docs/wiki/geda-gnetlist_ug-hierarchy.html

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  12 <a href=.>start</a>&nbsp;=>&nbsp;<a href=geda-gnetlist_ug.html>gnetlist_ug</a></br>
  13 <div class="table sectionedit1"><table class="inline">
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  15                 <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>
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  18 <!-- EDIT1 TABLE [1-175] -->
  19 <h2 class="sectionedit2" id="hierarchy">Hierarchy</h2>
  20 <div class="level2">
  21
  22 <p>
  23 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!
  24 </p>
  25
  26 <p>
  27 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&#039;s schematic file.
  28 </p>
  29
  30 <p>
  31 Subcircuit symbols are loaded from the symbol library as normal.  Subcircuit schematics are loaded from the <em>source library</em>.
  32 </p>
  33 <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.
  34 </div>
  35 </div>
  36 <!-- EDIT2 SECTION "Hierarchy" [177-1039] -->
  37 <h3 class="sectionedit3" id="hierarchical_ports">Hierarchical ports</h3>
  38 <div class="level3">
  39
  40 <p>
  41 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&#039;s nets, gnetlist will look for the first pin on a component which has a “<code>refdes=</code>” attribute that matches the port&#039;s name.  You can normally use the “in-1.sym” and “out-1.sym” symbols from the generic “Input/Output” symbol library for this.
  42 </p>
  43
  44 </div>
  45 <!-- EDIT3 SECTION "Hierarchical ports" [1040-1549] -->
  46 <h3 class="sectionedit4" id="renaming_components_and_nets">Renaming components and nets</h3>
  47 <div class="level3">
  48
  49 <p>
  50 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&#039;s name as a prefix.
  51 </p>
  52
  53 <p>
  54 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”.
  55 </p>
  56
  57 </div>
  58 <!-- EDIT4 SECTION "Renaming components and nets" [1550-] --></body>
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