mplot displays the vectors specified as parameters using multiplot mode, like the

mplotall command (Fig.4.4.1). The vectors can be results of simulations,

measurements acquired from instruments, expressions or PWL breakpoints. If

other vectors are already displayed using multiplot mode, the new vectors are

added to them. If no parameter is specified, the command mplot changes from the

current plotting mode to multiplot mode, displaying the screen generated with the

last mplot or mplotall command.

In PRESTO environment, mplot -n (MPLOT BYNET from pop-up menu) can be

used to plot all the vectors belonging to a net.

The parameter netname can be:

- the net name [filename.g:]net written in complete way or

- a string, composed by a part of the net name, followed by the character "*",

for example CLK*. In this case all the nets whose name begins with the string

CLK will be displayed.

Chapter 4 44


Fig.4.4.1 - Example of display obtained with the mplot command.

The mplot command enables the interpreter of mathematical functions. This

means that the parameter specified in the syntax can be an expression containing

numerical constants, vectors and mathematical operators (see Syntax of the

Mathematical Expressions).

E.g.: mplot V(1) abs(V(10) + sqrt(34.5)) - avg(V(20))

The interpreter of mathematical expressions creates new vectors of samples. In

fact, upon the command is inserted, the expressions are calculated and, if the

result is still a vector, it is stored in memory and becomes available for further

operations as well as any other standard vector directly loaded in the program

from file. If the result of the expression is a number, the interpreter works like a

calculator and prints the result on the command window.

Error: Reference source not foundError: Reference source not foundError:


4.5 PLOT

Syntax:

plot [vector1 [vector2 ... [vectork]]]

Chapter 4 45


plot -n [netname1 [netname2 ... [netnamek]]]


User Note:


plot displays the vectors specified as parameter in overlapped mode, using the

full graphic window (Fig.4.5.1). The vectors can be results of simulations,

measurements acquired from instruments, expressions or PWL breakpoints.

In PRESTO environment, plot -n (PLOT BYNET from pop-up menu) can be

used to plot all the vectors belonging to a net in overlapped mode.

The parameter netname can be:

- the net name [filename.g:]net written in complete way or

- a string, composed by a part of the net name, followed by the character "*", for

example CLK*. In this case all the nets whose name begins with the string CLK

will be displayed.

Fig.4.5.1 - Example of display obtained with the plot command.

The waveforms displayed on the screen are plotted with different colors for

identification purposes. The same color is used to write the vector identifier on

the upper right corner of the graphic window.

Chapter 4 46


If other vectors are already displayed in plot mode, the new vectors are added to

them. If no parameter is specified, the command plot changes from the current

plotting mode to the plot mode, displaying the screen generated with the last plot

or plotall statement.

plot enables the interpreter of mathematical expressions as well as shown in the

previous mplot section.

Chapter 4 47


4.6 EYE-DIAG Secondary Menu


This section contains all the commands that allow the user to enter the eye-

diagram or multieye-diagram plotting modes. Upon selecting the EYE-DIAG

command, the following secondary menu is displayed:

All the commands related to these plotting modes are explained in the following.

4.6.1 EYED

Syntax:

eyed beg_time freq [vector1 [vector2 ... [vectorn]]]


eyed displays the eye-diagram of the vectors specified as parameters in

overlapped mode for a specified bit-rateError: Reference source not found

(freqError: Reference source not found) expressed in Mbit/s. The parameter

beg_time Error: Reference source not foundspecifies the time starting from which

the eye-diagram is displayed. All the samples related to times lower than

beg_time are not displayed. The parameter beg_time has to be given in the same

scale assigned to the x-range related to the last mplotall, plotall, mplot or plot

command.

For example, Fig.4.6.1.1 shows the graphic window obtained with the command

sequence:

mplot V(10) V(20) V(30)

Chapter 4 48


eyed 100 50 V(10) V(30)

If no vector is specified, eyed refreshes the screen and displays the vectors

already specified and stored in the eyed list with the new starting time and bit-

rate. The interpreter of mathematical functions is active and all the considerations

done for the mplot command apply also in this context. Plotting waveforms in

eye-diagram mode is very useful for the verification of the behavior of digital

circuits about signal integrity. In fact, by superimposing the single bits (or clock

cycles) the user obtains a clear display of the time jitterError: Reference source

not found and of the noise margin reduction caused by ringing, crosstalk,

bouncing, delay skews, etc.

Fig.4.6.1.1a - Source waveforms for the eyed command.

Chapter 4 49


Fig.4.6.1.1b - Example of display obtained with the eyed command.

4.6.2 MEYED

Syntax:

meyed beg_time freq [vector1 [vector2 ... [vectorn]]]


meyed displays the eye-diagrams of the vectors specified as parameters for a

defined bit-rate (freq) expressed in Mbit/s. Each eye-diagram is plotted in a

dedicated horizontal strip of the graphic window. The parameter beg_time

specifies the time starting from which the eye-diagrams are displayed. All the

samples related to times lower than beg_time are not displayed. The parameter

beg_time has to be given in the same scale assigned to the x-range related to the

last mplotall, plotall, mplot or plot command.

Fig.4.6.2.1a - Source waveforms for the meyed command.

Chapter 4 50


Fig.4.6.2.1b - Example of display obtained with the meyed command.

For example, Fig.4.6.2.1 shows the graphic window obtained with the command

sequence:

mplot V(10) V(20) V(30)

meyed 100 50 V(10) V(30)

If no vectors are specified, meyed refreshes the screen and displays the vectors

already specified and stored in the meyed list with the new starting time

and bit-rate.

The interpreter of mathematical functions is active and all the considerations

done for the mplot command apply also in this context.

Chapter 4 51


4.6.3 MEYEDALL

Syntax:

meyedall beg_time freq


meyedall displays the eye-diagram of all the vectors contained in the current

graphic file for a specified bit-rate (freq) expressed in Mbit/s. Each eye-diagram

is plotted in a dedicated horizontal strip of the graphic window. The parameter

beg_time specifies the time starting from which the eye-diagrams are displayed.

All the samples related to times lower than beg_time are not displayed. The

parameter beg_time has to be given in the same scale assigned to the x-range

related to the last mplotall, plotall, mplot or plot command.

Chapter 4 52


4.7 LIMIT-EYE Secondary Menu

This section contains all the commands that allow the user to enter the limit eye-

diagram facilities and the related plotting modes. Upon selecting the command,

the following secondary menu is displayed:

4.7.1 LEYE

Syntax:

leye [-oc] beg_time [-w fin_time] [-s swing] freq vector


Starting from a waveform related to a single rising or falling edge of a two level

signal (vector) generated by a linear circuit, the command leye evaluates:

- the limit eye-diagramError: Reference source not found of the selected signal, at

the bit-rate specified by the parameter freq, which shows the envelope of the

worst-case eye-diagram due to intersymbol interferenceError: Reference source

not found. The limit eye-diagram is constituted by both an internal shape,

including the inner upper and inner lower boundaries, and an external shape (-o

option), including the outer upper and outer lower boundaries (Fig.4.7.1.1);

Chapter 4 53


- the bit sequences causing the inner envelope of the limit eye-diagram (test

sequences). These sequences can be used as test patterns for worst-case

simulations of the system. These sequences can also be used as worst-case test

patterns during the testing phase of the prototype.

Fig.4.7.1.1a - Source waveform for the leye command.

Chapter 4 54


Fig.4.7.1.1b - Example of display obtained with the leye command.

The options -oc have the following meaning:

-o The outer envelope (upper and lower) of the limit eye-diagram is also

evaluated.

-c The limit eye-diagram is calculated using a clock sequence (010101...).

The parameter beg_time is a real number specifying the sample (on x-axis) of the

rising or falling edge starting from which the limit eye-diagram has to be

evaluated. The optional parameter fin_timeError: Reference source not found is a

real number specifying the time of the last sample for which the limit eye-

diagram is calculated. The final time must be chosen in order to include the

whole edge transient. If it is omitted, DWV assumes the time of the last sample of

the waveform as final time. Both the parameters beg_time and fin_time have to

be given using the same scale of the x-axis assigned by the last plot, plotall,

mplot or mplotall command.

The worst-case sequencesError: Reference source not foundError: Reference

source not found of bits are calculated for each sample of the response used as

reference. If the time window between beg_time and fin_time is very large

compared to the bit time, very long sequences are generated as result. In reality,

some bit contributions to the closure of the eye are indeed negligible and could be

ignored. It is possible to filter the worst-case bit sequences by avoiding the bits

whose contributions to the eye-closure are less than a small fraction of the signal

Chapter 4 55


swing, specified by the parameter swingError: Reference source not found. The

bits so identified are shown in the sequence through the simbol X (don't care).

The parameter freq is a real number specifying the bit-rate (in Mbit/s) for which

the limit eye-diagram is evaluated. If the option -c is specified in the parameter

list, freq is expressed in MHz.

A numerical identifier is assigned to each limit eye-diagram calculated. Further

references to the limit eye-diagram are done through this identifier. The

command leye displays the limit eye-diagram calculated in leyemplot mode.

Chapter 4 56


4.7.2 LEYEPLOT

Syntax:

leyeplot [-all] [num1 [num2 ... [numn]]]


leyeplot displays the previously generated (see leye command) limit eye-diagrams

given as parameters in overlapped mode. If the -all option is specified, the

diagram is displayed with the waveform that has been used for its generation. The

leyeplot mode allows the user to use the eval command.

4.7.3 LEYEMPLOT

Syntax:

leyemplot [-all] [num1 [num2 ... [numn]]]


leyemplot displays the previously generated (see leye command) limit eye-

diagrams passed as parameters in non-overlapped mode, assigning a horizontal

strip of the display area for each diagram. If the -all option is specified, the

diagram is displayed with the waveform that has been used for its generation. The

leyemplot mode allows the user to use the eval command.

4.7.4 LEYEINFO

Syntax:

leyeinfo


This command enables the system window leyeinfo. The information that is

displayed in this window is organized in pages, one for each limit eye-diagram

Chapter 4 57


included in the current limit eye-diagram list (and created through the command

leye). The same information is also available during the selection of the

commands leyeplot and leyemplot using the mouse. If the command eval is

activated when one or more limit eye-diagrams are displayed on the screen, the

limit eye-diagram list is also enabled but the information displayed refers

only to the limit eye-diagrams displayed on the current graphic window.

The information displayed with the command leyeinfo is:

- the name of the file containing the source waveform that has been used for the

generation of the limit eye-diagram,

- the waveform name,

- the identifier assigned to the diagram and the identifiers of the two or four

boundaries forming the diagram (inner upper, inner lower, [outer upper, outer

lower]),

- the number of samples,

- the sampling time step,

- the start and stop time delimiting the interval of the waveform (rise or fall edge)

that has been used for the generation of the limit eye-diagram,

- the bit-rate (or the frequency in case of clock sequence),

- the fraction of the waveform amplitude that has been specified through the

parameter swing.

Chapter 4 58


Fig.4.7.4.1 - Example of leyeinfo window.

It is possible to select with the mouse some of the displayed fields, in particular:

- the identifier of the limit eye-diagram,

- the identifiers of the two (or four) boundaries of the limit eye-diagram (these

identifiers are required by the command eval) (Fig.4.7.4.1).

4.7.5 LEYESAVE

Syntax:

leyesave num [filename]


This command saves on a file all the waveforms (two or four) defining the limit

eye-diagram identified by num. The file name is specified by the optional

parameter filename. If omitted, the default name leyedataError: Reference source

not found is used.

DWV stores the samples on a data file in the same format of a standard graphic

file. The names of the waveforms are made up by an initial character (the type of

the master waveform used for the generation of the graph) followed by a

progressive number between round brackets.

At the end of the file there are some comment lines with a character "*" in the

first column containing the information reported in the leyeinfo system window.

4.7.6 LSEQSAVE

Syntax:

lseqsave num filename

Chapter 4 59


lseqsave num1 [num2 ... [numk]] filename


This command stores on a file the bit sequence causing the inner envelope of the

limit eye-diagram identified by num. If more identifiers are specified, DWV will

find the worst-case bit sequence for each limit eye-diagram and the global worst-

case bit sequence will be created taking into account the contribution of each

worst-case bit sequence.

The name of the output file containing the bit sequence is specified through the

parameter filename.

The worst-case bit sequences are usable as test-patterns in order to check an

actual prototype under test or to simulate the system in worst-case conditions

(Fig.4.7.6.1).

DWS can directly use the stored worst-case sequences in order to define the

behavior of independent sources (see DWS USER'S MANUAL).

The bits are expressed as "0" or "1", if their contribution to the closure of the eye

is significant. This condition is verified if the bit contribution to the closure of the

eye is greater or equal to the fraction of the signal amplitude specified by the

parameter swing in the leye command; if this contribution is negligible, the

relative bit is shown with the symbol X (don't care).

The command leye, with the exception of the case in which the -c option has been

used, calculates for each time point of the eye-diagram the bit sequence which

causes the maximum closure of the eye for that point. Upon the command

lseqsave is activated, DWV compacts the sequences that are equal, so that the file

contains only unique sequences. Moreover the number of occurrences of each

sequence is indicated.

In the output file the comment lines begins with a character "*".

User Note:

The command lseqsave with more than one identifier (num1 num2

...) specified is very useful to find the global worst-case bit

sequence for an interconnection with more than one receiver.

Infact, the worst-case bit sequences at each receiver are combined

in a single bit sequence.

Chapter 4 60


Chapter 4 61


* number of occurrences: 97* 110* number of occurrences: 57* 100* number of occurrences: 186* 010* number of occurrences: 78* 101* number of occurrences: 106* 111* number of occurrences: 4* 011

* worst-case sequence000110000100000010000101000111000011111001111011111101111010111000111100* bit number: 72* sequence length: 7.20us* date: 08/06/94 14:40* source file: test.g* waveform: V(10) identifier: 1* source file: test.g* waveform: V(20) identifier: 2* source file: test.g* waveform: V(40) identifier: 3* bit_rate: 10.00Mbit/s

Fig.4.7.6.1 - Example of file containing worst-case bit sequence.

4.7.7 LEYEFREE

Syntax:

leyefree num 1 [num2 ... [numn]]


leyefree erases the eye-diagram specified by num from the limit eye-diagram list.

Upon selecting the command, the limit eye-diagram that has been deleted cannot

be displayed again before a new version is created with the leye command.

Chapter 4 62


4.7.8 LEYELOAD

Syntax:

leyeload pathname


leyeload loads a file, specified by pathname, containing the samples of a limit

eye-diagram, previously saved with the command leyesave.

All the information loaded is inserted in the limit eye-diagram list.

Upon loading the file, the diagram can be displayed with the commands leyeplot

and leyemplot.

Chapter 4 63


4.8 PLOTTYPE

Syntax:

plottype normal

plottype comb

plottype spectrum

plottype selects the plotting mode of the samples displayed on the graphic

window. The selection is active until the next plottype command is executed.

Using "normal" mode the samples are displayed as points on the screen and line

segments connecting each point with the next (Fig.4.8.1a), while the samples are

displayed as vertical segments starting from the x-axis (y=0) in "comb" mode

(Fig.4.8.1b). "Spectrum" mode is similar to "comb" mode with the exception that

the samples are displayed as vertical segments starting from the bottom of the

graphic window.

User Note:

As default, DWV uses the "normal" mode to display time domain

waveforms and "spectrum" mode to display Fast Fourier

Transform (FFT) results.

Chapter 4 64


Fig.4.8.1a - Example of "normal" plotting mode.

Fig.4.8.1b - Example of "comb" plotting mode.

4.9 ZOOM

Syntax:

zoom Error: Reference source not found

zoom sets the grid ranges (along both x and y directions in plot mode and only

x-range in multiplot mode) of the current graphic window.

Upon selecting the command, four markers are displayed at the limits of the x

and y axes. These markers can be captured with the mouse and moved to another

position, so that a new display area can be defined. Pushing the right button of the

mouse, the screen area delimited by the new positions of the markers is displayed

to full screen.

Chapter 4 65


Fig.4.9.1a - Example of graphic window before the zoom command.

Fig.4.9.1b - Example of graphic window after the zoom command.

Chapter 4 66


A marker can be moved by positioning the graphic cursor close the marker and

by pressing the left button of the mouse. In this way the marker is captured and

will follow the mouse movement until the button is pressed. The information

displayed in the bottom right windows (X, Y current marker position) is updated

during the movement. Upon releasing the button, the marker stops in the current

position. The right button is used to complete the procedure, after the new limits

of the window are defined: the area delimited by the marker is displayed and the

control returns to the command interpreter (Fig.4.9.1a,b).

The new limits hold active until the next command zoom, defaxes (restore the

default ranges), xlimit or ylimit is issued.

Note: there are no limits on the number of times the command zoom is used on

the same waveform.

4.10 PANNING

Syntax:

panning


panning enables the panning function if the waveforms are already displayed in

plot mode, otherwise, the command is ignored. Upon selecting the command, two

squares are displayed on the bottom right of the graphic window with the simbols

"<" and ">". These squares are used to shift the waveforms displayed on the

graphic window to the right (<) or to the left (>). Upon positioning the graphic

cursor on one of the two squares, each time the left button of the mouse is

pressed, the current graph is shifted to the right or to the left (Fig.4.10.1a,b). The

amount of the shift is 1/25 of the x-range as default. This default value can be

modified with the command panstep (see command panstep).Error: Reference

source not found

To exit the panning mode, it is necessary to press the right button of the mouse

with the graphic cursor positioned inside one of the two panning squares. Upon

pressed the button, the two squares disappear and the control returns to the

command interpreter. panning is particularly useful after a zoom command in

Chapter 4 67


order to shift the displayed area of the zoomed waveform.Error: Reference source

not found

Fig.4.10.1a - Example of graphic window before the panning command.

Chapter 4 68


Fig.4.10.1b - Example of graphic window after a panning step.

4.11 PANSTEP

Syntax:

panstep [real]


panstep defines the panning step used for the panning function. The parameter

real must be positive and is defined as a fraction of the visible x-range. If

omitted, its default value (1/25 of the visible range) is restored.

4.12 DISPLIST

Syntax:

displist

displist -n


User Note:


displist enables the displist system window and lists on it the identifiers of the

vectors displayed on the graphic window (Fig.4.12.1). If the command is

activated when the displist window is already displayed on the screen, its

contents are updated.

Chapter 4 69


The option -n, inside the PRESTO environment, allows the user to list the

names of the nets instead of the vector identifiers.

Fig.4.12.1 - Example of displist window.

The waveform names (or the net names), sorted file by file, and the expression

labels are user selectable fields. If the graphic cursor is positioned within the

information frame, the selected field is displayed in reverse mode; pressing the

left button of the mouse causes the transfer of the selected field in the command

window. The file name is automatically added to the selection to avoid

ambiguities. The colors of the vector identifiers listed in the displist window are

exactly the same of the related vectors displayed on the graphic window. In case

of expression, its complete mathematical expression is also reported. For leyeplot

and leyemplot modes, the command displist gives the same information of the

command leyeinfo.

Chapter 4 70


4.13 CANCEL

Syntax:

cancel num 1 [num2 ...[numn]]

cancel vector1 [vector2 ...[vectork]]

cancel -n netname1 [netname2 ...[netnamej]]

User Note:


cancel allows the deletion of vectors displayed on the graphic window. It acts

only on the current plotting mode. The fields passed as parameters are the names

of the vectors that have to be erased or their identifiers.Error: Reference source

not foundError: Reference source not found

Upon selecting the command by menu, the system window displist (for plot,

multiplot, eye-diagram and multieye-diagram modes) or leyeinfo (for leyeplot

and leyemplot modes) is displayed, enabling the selection of the vectors to erase.

The command cancel needs at least one parameter, for example:

cancel 1 5 7

cancel V(10) P(TINT,20) filename.g:V(30)

In order to avoid ambiguities, it is suggested to complete the waveform name

with its file name. If the file name is omitted, the interpreter chooses the current

graphic file as default. The current graphic file is the last loaded or the one set

Chapter 4 71


using the command setgfile (see setgfile command). If the selection of the

parameter is performed using the mouse and the displist window, the file name is

automatically added.

The option -n, inside the PRESTO environment, allows the user to cancel all the

vectors belonging to one or more nets just typing the name of the nets instead of

the single vector identifiers.

4.14 CLEAR

Syntax:

clear


This command clears both the display list of the current plotting mode and the

graphic window. clear is only active for the current plotting mode and doesn't

affect the display list of the other plotting modes. If some waveforms have been

displayed in other plotting modes, it is possible to recall them giving the related

plotting command plot, mplot, eyed, meyed, leyeplot or leyemplot without

waveforms names.

For example, the sequence:

plot I(XXX,15)

mplot P(YYY,10)

clear

plot

clears the multiplot mode, whilst the plot command displays I(XXX,15) again.

Chapter 4 72


4.15 STARTIME

Syntax:

startime real vector


The command startime creates an expression containing the selected waveform

vector and assigns the specified value real, expressed in seconds, to the starting

time of this waveform. This command, available only in plot or multiplot mode,

allows the user to shift a waveform in time and compare the waveform with

others.

Chapter 4 73

Chapter 5Error: Reference source not foundError: Reference source not found

Def in ing Axes and Gr id

5.1 Defaxes

5.2 Xaxis

5.3 Xlimit

5.4 Xscale

5.5 Ylimit, Auto-Ylimit

5.6 Grid Secondary Menu

5.6.1 Grid Off

5.6.2 Autospacing

5.6.3 Xoffset

5.6.4 Yoffset

5.6.5 Xdelta

5.6.6 Ydelta

Defining Axes and Grid DWV

This section describes all the commands available to modify the grid step and the

ranges of the two variables along the x and y axes. Upon selecting the command

from the main menu, a secondary menu is activated. By choosing some of the

options displayed in Fig.5.1 other secondary menus of options are activated. All

these commands are explained in details in the following of this chapter.

Fig.5.1 - AXES secondary menu.

Chapter 5 75


5.1 DEFAXES

Syntax:

defaxes


defaxes restores the default plotting ranges for both the graphic window axes: the

default range is defined for x-axis by the number of the waveform samples

multiplied by the timestep specified in the graphic file; if the horizontal variable

has been modified (see xaxis) also the variable time is restored. If two or more

waveforms having different x-rangesError: Reference source not found are

displayed, defaxes will use as default the x-range that is the union of the two

single x-ranges. For y-axis, two situations are possible:

- in plot mode, eye-diagram mode or leyeplot mode: the unit of measure of the

axis is defined by the first vector to plot and the range is evaluated in order to

visualize all the waveforms of the current display list;

- in multiplot mode, multieye-diagram mode or leyemplot mode: if the y-range

has been previously modified (see yaxix), the default y-range for each

waveform is restored (Fig.5.1.1).

Fig.5.1.1 - Example of display after a defaxes command in multiplot mode (the two waveforms have different x-ranges).

Chapter 5 76


5.2 XAXIS

Syntax:

xaxis t

xaxis vector


xaxis allows the user to change the variable assigned to the x-axis.

Upon selecting the command by menu, a secondary menu is displayed (Fig.5.2.1)

listing the related options.

Fig.5.2.1 - XAXIS secondary menu.

The first two labels (time and vector) are options for the command xaxis, whilst

the label xlimit defines a new x-range and will be explained in details later. The

label xscale defines the type of scale along the x-axis.

The command xaxis t assigns the variable time to the x-axis and sets the default

value of the x-range (based on the time windows of the displayed waveforms).

The command xaxis vector assigns the variable vector instead of time to

the x-axis.

Fig.5.2.2 shows an example related to the start-up transient of an oscillator. The

voltage is assigned to the y-axis and the current to the x-axis.

Note: xaxis is only available in plot or multiplot mode.

Chapter 5 77


Fig.5.2.2 - Example of x-y plot: oscillator's start-up trajectory.

5.3 XLIMIT

Syntax:

xlimit lowerxlimit upperxlimit


xlimit defines the new range of the variable along the x-axis. The parameters

lowerxlimit and upperxlimit are two real numbers, respectively the new lower and

upper limits of the range. These range limits are expressed in the same unit and

scale factor already assigned to the x-axis.

xlimit is only available for plot or multiplot mode.

Chapter 5 78


To restore the default values of the axes range it is necessary to use the command

defaxes that restores the variable time on the x-axis too. xlimit acts in similar way

of the zoom command but allows better precision in defining the range limits.

Chapter 5 79


5.4 XSCALE

Syntax:

xscale linear

xscale log


xscale defines the type of the grid along the x-axis:

- linear specifies a uniform grid spacing;

- log specifies a logarithmic grid spacing.

The logarithmic scale is only available if the variable assigned to the x-axis is

different from time.

.

5.5 YLIMIT, AUTO-YLIMIT

Syntax:

ylimit [lowerylimit upperylimit]

Error: Reference source not foundError: Reference source not found

ylimit defines a new y-range of the waveform(s) currently displayed on the

graphic window. If the parameters are omitted (auto-ylimit option), the y-range is

automatically set. The automatic range limits are set to the absolute maximum

and minimum values of the samples of all displayed waveforms in overlapped

modes or of the single waveforms in non-overlapped modes.

The parameters lowerylimit and upperylimit are two real numbers, respectively

the lower and upper limits of the displayed y-range. These range limits are

expressed using the same unit and scale factor already assigned to the y-axis. For

multiplot mode, multieye-diagram mode and leyemplot mode, the new specified

range applies to all the waveforms displayed on the graphic window and the

values must be expressed in Volt, Ampere, Watt, etc. depending on the meaning

of the waveforms.

Chapter 5 80


5.6 GRID Secondary Menu

This section describes the commands enabling the user to modify the grid

currently displayed on the graphic window and includes all the options shown in

the secondary menu of Fig.5.6.1.Error: Reference source not found

Fig.5.6.1 - GRID secondary menu.

5.6.1 GRID OFF

Syntax:

grid off


grid off clears the reference grid displayed on the graphic window.

Upon selecting this command, the waveforms are displayed without any

reference x-y grid. The command is available for all the plotting modes, but, once

activated, it is only active for the current plotting mode and does not affect the

other plotting modes. The command autospacing restores the default x-y grid

configuration.

Chapter 5 81


5.6.2 AUTOSPACING

Syntax:

autospacing


autospacing restores the default configuration of the reference x-y grid shown

during the display operations. The default values of the grid are evaluated

through the following rules:

- x-axis: the vertical lines of the grid span the displayed x-range with a repetition

step of 1/10 of the full x-range;

- y-axis: for plot mode, eye-diagram mode and leyeplot mode the horizontal lines

span the displayed y-range with a repetition step of 1/10 of the full

y-range (Fig.5.6.2.1); for the other plot modes two horizontal lines for

each of the waveforms are only displayed. These two lines are related to

the minimum and the maximum limits of each plotted waveform

(Fig.5.6.2.2).

The autospacing command can be used after grid-related commands such as

xoffset, yoffset, xdelta, ydelta and grid off in order to restore the default x-y grid.

The autospacing command applies to the current plotting mode. For example, the

following sequence:

plot filename.g:V(10)

ydelta 0.5

mplotall

autospacing

plot

displays initially the waveform V(10) in plot mode and the second command

modifies the default grid. Then the command mplotall changes plotting mode and

displays all the waveforms of the file filename.g. Then autospacing restores only

the multiplot mode grid, whilst the next plot command displays the previous

screen in the plot mode with its modified grid.

Chapter 5 82


Fig.5.6.2.1a - Example of plot mode display after x-y grid settings.

Fig.5.6.2.1b - Example of plot mode display after the autospacing command.

Chapter 5 83


Fig.5.6.2.2a - Example of multiplot mode display after x-y grid settings.

Fig.5.6.2.2b - Example of multiplot mode display after the autospacing command.

Chapter 5 84


5.6.3 XOFFSET

Syntax:

xoffset real


xoffset sets a point which a vertical line of the grid will pass through. The

parameter real specifies the point position on the x-axis expressed using the same

unit currently assigned to the x-axis and taking the scale factor (milli, micro,

nano, pico, femto, kilo, mega, tera) into account, as well as the command xdelta

does. The parameter real must be specified between the maximum and the

minimum values of the visible x-range. If the command xoffset is activated

in plot or eye-diagram mode, it will be also active for its related multiplot

or multieye-diagram mode. Leyeplot mode and leyemplot mode are independent.

The default configuration (grid starting from the left limit of the visible range) is

restorable by means of the command autospacing.

5.6.4 YOFFSET

Syntax:

yoffset real


yoffset sets a point which a horizontal line of the grid will pass through. The

parameter real identifies the point position on the y-axis and must be expressed

using the unit currently assigned to the y-axis and taking the scale factor (milli,

micro, nano, pico, femto, kilo, mega, tera) into account, if the waveforms are

plotted in overlapped mode (plot, eye-diagram or leyeplot mode), or using an

absolute value in the other plotting modes, as well as the command ydelta does.

The command yoffset used in multiple plot modes is very useful to compare

waveforms with respect to a common threshold. The setting of yoffset is

independent for each plotting mode.

Chapter 5 85


5.6.5 XDELTA

Syntax:

xdelta real

xdelta modifies the repetition stepError: Reference source not found between two

contiguous vertical lines of the x-y grid for the current plotting mode. The

parameter real uses the same unit assigned to the x-axis taking the scale factor

(milli, micro, nano, pico, femto, kilo, mega, tera) into account, as well as the

command xoffset does. The parameter real must be a non-zero positive real

number. If the command xdelta is activated in plot or eye-diagram mode, it will

be also active for its related multiplot or multieye-diagram mode. Leyeplot mode

and leyemplot mode are independent. The default setting of xdelta (1/10 of the

visible range) is restorable by means of the command autospacing.

5.6.6 YDELTA

Syntax:

ydelta real

ydelta Error: Reference source not foundmodifies the repetition step between two

contiguous horizontal lines of the x-y grid for the current plotting mode. The

parameter real is expressed using the same unit currently assigned to the y-axis

and taking the scale factor (milli, micro, nano, pico, femto, kilo, mega, tera) into

account, if the waveforms are plotted in overlapped mode (plot, eye-diagram or

leyeplot mode), otherwise, it must be expressed as absolute value, as well as the

command yoffset does.

For plot, eye-diagram and leyeplot modes the default value of ydelta is 1/10 of

the displayed y-range. For the other plotting modes (multiple plot modes), the

step of the horizontal lines is the same of the displayed y-range. In this situation,

if the ydelta command is used, DWV plots horizontal lines starting from the

Chapter 5 86


minimum to the maximum values for each y-range displayed on the screen using

real as repetition step.

It is possible to define different values of ydelta for each plotting mode. For

example, in order to restore the default ydelta value in plot mode, it is necessary

to use the command autospacing when the graphic window is set in plot mode.

Chapter 6

Mak ing Hardcop ies

Error: Reference source not

found

6.1 Plotsave

6.2 Plotexec

6.3 Hardcopy

6.4 Printer Setup

6.5 Killcopy

Chapter 5 87

Making Hardcopies DWV

This section describes a set of commands useful to store the contents of the

graphic window in memory (in a format compatible with a printer or a plotter)

and to print them. Upon selecting the command HARDCOPY, the following

secondary menu appears.

Chapter 6 88


6.1 PLOTSAVE

Syntax:

plotsave opt filename


plotsave stores on a file all the information displayed on the current graphic

window. Before using this command it is suggested to arrange the plotting mode

(plot, multiplot, eye-diagram, multieye-diagram, leyeplot or leyemplot mode)

with a suitable x-y grid (see commands xoffset, yoffset, xdelta, ydelta, grid off,

xlimit and ylimit); it is also possible to add a title and labels (see title and label

commands). The option opt defines the type of the device that will be used to

print, in particular -l for laser printer and -p for plotter. The parameter filename

defines the name of the file, belonging to the current directory, that will carry all

the information related to the saved display. The information displayed on the

graphic window is saved in the file using HPGL instructions.

For this command, DWV uses the Error: Reference source not foundDWVformat

fileError: Reference source not found (located in the startup directory) which

contains two integer numbers inError: Reference source not found plotter units

that specify the maximum plotting ranges respectively for x and y axes. The

default DWVformat file contains a couple of numbers for Error: Reference source

not foundA4 format (10900, 7650). For A3 plots, these values must be modified

in 16000 and 10900. The user can include any intermediate values respectively

for abscissa and ordinate: the saved plot will be automatically scaled.

Chapter 6 89


6.2 PLOTEXEC

Syntax:

plotexec opt filename


plotexec makes hardcopies of the display previously saved on a file with the

commands plotsave or pwledit. The option opt defines the type of printing device,

in particular -l applies for laser printer and -p for plotter. The parameter filename

specifies the name of the file carrying the saved plot (located in the current

directory). This command operates with plotters or laser printers that utilize the

communication language HPGL.Error: Reference source not foundError:


DWV creates an independent process that sends the appropriate instructions to

the selected device. Upon selecting this command, the process becomes active

and the control returns to the user. It is preferable to avoid multiple use of this

command until the plotting device is busy.

The command that has to be executed is in a file of the startup directory. The file

has the default name DWVcomplot for the plotter and DWVcomlas for the laser

printer. For example, the plotter command could be:Error: Reference source not

found

cat $1 > /dev/plotter

where /dev/plotter is the driver of the plotter and $1 is the name of the file

carrying the saved plot; while the laser printer command could be:

lp $1

The hardcopy will also indicate the current date and time, the name of the source

graphic file(s) carrying the waveforms and, if specified, a title.

When the plotter is used, DWV allows the plotting in single or multiple colors. In

any case, it is suggested to use a light color for the grid and dark colors for the

waveforms. Before activating the command, the selected device must be

connected and switched on with paper and pens (plotter) already loaded. If the

Chapter 6 90


device is off, DWV displays an error message. If a second plotexec command,

using the UNIX command "cat", is issued when the previous printing process is

still active, both the printing processes become active simultaneously and wrong

operations may occur. In this situation, the user can use the command killcopy

that returns the identifier of the process created by DWV for printing. Then, the

user can kill the process with the UNIX command "kill -9 PID" from terminal

Error: Reference source not found(PID is the identifier returned by the command

killcopy).

Note: even if the DWV working session is terminated during the execution of a

hardcopy, the plotting process will continue until the end.

6.3 HARDCOPY

Syntax:

hardcopy -col

hardcopy -bw

hardcopy -f filename


hardcopy creates a dump file of the graphic window. Three different options are

available:

-col : this selection creates a temporary file in the

<working_directory>/hardcopy directory that will be processed by

the shell printcolor and then sent to the printer. The shell

printcolor is present in $HOME/.DWVenv (or $HOME/.prestoenv

if used in PRESTO environment) and can be modified by the user

(for example to specify the device or the print queue) as specified

in 6.4.

For HP workstations, the command is completely automatic and

prints a color hardcopy of the graphic window only.

For SUN workstations, the execution requires to point to the

graphic window and to click the left button of the mouse. A color

hardcopy of the entire DWV window will be printed.

Chapter 6 91


-bw this selection creates a temporary file in the

<working_directory>/hardcopy directory that will be processed by

the shell printbw and then sent to the printer. The shell printbw is

present in $HOME/.DWVenv (or $HOME/.prestoenv if used in

PRESTO environment) and can be modified by the user (for

example to specify the device or the print queue) as specified in

6.4.


prints a black/white hardcopy of the graphic window only.


graphic window and to click the left button of the mouse. A

black/white hardcopy of the entire DWV window will be printed.

-f filename this selection creates a file in the current directory specified by

filename containing a dump of the graphic window in xwd format.


creates a dump of the graphic window only.


graphic window and to click the left button of the mouse. A dump

of the entire DWV window will be created.

User Note:

If the directory $HOME/.DWVenv does not exist, it is

automatically created by DWV the first time the command

hardcopy (-col or -bw) is invoked. The two user-definible

command shells printcolor and printbw are then copied in the

directory $HOME/.DWVenv from the directory

<installation_directory>/DWV/<version>/com that contains the

default version.

6.4 PRINTERSETUP

Syntax:

printersetup -col

Chapter 6 92


printersetup -bw


printersetup allows the user to edit the UNIX shells utilized to print hardcopies.

Two different options are available:

-col this selection allows the user to edit the file

$HOME/.DWVenv/printcolor (or $HOME/.prestoenv/printcolor if

used in PRESTO environment) and modify the printing statements

(for example to specify the device or the print queue) for color

printers.

-bw this selection allows the user to edit the file

$HOME/.DWVenv/printbw (or $HOME/.prestoenv/printbw if used

in PRESTO environment) and modify the printing statements (for

example to specify the device or the print queue) for black/white

printers.

After the command is issued, the related print shell can be edited. You can

modify the print statement, taking into account that the input file of the shell is in

xwd format.

6.5 KILLCOPY

Syntax:

killcopy


This command returns the identifier of the process (PID) activated with the

command plotexec. The PID can be used with the command "kill -9 PID" typed

in a UNIX window in order to kill the hardcopy process.

Chapter 6 93


Chapter 6 94

Utility Commands DWV

Chapter 7

Ut i l i t y Commands

7.1 Lsdir, Lsdir -t

7.2 Eval

7.3 FFT

7.4 Title

7.5 Label

7.6 Background

7.7 Maskgen

7.8 Maskedit

Chapter 7 95


7.1 LSDIR, LSDIR -T

Syntax:

lsdir [-t] [pathname]


lsdir displays a system window that lists the contents of the directory specified by

the parameter pathname as shown in Fig.7.1.1. If the parameter is missing, the

contents of the current directory are listed (the current directory is the one from

which DWV has been activated).

Pathname can be expressed starting from the root or relatively to the current

directory. The final character "/" for pathname is not mandatory.

E.g.: lsdir /users/design/simulation

lsdir /users/design/simulation/

The fields displayed in the lsdir system window show file and subdirectory

names sorted by column and in alphabetical order (like the UNIX command "ls").

Fig.7.1.1 - Example of lsdir window.

Chapter 7 96


The names are displayed in different color coding the type:


white ---> subdirectory,

yellow ---> general file (the name doesn't terminate with ".g" or "$"),

green ---> graphic file (the name ends with ".g"),

blue ---> expression file (the name ends with "$").

The option -t sorts the names by date and time of their creation or last

modification (similar to the UNIX command "ls -t"). The lsdir window enables

the user to select the fields displayed in it, like the system windows list and

displist. If the graphic cursor is positioned inside the lsdir window, the cursor

shape is replaced with a red arrow. By pointing at internal fields with the graphic

cursor, they are displayed in reverse mode and, if the left button of the mouse is

pressed, the selected name is transferred to the command window.

This data structure is organized in pages. It is possible to scroll the pages by

pointing at the labels PAGE DOWN or PAGE UP and pressing the left button of

the mouse. The red square on the upper right corner is used to close the lsdir

window. The command lsdir is particularly useful for filename selection during

load operations.

7.2 EVAL

Syntax:

eval [vector]

eval [leyeidentifier.curveidentifier]


eval allows the user to perform measurements on the displayed waveforms. Upon

this function is activated in plot or multiplot mode, two markersError: Reference

source not found (left and right) appear on the waveform specified by the

parameter vector (Fig.7.2.1). If leyeplot or leyemplot mode is activated, the

markers appear only on the selected curve delimiting the limit eye-diagram

Chapter 7 97


specified by the parameter leyeidentifier.curveidentifier. Leyeidentifier is the

identifier of the limit eye-diagram to analyze; curveidentifier identifies which

of the two (or four) lines the user wants to evaluate (curveidentifier can assume

one of these four values: il, iu, ol or ou; see leye command).

Fig.7.2.1 - Example of marker information obtained with the eval command.

The information displayed for any position of the markers depends on the

optional parameter, in particular:

1) if the optional argument of eval is specified, the two markers will trace the

selected waveform and the DWV information windows will display:

- abscissa of both markers,

- distance between the two markers along x direction,

- distance between the two markers along y direction,

- ordinate of both markers;

2) if the optional argument is not specified:

- abscissa of both markers,

- distance between the two markers along x direction.

Chapter 7 98


Upon activating the eval command, the graphic cursor assumes the shape "EV"

and two markers appears at the left and right ends of the x-range.

A marker can be moved with the following procedure:

- point at the marker using the mouse,

- press the left button of the mouse: the marker is then captured and will follow

the mouse movement,

- point at the new position and release the button.

The position information is updated in real time during the mouse movement.

Upon releasing the button, the marker stops and the shape "EV" of the graphic

cursor is restored. The right button is used to exit the eval function, coming back

to the command interpreter.

Note: All the user actions (press a button, move the mouse, release the button) are

scheduled as "events" and they are first stored in memory and then analyzed by

the software. Please avoid making these actions too fast, so that all the events

may be correctly processed, otherwise the system can lose someone of them.

7.3 FFT

Syntax:

fft [-d] [-f] beg_time fin_time num vector



fft executes the Fast Fourier Transform of a time-domain vector on a specified

time window. The parameters are:-d sets the Y axis in decibel (dB = 20Log10<vector>).

-f enables a correction filter for the last sample included in the FFT

time window.

beg_time is the starting time of the FFT time window.

fin_time is the ending time of the FFT time window.

Chapter 7 99


num is the number of samples of the FFT. num must be an integer

number between 8 and 4096.

vector is the vector name.

User Note:

The FFT algorithm can be applied on periodic signals only. As a

consequence, in order to work correctly it is necessary to select a

time window that contains an entire number of periods of the

signal to be transformed.

7.4 TITLE

Syntax:

title "string"

title off


title prints or deletes a title positioned on the bottom of the graphic window. The

parameter string must be specified in inverted commas. Any combination of

characters is allowed, with the exception of the inverted commas, for a maximum

length of 80 characters.

The string specified as title will be also printed on plotter or printer hardcopies.

7.5 LABEL

Syntax:

label "string"


Chapter 7 100


label writes an alphanumeric label on the graphic window. The parameter string

must be specified in inverted commas. Upon the command is executed, the

graphic cursor assumes the shape of an arrow positioned in the upper left corner

of the graphic window. The position of the label is selected moving the mouse.

Pressing the left button of the mouse causes the label to be printed on the screen.

This command is useful to add comments on the waveforms displayed on the

screen.Error: Reference source not found

The activation of any other command that causes the modification of the graphic

window (plot, mplot, defaxes, grid, etc.) causes the deletion of all the labels

displayed on the screen. For this reason, the following sequence is recommended:

1) display the waveforms,

2) optionally select suitable ranges of the variables for both x and y axes by

means of the xlimit and ylimit commands,

3) select a suitable grid with the commands xscale, xdelta, xoffset, ydelta, yoffset,

4) add the title,

5) add the labels,

6) use hardcopy commands.

7.6 BACKGROUND

Syntax:

background white

background black


background changes the color of the DWV window. Possible colors are black or

white. Default color is black. Black background is preferred to look waveforms

on the screen, while white background is preferred to make hardcopies.

Chapter 7 101


7.7 MASKGEN

Syntax:

maskgen [-s] maskname

User Note:

This command is available in PRESTO environment only.

maskgen allows the user to define masks useful to check signal integrity (see

PRESTO USER'S MANUAL). The directory, in which the user runs DWV, has

to contain two files describing the rising edge and the falling edge of the

reference signal of the mask in .g format. The file names have to be

r_maskname.g (to describe the rising edge) and f_maskname.g (to describe the

falling edge). DWV allows the PWL description of the upper section and the

lower section of the mask for each edge. The operating procedure is similar to

pwlongrid command. DWV creates four pwl files, respectively named

r_u_maskname.pwl (rise-upper), r_l_maskname.pwl (rise_lower),

f_u_maskname.pwl (fall_upper) and f_l_maskname.pwl (fall_lower).

If the -s option is specified, it is supposed that the fall masks are symmetrical to

the rise masks, so that only two PWL descriptions (related to rising edge) have to

be created.

Chapter 7 102


7.8 MASKEDIT

Syntax:

maskedit id maskname

User Note:

This command is available in PRESTO environment only.

maskedit allows the user to modify the masks created with the maskgen

command. The operating procedure is similar to pwledit command. The user has

to specify the mask shape to be modified by means of the identifier id:

-ru upper section of rising edge of the mask

-rl lower section of rising edge of the mask

-fu upper section of falling edge of the mask

-fl lower section of falling edge of the mask

Chapter 7 103

Model Capture System (MCS) Utilities DWV

Chapter 8

Mode l Capture Sys tem (MCS)

Ut i l i t i es

8.1. Pwlonwave

8.2. Pwlongrid

8.3. Pwledit

8.4. Pwlist

8.5. Pwlsave

8.6. Pwlfree

8.7. Pwload

Chapter 8 105


This section describes the utilities offered by DWV to model simulated or

measured behaviors. In fact, the following commands allow the user to extract

piecewise linear fitting of the waveforms displayed on the graphic window. The

data extracted can be modified or saved on a file with a syntax suitable to the

DWS simulator. Upon selecting the command MCS from the main menu, a

PWLEXTRACT secondary menu is displayed, as shown in Fig.8.1.

Fig.8.1 - PWLEXTRACT secondary menu.

Chapter 8 106


8.1 PWLONWAVE

Syntax:

pwlonwave vector

pwlonwaveError: Reference source not found allows the user to select samples

from the waveform specified by vector currently displayed in plot mode on the

graphic window. Upon selecting the command, the mouse coordinates identified

by the "X:" and "Y:" labels will be displayed in two of the four slot-windows.

The remaining ones display the abscissa of the first selected point (X1) and the

distance (Dx) between the first selected point and the current position of the

marker. The default graphic pointer is replaced with a white cross (marker) and

then positioned on the first sample of the waveform identified by vector. The

marker is forced to move only on the waveform and the user can extract from 3 to

30 samples. The selection is done by positioning the marker on the selected point

and by pressing the left button of the mouse. A hairline will connect the marker

with the last selected sample. The procedure is repeated during the selection of

the other samples. If the independent variable is the time, the marker can only

move on the right of the last selected sample. Upon the fitting is completed,

pressing the right button of the mouse causes the termination of the pwlonwave

command and the control returns to the command interpreter. The selected points

and the other helpful information are stored in the PWL list that carries all the

PWL extractions. It is possible to display and modify an already done PWL

extraction (see pwledit command), or save it on a file (see pwlsave command), or

delete it from the PWL list (see pwlfree command).

8.2 PWLONGRID

Syntax:

pwlongrid [x_step [y_step]] vector

pwlongrid allows the user to extract a piecewise linear fitting of the waveform

vector currently displayed in plot mode on the graphic window. The procedure is

like the pwlonwave command with the exception that the marker movements are

Chapter 8 107


enabled in all the positions of the graphic window instead of being forced to be

on the specified waveform (Fig.8.2.1).

Fig.8.2.1a - PWL extraction: select the point within the graphic window and press the left button of the mouse.

Chapter 8 108


Fig.8.2.1b - PWL extraction: move the graphic cursor to the new position.

Fig.8.2.1c - PWL extraction: press the left button of the mouse to capture the selected point.

The optional parameters x_step and y_step, which are expressed in the same unit

currently assigned to the x-axis and y-axis taking the scale factor into account,

create a grid on the graphic window. During the PWL approximation, the chosen

point will be automatically snapped to the nearest grid node.

The minimum allowed movement step is 2 pixels for both x and y directions. The

default graphic pointer is replaced by a white cross (marker) positioned on the

bottom left corner of the graphic window. The procedure to extract the PWL

fitting is the same of the pwlonwave command. To exit press the right button of

the mouse.

The selected points and the other helpful information are stored in the PWL list

that carries all the PWL extractions. It is possible to display and modify an

already done PWL extraction (see pwledit command), or save it on a file (see

pwlsave command), or delete it from the PWL list (see pwlfree command).

Chapter 8 109


8.3 PWLEDIT

Syntax:

pwledit [x_step [y_step]] vector

pwledit [x_step [y_step]] vector opt filename


pwledit displays one of the waveforms whose PWL fitting has been already

extracted (see commands pwlonwave or pwlongrid): upon this command is

activated, DWV plots the waveform specified by vector and its PWL extraction

on the graphic window. If the extraction was performed using the command

pwlonwave, the mouse cursor (white cross shaped) is positioned on the first

sample of the waveform, otherwise, if the command pwlongrid was used, the

cursor is positioned on the lower left corner of the graphic window.

pwledit uses all the buttons of the mouse: the left button (or first button), the right

button (or second button) and the center button (if the mouse has only two

buttons, the center one corresponds to the two buttons pressed simultaneously).

The first button moves one of the previously extracted PWL breakpoints through

the following sequence of actions:

1) point at the breakpoint to be moved,

2) press the first button of the mouse and move the marker to the new position,

3) release the button.

The center button adds or deletes breakpoints of the PWL extraction. To add a

breakpoint between two already extracted breakpoints, it is sufficient to point at

the new breakpoint and press the center button of the mouse. A breakpoint is

deleted by positioning the cursor on it and by pressing the center button.

The right button of the mouse is used to exit. If pressed, DWV restores the last

plotting window (in plot mode) active on the screen before the pwledit command.

Opt allows the user to save on a file all the data displayed on the graphic window

at the end of the pwledit session. The output format is related to a laser printer

(opt = -l) or a plotter (opt = -p). The file filename is created at the end of the edit

session in the current directory, before restoring the plot mode. The output file

can be sent to the printing device by means of the command plotexec. It is

Chapter 8 110


possible to add a title to the hardcopy using the command title before activating

the pwledit command.

If the PWL fitting of the waveform vector was performed using the command

pwlongrid, the optional parameters x_step and y_step, which are expressed in the

same unit currently assigned to the x-axis and y-axis taking the scale factor into

account, can be used to create a grid on the graphic window. The new breakpoints

will be automatically snapped to the nearest grid node.

8.4 PWLIST

Syntax:

pwlist


pwlist enables the pwlist system window and lists on it the contents of the PWL

list, in particular the identifiers of the vectors whose PWL fitting has been already

extracted.

The waveform names, sorted file by file, and the expression labels are user

selectable fields. If the graphic cursor is positioned within the information frame,

the selected field is displayed in reverse mode; pressing the left button of the

mouse causes the transfer of the selected field in the command window. The file

name is automatically added to the selection to avoid ambiguities. In case of

expression, its complete mathematical expression is also reported.

8.5 PWLSAVE

Syntax:

pwlsave vector [filename]


pwlsave stores on a file the information related to the PWL fitting of the

waveform vector extracted with the command pwlonwave or pwlongrid. The

Chapter 8 111


optional parameter filename specifies the name of the file used to save the

breakpoints. If omitted, the default name vector_file.pwl will be used, where

vector_file is the name of the graphic file containing the PWL-fitted waveform

vector.

If the PWL extraction of an expression generated in the current working session

has to be saved, the following procedure must be followed:

1) store the expression on a file with the command save,

2) load the expression file previously saved with the command load,

3) extract the PWL fitting (with the command pwlonwave or pwlongrid),

4) save the breakpoints with the command pwlsave.

This procedure guarantees to save the source waveform fitted with the PWL

extraction that is required, for example, by the command pwledit.

8.6 PWLFREE

Syntax:

pwlfree vector


pwlfree cancels the breakpoints stored in the PWL list related to the waveform

specified by vector.

8.7 PWLOAD

Syntax:

pwload filename


This command loads in the PWL list the information related to a PWL fitting of a

waveform previously extracted with the command pwlonwave or pwlongrid.

Chapter 8 112


DWV extracts the following information from the file filename (previously

generated by means of the pwlsave command):

- name of the graphic file and of the related waveform that has been used as

source of the PWL extraction,

- number of the extracted breakpoints,

- extraction type (0 for PWLONWAVE or 1 for PWLONGRID),

- abscissa of the first breakpoint,

- coordinates of each breakpoint.

Each breakpoint abscissa is given with reference to the abscissa of the first

breakpoint.

Upon selecting the command, DWV checks if the source waveform is already

available on memory. If not, a message is displayed on the command window and

the user must load the required graphic file containing the source waveform

before editing the PWL extraction.

Chapter 8 113


Chapter 8 114

Help and End of the Work Session DWV

Chapter 9

He lp and End o f the Work Sess ion

9.1 Help

9.2 Exit

9.3 Info

Chapter 9 115

Help and End of the Work Session DWV

9.1 HELP

Syntax:

help

help displays the contents of the file DWV.help, containing the command

explanations, in a text window.

9.2 EXIT

Syntax:

exit

exit ends the current DWV work session and returns the control to the Operative

System. Once the command is selected, the system asks for a confirmation. Type:

- Y to exit

- N to continue the work session.

The file DWV.history carrying the list of the last commands of the terminated

session is saved in the working directory and will be available at the next DWV

work session on that directory.

9.3 INFO

Syntax:

info

info displays the version of the software. The command is available by pop-up

menu only.

Chapter 9 116

Syntax of the Mathematical Expressions DWV

Chapter

10

Syntax o f the Mathemat i ca l Express ions

Chapter 10 117


DWV is able to execute commands that contain mathematical expressionsError:

Reference source not found operating on vectors or reals (in the last case DWV

works as a calculator). These functions require the user to follow some syntactic

rules in order to get correct results. The procedure is activated by means of one of

the commands plot, mplot, eyed or meyed with the expression to evaluate

specified as parameter. If a vector is present in the expression, the result is

displayed on the screen, otherwise, if all the elements of the expression are real

numbers, the numerical result is printed on the command window.

It is possible to use the four operators +, -, *, /. For example:

plot V(10) + 4.5 - 6

plot 5 * 3 - 60

The interpreter analyzes the expression from left to right giving priority to the

operators * and / with respect to + and -. The use of round brackets is allowed

and their contents are evaluated with priority. In case of real numbers, it is

necessary to separate any operator with a character SPACE to avoid ambiguities

of interpretation. In fact, the operation 5 - 3 if written without spaces, 5-3, is

interpreted as a filename. In this case the message "syntax error" is printed on the

command window. For example:

plot 5 * (6 - 7 / 4) - 44 * (65 - 1.33)

has to be used instead of

plot 5*(6-7/4)-44*(65-1.33)

The mathematical functions so far available are:

sin ---> sine Error: Reference source not found

cos ---> cosineError: Reference source not found

tan ---> tangentError: Reference source not found

ln ---> natural logarithmError: Reference source not found

log ---> logarithm base 10Error: Reference source not found

sqr ---> square Error: Reference source not found

sqrt ---> square rootError: Reference source not found

exp ---> exponential functionError: Reference source not found

Chapter 10 118


abs ---> absolute value of the argumentError: Reference source not found

avg ---> average of the argument Error: Reference source not found

Each of these functions requires an argument enclosed between round brackets.

The arguments of the trigonometric functions must be expressed in radians. The

function avg allows only one argument and makes sense only if the argument is a

vector of samples. Avg evaluates the average of the vector on its time window.

For example:

plot avg(V(10) * 5 / ( 3 + 1 ) )

plot avg(I(VDR,5))

The operation between two vectors requires that their sampling step is the same,

otherwise an error message is printed out. If the vectors have the same sampling

step but different number of samples, the expression is evaluated at the common

x-axis points, and, in any case, a warning message is issued.

Chapter 10 119


Chapter 10 120

Index DWV

INDEXAa_selections, 18

abs, 113

AUTO-YLIMIT command, 76

AUTOSPACING command, 78

avg, 113

axes setup, 71

B

b_selections, 18

BACKGROUND command, 97

beg-time parameter, 47

bit sequence, worst case, 54

bit-rate, 47

CCAT command (UNIX), 86

CLEAR command, 69

com (directory), 4

command window, 16

cos, 112

curent graphic file, 34

cursors (directory), 4

DDEFAXES command, 73

descharge waveforms, 68

DISPLIST command, 66

doc (directory), 4

EEDITFILE command, 37

editing PWL extractions, 104

environment, 4

EVAL command, 93

Index 121

Index DWV

evaluating waveforms, 93

exp, 112

expression file format, 10

expressions, mathematical, 45

EYE-DIAG command, 47

EYED command, 47

FFast Fourier Transform, 95

FFT command, 95

fields, 29

file, DWVcolormap, 4

file, DWVcomlas, 4

file, DWVcomplot, 4

file, DWVformat, 5; 85

filename color, 93

fin-time parameter, 54

format HP-GL, 86

freq parameter, 47

Ggraphic window, 16

GRID command, 77

grid offset, 81

grid setup, 71; 77

grid step, 82

Hhardcopy, 83

HARDCOPY command, 87

hardcopy format, 85

HP-GL format, 86

Iinput file format, 8

interpreter, 45

intersymbol interference, 52

Jjitter, 48

Index 122

Index DWV

KKILLCOPY command, 89

LLABEL command, 96

labeling, 96

LEYE command, 52

leyedata file, 57

LEYEFREE command, 59

LEYEINFO command, 55

LEYELOAD command, 60

LEYEMPLOT command, 55

LEYEPLOT command, 55

LEYESAVE command, 57

limit eye-diagram, 52

LIST command, 35

list system window, 35

ln, 112

LOAD command, 34

log, 112

LSDIR command, 92

LSEQSAVE command, 57

Mmarkers, 93

mathematical expressions, 45; 112

MEYED command, 49

MEYEDALL command, 51

MPLOTALL command, 42

PPANNING command, 64

panning step, 64

PANSTEP command, 66

pid (process identifier), 87

PLOT command, 45

PLOTALL command, 43

PLOTEXEC command, 86

PLOTSAVE command, 85

Index 123

Index DWV

plotter units, 85

plotting modes, 23

PRINT STP command, 88

PWL extraction, 101

PWLEDIT command, 104

PWLFREE command, 106

PWLIST command, 105

PWLOAD command, 106

PWLSAVE command, 105

SSAVE command, 35

SCANPLOT command, 43

SETGFILE command, 38

shifting waveforms, 64

SHOWGFILE command, 37

DWVcolormap file, 4

DWVcomlas file, 4

DWVcomplot file, 4

DWVformat file, 5; 85

sin, 112

slot-windows, 17

sqr, 112

sqrt, 112

STARTIME command, 69

startup (directory), 4

stopping hardcopies, 89

summary, selections menu, 19

swing parameter, 54

system windows, 29

Ttan, 112

TITLE command, 96

UUNLOAD command, 35

V

Index 124

Index DWV

vector descharge, 68

VIEWFILE command, 37

Wworst-case sequence, 54

Xx-range, y-range, 73

XAXIS command, 74

XLIMIT command, 75

XOFFSET command, 81

XSCALE command, 76

YYDELTA command, 82

YLIMIT command, 76

YOFFSET command, 81

ZZOOM command, 62

Index 125

dvw (digital wave viewer) user manual

Technology

dwv environment

commands input

standard graphic format

pwl input format

basic graphic presentation

graphic mode selections

commands conventions

xy plots