<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html> <head> <title></title> <link rel="stylesheet" media="screen" type="text/css" href="./style.css" /> <link rel="stylesheet" media="screen" type="text/css" href="./design.css" /> <link rel="stylesheet" media="print" type="text/css" href="./print.css" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> </head> <body> <div class="table sectionedit2142"><table class="inline"> <tr class="row0"> <td class="col0 leftalign"> « <a href="geda-gnetlist_ug-basic_netlisting.html" class="wikilink1" title="geda-gnetlist_ug-basic_netlisting.html">Basic netlisting</a> </td><td class="col1 centeralign"> <strong><a href="geda-gnetlist_ug.html" class="wikilink1" title="geda-gnetlist_ug.html">gEDA gnetlist User Guide</a></strong> </td><td class="col2 rightalign"> <a href="geda-gnetlist_ug-slotting.html" class="wikilink1" title="geda-gnetlist_ug-slotting.html">Slots and slotting</a> » </td> </tr> </table></div> <!-- EDIT2142 TABLE [1-175] --> <h2 class="sectionedit2143"><a name="hierarchy" id="hierarchy">Hierarchy</a></h2> <div class="level2"> <p> gnetlist has support for <em>hierarchical schematics</em>. These are schematic diagrams that include other schematic diagrams as <em>subcircuits</em>. This can be very useful for designs that use the same circuit multiple times, or for re-using a circuit in multiple designs. Subcircuits can in turn contain other subcircuits! </p> <p> Each subcircuit schematic diagram needs to have a subcircuit symbol associated with it. The ”<code>device=</code>” attribute on a subcircuit symbol is ignored. The ”<code>source=</code>” attribute should be used to specify the name of the subcircuit's schematic file. </p> <p> Subcircuit symbols are loaded from the symbol library as normal. Subcircuit schematics are loaded from the <em>source library</em>. </p> <p> <p><div class="notetip">See <a href="geda-gnetlist_ug-config.html" class="wikilink1" title="geda-gnetlist_ug-config.html">Configuring gnetlist</a> for details of how to control where gnetlist looks for subcircuit schematic files. </div></p> </p> </div> <!-- EDIT2143 SECTION "Hierarchy" [177-1039] --> <h3 class="sectionedit2144"><a name="hierarchical_ports" id="hierarchical_ports">Hierarchical ports</a></h3> <div class="level3"> <p> The pins on a subcircuit symbol define the <em>ports</em> where designs that include the circuit can connect to it. Each port should be named using a ”<code>pinlabel=</code>” attribute. To define the points where a port attaches to the subcircuit's nets, gnetlist will look for the first pin on a component which has a ”<code>refdes=</code>” attribute that matches the port's name. You can normally use the “in-1.sym” and “out-1.sym” symbols from the generic “Input/Output” symbol library for this. </p> </div> <!-- EDIT2144 SECTION "Hierarchical ports" [1040-1549] --> <h3 class="sectionedit2145"><a name="renaming_components_and_nets" id="renaming_components_and_nets">Renaming components and nets</a></h3> <div class="level3"> <p> Each subcircuit symbol placed into a schematic must have a ”<code>refdes=</code>” attribute attached to it. This is the name of the <em>subcircuit instance</em>. In order to uniquely identify components and nets in each instance of a hierarchical subcircuit, gnetlist will rename them using the subcircuit's name as a prefix. </p> <p> For example, consider a subcircuit that contains a component with ”<code>refdes=U1</code>” and a net with ”<code>netname=FEEDBACK</code>”. Now, suppose the subcircuit symbol is placed in a schematic and an attribute ”<code>refdes=A1</code>” is attached to it. When the schematic is processed using gnetlist, gnetlist will rename the component to “A1/U1” and rename the net to “A1/FEEDBACK”. </p> </div> <!-- EDIT2145 SECTION "Renaming components and nets" [1550-] --></body> </html>
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