docs/wiki/geda-sn_readme.html

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  15 <h1 class="sectionedit1009"><a name="switcap_netlister_readme" id="switcap_netlister_readme">Switcap netlister README</a></h1>
  16 <div class="level1">
  17 <pre class="code">-----------------------------------------------------------------
  18 I.   What is this?
  19 -----------------------------------------------------------------
  20
  21 This archive contains a set of symbols and a netlister backend for the
  22 gEDA to drive SWITCAP simulations.  gEDA is the GNU EDA project and
  23 includes a schematic capture tool and a highly flexible netlister.
  24 The SWITCAP program is a switched capacitor circuit simulator.
  25
  26 -----------------------------------------------------------------
  27 II.  Overview
  28 -----------------------------------------------------------------
  29
  30 The basic steps involved with using gEDA as the frontend for SWITCAP
  31 simulations are:
  32
  33 - configure the gEDA symbol search path
  34 - set the gEDA netlister backend search path
  35 - create schematics of the circuit
  36 - create an analysis file
  37 - extract the netlist
  38 - run the SWITCAP simulation
  39
  40
  41 -----------------------------------------------------------------
  42 III.  Initial Setup
  43 -----------------------------------------------------------------
  44   1)  Set your symbol search path for gschem and gnetlist by adding
  45       the following line to the &#039;gschemrc&#039; and &#039;gnetlistrc&#039; files in
  46       your project directory.
  47
  48         (component-library &quot;/path/to/sym/switcap&quot;)
  49
  50       If those files do not exist, then create them.  You will need to
  51       replace /path/to/sym/switcap with the directory name where you
  52       have installed the .sym files.
  53
  54   2)  Set the search path for scheme files for gnetlist by adding the
  55       following line to your &#039;gnetlistrc&#039; file.
  56
  57         (scheme-directory &quot;/path/to/scheme&quot;)
  58
  59       You will need to replace /path/to/scheme with the path to where
  60       you have installed the gnet-switcap.scm file.
  61
  62   3)
  63
  64 -----------------------------------------------------------------
  65 IV.  Creating Schematics
  66 -----------------------------------------------------------------
  67
  68 --------------------
  69 A.  Required Symbols
  70 --------------------
  71
  72 This section assumes you are familiar with using gschem to create and
  73 edit schematics.  SWITCAP netlisting is only supported for the
  74 components contained in the SWITCAP symbol library as well as the
  75 ground symbol found in the &#039;power&#039; library which comes with gEDA.  All
  76 allowed SWITCAP elements except for subcircuits are supported.  You
  77 _must_ include the following elements on your schematic:
  78
  79 - one instance of the switcap-timing symbol.  This symbol will set the
  80   master clock period for your simulations.
  81
  82 - one or more instances of the switcap-clock symbol.  This symbol
  83   defines a clock with a particular phase and period.  The reference
  84   designator of the clock symbol is used by the switches to set what
  85   phase they switch on.
  86
  87 - one or more instances of the switcap-analysis symbol.  This symbol
  88   defines an analysis by specifying a file to include in the SWITCAP
  89   netlist.
  90
  91 --------------------
  92 B.  Optional Symbols
  93 --------------------
  94
  95 You can also optionally add the following SWITCAP special symbols to
  96 your schematic:
  97
  98 - zero or one instance of the switcap-title symbol.  This will add a
  99   TITLE: line to the SWITCAP netlist and will appear in the output
 100   file.
 101
 102 - zero or one instance of the switcap-options symbol.  By editing the
 103   OPTIONS attribute on this symbol you can set the various options
 104   which can be passed to SWITCAP.
 105
 106 --------------------
 107 C.  Net Names
 108 --------------------
 109
 110 When creating schematics to drive SWITCAP, you should name all nets
 111 that you wish to plot.  To avoid possible conflicts with unnamed nets,
 112 you should avoid using purely numerical names for nets because
 113 all unnamed nets will be assigned (somewhat randomly) numbers.
 114 SWITCAP limits the length of node names to 7 characters.
 115
 116 --------------------
 117 D.  Switches
 118 --------------------
 119
 120 When placing switches on your schematic, you will need to define
 121 which clock they are controlled with.  This is done by setting
 122 the clock attribute on the switch to the reference designator
 123 of the clock which should control it.
 124
 125 -----------------------------------------------------------------
 126 V.  Extracting the SWITCAP Netlist
 127 -----------------------------------------------------------------
 128
 129 To extract the SWITCAP netlist, run
 130
 131   gnetlist -g switcap -o test.scn file1.sch [file2.sch ...]
 132
 133 For the example file contained in this archive, you can run:
 134
 135   gnetlist -g switcap -o example.scn ckt.sch clocks.sch analysis.sch
 136
 137 The netlist will be left in example.scn.
 138
 139 -----------------------------------------------------------------
 140 VI.  Running SWITCAP
 141 -----------------------------------------------------------------
 142
 143 I typically use something like:
 144
 145   printf &quot;example.scn\nexample.out&quot; | sw
 146
 147 so I can use command history to rerun SWITCAP without having to
 148 manually type the file names each time.
 149
 150 Refer to the SWITCAP manual for more details.
 151
 152 </pre>
 153
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