* gnucap:manual:commands

gnucap:manual:commands:ac

Purpose Performs a small signal, steady state, AC analysis. Sweeps frequency. Syntax ac {//options// ...} //start stop stepsize// {//options// ...} Comments The “ac” command does a linear analysis about an operating point. It is absolutely necessary to do an “op” analysis first on any nonlinear circuit. Not doing this is the equivalent of testing it with the power off.

gnucap:manual:commands:alarm

Purpose Select points in the circuit to check against user defined limits. Syntax alarm alarm mode points ... ... alarm mode + points ... ... alarm mode - points ... ... alarm mode clear Comments The `alarm' command selects points in the circuit to check against limits. There is no output unless the limits are exceeded. If the limits are exceeded a the value is printed.

gnucap:manual:commands:alter

Purpose Quickly change a component value. Syntax alter partlabel=value ... modify partlabel=value ... Comments This command quickly changes the value of a component. It is restricted to simply changing the value. If several components have the same label or if wildcard characters are used, all are changed.

gnucap:manual:commands:attach

Purpose Load a plugin, or a set of plugins. Syntax {attach|load} [options] path Comments A file or directory is specified using a path. A path starting with / is absolute. A path starting with . is relative to the current working directory. Other paths refer to the first hit relative to a directory listed in GNUCAP_PLUGPATH.

gnucap:manual:commands:build

Purpose Builds a new circuit, with Spice syntax. Syntax build Comments “Build” lets you enter the circuit from the keyboard. The prompt changes to > to show that the program is in the build mode. At this point, type in the circuit components in Spice netlist format.

gnucap:manual:commands:chdir

Purpose Changes or displays the current directory name. Syntax chdir {path} cd {path} Comments Change the current directory to that specified by path. See your system manual for complete syntax. If no argument is given the current directory is displayed.

gnucap:manual:commands:dc

Purpose Performs a nonlinear DC steady state analysis, and sweeps the signal input, a component value or a parameter value. Components must be of type “element”, such as voltage/current sources and resistors. Sweeping parameters that are used to control expansion (binning or generate) will not trigger re-expansion, and hence might lead to unexpected results.

gnucap:manual:commands:delete

Purpose Remove a line, or a group of lines, from the circuit description. Syntax delete label ... delete allclear Comments To delete a part, by label, enter the label. (Example `DEL R15'.) Wildcards `*' and `?' are allowed, in which case, all that match are deleted.

gnucap:manual:commands:edit

Purpose Use your editor to change the circuit. Syntax edit edit file Comments The edit command runs your editor on a copy of the circuit in memory, then reloads it. Edit file runs your editor on the specified file. If you are only changing a component value, the modify command may be easier to use.

gnucap:manual:commands:end

“end” command When run in batch mode from the shell, the END command cleans up and exits the program. In script mode (< command) it ends the script and returns to the program prompt. In interactive mode it exits the program.

gnucap:manual:commands:eval

Purpose Check and evaluate an expression. Syntax eval expression Comments The eval command evaluates an expression and prints the result as a number. Examples gnucap> param a={b+c+7} gnucap> eval a parameter b+c+7 has no value parameter b+c+7 has no value a= NA gnucap> param b=c+3 gnucap> param c=4 gnucap> eval a a= 18. gnucap> eval b+c (b + c)= 11. gnucap>

gnucap:manual:commands:exit

Purpose Terminates the program. Syntax exit quit Comments Be sure you have saved everything you want to!

gnucap:manual:commands:fault

Purpose Temporarily change a component value. Syntax fault partlabel=value ... unfault Comments This command quickly changes the value of a component, usually with the intention that you will not want to save it. If you apply this command to a nonlinear or otherwise strange part, it becomes ordinary and linear until the fault is removed.

gnucap:manual:commands:fourier

Purpose Performs a nonlinear time domain (transient) analysis, but displays the results in the frequency domain. Syntax fourier start stop stepsize {options ...} Start, stop, and stepsize are frequencies. Comments This command is slightly different and more flexible than the SPICE counterpart. SPICE always gives you the fundamental and 9 harmonics. Gnucap will do the same if you only specify one frequency. SPICE has the probes on the same line. Gnucap requires you to specify the probes with…

gnucap:manual:commands:freeze

Purpose “Freeze” to a point in time. Remember circuit voltages and currents. Syntax freeze unfreeze Comments After the freeze command, the transient and fourier analysis will continue from the values that were kept by the freeze command, instead of progressing every time.

gnucap:manual:commands:generator

Purpose Sets up an input waveform for transient and Fourier analysis. Emulates a laboratory type function generator. Syntax generator {option-name=value ...} Comments This command sets up a singal source that is conceptually separate from the circuit. To use it, make the value of a component “generator(1)”, or substitute a scale factor for the parameter.

gnucap:manual:commands:get

Purpose Gets an existing circuit file, but does not run it, after clearing memory. Start over. Set up for interactive operation. Syntax get filename Comments The first comment line of the file being read is taken as the `title'. See the title command.

gnucap:manual:commands:include

Purpose Include a file, directly, as is. Syntax include filename Comments The file is included as is. If you are running interactive, it is as if you typed in what is in the file. If you are running in a batch mode, or including a file from another file, it is as if you did a copy and paste into that file.

gnucap:manual:commands:lib

Purpose Selective “library” include, and mark sections of a library. Syntax lib section-name lib file-name section-name Comments This command takes two forms: The first form is to mark a section of a file, with a name, so it can be selectively included. The section ends with a line ”.endl”.

gnucap:manual:commands:list

Purpose Lists the circuit in memory. Syntax list {label ...} list {label - label} Comments Plain list will list the whole circuit on the console. List with a component label asks for that one only. Wildcards are supported: ? matches any character, once. * matches zero or more of any character.

gnucap:manual:commands:load

Purpose Load and unload plugins. Syntax load public-model.so load ./my-model.so unload ./my-model.so Comments The load command loads a compiled plugin module. Plugins can be used to arbitrarily extend gnucap. You can add models, commands, functions, measurements, and anything else.

gnucap:manual:commands:log

Purpose Saves a copy of your keyboard entries in a file. Syntax log file log >> file log Comments The `>>' option appends to an existing file, if it exists, otherwise it creates one. Files can be nested. If you open one while another is already open, both will contain all the information.

gnucap:manual:commands:measure

Purpose Make measurements on a circuit, based on stored data. Syntax measure param-name = measurefunction(args) Comments The “measure” command sets parameters, like the “parameter” command, but the value after a measure is a number. It is used to make measurements on a circuit, such as slew rate, crossings, or average value.

gnucap:manual:commands:op

Purpose Performs a nonlinear DC steady state analysis, with no input. If a temperature range is given, it sweeps the temperature. Syntax op start stop stepsize {options ...} Comments There are substantial extensions beyond the capabilities of the SPICE op command.

gnucap:manual:commands:options

Purpose Sets options, iteration parameters, global data. Syntax options options option-name value ... Purpose Sets options, iteration parameters, global data. Comments Typical usage is the name of the item to set followed by the value. The bare command `options' displays the values.

gnucap:manual:commands:outfile

Purpose Saves a copy of all program output (except help) in a file. Syntax > file >> file > Comments > creates a new file for this output. If the file already exists, the old one is lost, and replaced by the new one. >> appends to an existing file, if it exists, otherwise it creates one.

gnucap:manual:commands:parameter

Purpose Set and view parameters. Syntax param parameter param param-name value ... parameter param-name value ... Comments The bare command param lists all defined parameters and their values. The value may be a number, the name of another parameter, or an expression. If it is another parameter, eventually it must resolve to a number. This depth can be set by the option recursion which has a default value of 20. The depth is limited to prevent infinite recursion.

gnucap:manual:commands:pause

Purpose Suspend batch mode. Wait for the user to hit a key. Syntax pause comment Status This command does not work on all systems, due to buffering of console i/o. Comments Prints Continue? and waits for a key hit. Type `n', `N', escape or control-c to terminate the batch mode. Type anything else to continue.

gnucap:manual:commands:plot

Purpose Select points in the circuit for graphic output. Select graphic output. Syntax plot plot mode points ... ... plot mode + points ... ... plot mode - points ... ... plot mode CLEAR Status The plotting leaves something to be desired. Only two signals can be plotted at a time. The output file is corrupt when plotting is on.

gnucap:manual:commands:print

Purpose Select points in the circuit for tabular output. Select tabular output. Syntax print print mode points ... ... print mode + points ... ... print mode - points ... ... print mode CLEAR Comments The `print' command selects where to look at the circuit, or where to hook the voltmeter (ammeter, watt meter, ohm meter, etc.) probe.

gnucap:manual:commands:save

Purpose Saves the circuit to a file. Syntax save filename {options ...} Comments The file is in an ASCII format, so the list may be used as part of a report. The format used depends on the “language” option, which could use a plugin to provide any format. “Spice”, “Spectre” and “Verilog” formats are supported in the standard installation.

gnucap:manual:commands:status

Purpose Shows information on how the system resources are being utilized. Syntax status status notime Comments The notime option omits times but prints everything else.

gnucap:manual:commands:store

Purpose Select points in the circuit to store for postprocessing. Syntax store store mode points ... ... store mode + points ... ... store mode - points ... ... store mode CLEAR Comments The “store” command selects probes to store for postprocessing, such as measures.

gnucap:manual:commands:sweep

Purpose Sweep a component (or group of components) over a range. Set up a loop for iteration. Syntax sweep {stepcount} partlabel=range ... Comments This command is considered obsolete, but the replacement is not working yet. This command begins a loop which will sweep a component or group of components.

gnucap:manual:commands:temp

Purpose Views and sets the temperature, with SPICE compatible syntax. Syntax temperature temperature value Comments With no value, it prints the temperature. With a value, it is equivalent to “.option temperature=value”. The real purpose of this command is Spice compatibility.

gnucap:manual:commands:title

Purpose View and create the heading line for printouts and files. Syntax title title a line of text Comments There is a header line at the beginning of every file, to help you identify it in the future. This command sets up what it says. It also sets up a heading for printouts and graphs.

gnucap:manual:commands:transient

Purpose Performs a nonlinear time domain (transient) analysis. Syntax transient start stop stepsize {options ...} transient stepsize stop start {options ...} Comments The probes to look at must have been previously selected by the print or plot command.

gnucap:manual:commands:width

Purpose Set input and output width. Syntax width {IN=value} {OUT=value} Comments The `width' command is the same as the `options' command. It is provided for SPICE compatibility. SPICE uses width to set two parameters: in and out, which we set with the options command.