NAME

     drawtiming — generate timing diagram from signal description

SYNOPSIS

     drawtiming [--verbose] [--scale factor] [--pagesize WxH] [--aspect] [--cell-height H]
                [--cell-width W] [--font-size pts] [--line-width W] --output target file ...

DESCRIPTION

     This application provides a command line tool for documenting hardware and software designs
     through ideal timing diagrams.  It reads signal descriptions from a text file with an
     intuitive syntax, and outputs an ideal timing diagram to an image file.  Notation typical of
     timing diagrams found in the Electrical Engineering discipline is used, including arrows
     indicating causal relationships between signal transitions.

     The options are as follows:

     --help      Show usage reminder.

     --verbose   Increase diagnostic output.

     --scale factor
                 Scale the diagram by the given factor.  The default scaling factor is 1.0.

     --pagesize WidthxHeight
                 Scale the diagram to fit given image size.

     --aspect    Maintain fixed aspect ratio if --pagesize given.

     --cell-height H
                 Height of the each signal in pixels. Default is 32.

     --cell-width W
                 Width for the time unit in pixels. Defaults is 64.

     --font-size pts
                 Font size in pts. Default is 18.

     --line-width W
                 Line width for drawings in pixels. Default is 1.

     --output target
                 The name and format of the output image is determined by target.

     file ...    The input files describe the signals to be diagrammed.  See the FILES and
                 EXAMPLES sections for a description of their format.

FILES

     The following is a technical description of the input file syntax and semantics.  If you are
     reading this for the first time, you may want to skip ahead to the EXAMPLES section.

     The input file consists of a series of statements describing the signal transitions during
     each clock period of the timing diagram.  Whitespace and comments following a ‘#’ are
     ignored.

     SIGNAL=VALUE  This statement changes the value of a signal at the beginning of the current
                   clock, and adds it to the list of signal dependencies.  The signal name may
                   consist of one or more words consisting of alphanumerics and underscores
                   joined by periods, ‘signal.name’, for example.  The signal value format is
                   described further on.

     SIGNAL        This statement adds a signal to the list of dependencies without changing its
                   value.

     Statements are separated by the following symbols:

     ,     The comma separator is used to separate statements without affecting the dependency
           list or clock (ie: the next statement will add to the dependency list).

     ;     The semicolon separator resets the list of dependencies without incrementing the clock

     .     The period separator resets the list of dependencies and increments the clock.

     =>    The "causes" separator renders dependency arrows based on the current list of
           dependencies and then resets the dependency list.

     -tD>  The "delay" separator renders a delay arrow from the last dependency with the
           annotation tD.

     Signal values are rendered according to the following rules:

     0, 1, true, false  A binary high/low signal.

     tick               A clock pulse which repeats.

     pulse              A one-shot clock pulse.

     X                  A don't care value.

     Z                  A tristate value.

     "ABC"              Any other alphanumeric token, or text enclosed in quotes is rendered as a
                        state.  For example, ‘"1"’, is rendered as a state, whereas, ‘1’, is
                        rendered as a high signal.

EXAMPLES

     Let's look at an example input file, and parse its meaning.

           POWER=0, FIRE=0, ARMED=0, LED=OFF, COUNT=N.
           POWER=1 => LED=GREEN.
           FIRE=1.
           FIRE => ARMED=1.
           FIRE=0.
           FIRE=1.
           FIRE, ARMED => LED=RED;
           FIRE => COUNT="N+1".

     This input file describes the changes in five signals over a period of seven clock cycles.
     The end of each clock cycle is indicated with a period.  For example, the following line
     indicates a single signal, named ‘FIRE’ became true during a clock cycle:

           FIRE=1.

     The first clock period of the input file provides the initial value for all signals to be
     diagrammed.  The signals will appear on the timing diagram in the order they first appear in
     the input file.  Signals are assumed to have the "don't care" value if their initial value
     is not given.

     Independent signal transitions which occur simultaneously are normally separated by commas.
     Since signals aren't normally expected to change simultaneously, the initial state is a good
     example of this:

           POWER=0, FIRE=0, ARMED=0, LED=OFF, COUNT=N.

     Dependencies can also be indicated for a signal transition.  Dependencies are rendered as
     arrows on the timing diagram from the last change in each dependency to the dependent signal
     transition.  Here, the previous change in the state of ‘FIRE’ causes a change in the ‘ARMED’
     signal.

           FIRE => ARMED=1.

     To indicate that a change in one signal causes an immediate change in another signal, list
     both signal changes in the same clock period:

           POWER=1 => LED=GREEN.

     For signal state changes with multiple dependencies, separate the dependencies with commas:

           FIRE, ARMED => LED=RED.

     Sometimes, a single dependency causes multiple independent signals to change.  Use a
     semicolon to start a new list of dependencies.  Modifying the previous line to indicate that
     ‘FIRE’ also causes ‘COUNT’ to increment yields:

           FIRE, ARMED => LED=RED;
           FIRE => COUNT="N+1".

     You can find this example and others along with their generated timing diagrams on the
     homepage for drawtiming at ‘http://drawtiming.sourceforge.net’.

DIAGNOSTICS

     Exit status is 0 on success, and 2 if the command fails.

COMPATIBILITY

     The drawtiming command has been tested on FreeBSD, Linux, and Cygwin.

AUTHORS

     This software package was written by Edward Counce <ecounce@users.sourceforge.net>
     Additional modifications by
     Salvador E. Tropea <set@users.sourceforge.net>
     Daniel Beer

BUGS

     None reported.