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  28 <h1><a name="switcap_netlister_readme" id="switcap_netlister_readme">Switcap netlister README</a></h1>
  29 <div class="level1">
  30 <pre class="code">-----------------------------------------------------------------
  31 I.   What is this?
  32 -----------------------------------------------------------------
  33
  34 This archive contains a set of symbols and a netlister backend for the
  35 gEDA to drive SWITCAP simulations.  gEDA is the GNU EDA project and
  36 includes a schematic capture tool and a highly flexible netlister.
  37 The SWITCAP program is a switched capacitor circuit simulator.
  38
  39 -----------------------------------------------------------------
  40 II.  Overview
  41 -----------------------------------------------------------------
  42
  43 The basic steps involved with using gEDA as the frontend for SWITCAP
  44 simulations are:
  45
  46 - configure the gEDA symbol search path
  47 - set the gEDA netlister backend search path
  48 - create schematics of the circuit
  49 - create an analysis file
  50 - extract the netlist
  51 - run the SWITCAP simulation
  52
  53
  54 -----------------------------------------------------------------
  55 III.  Initial Setup
  56 -----------------------------------------------------------------
  57   1)  Set your symbol search path for gschem and gnetlist by adding
  58       the following line to the &#039;gschemrc&#039; and &#039;gnetlistrc&#039; files in
  59       your project directory.
  60
  61         (component-library &quot;/path/to/sym/switcap&quot;)
  62
  63       If those files do not exist, then create them.  You will need to
  64       replace /path/to/sym/switcap with the directory name where you
  65       have installed the .sym files.
  66
  67   2)  Set the search path for scheme files for gnetlist by adding the
  68       following line to your &#039;gnetlistrc&#039; file.
  69
  70         (scheme-directory &quot;/path/to/scheme&quot;)
  71
  72       You will need to replace /path/to/scheme with the path to where
  73       you have installed the gnet-switcap.scm file.
  74
  75   3)
  76
  77 -----------------------------------------------------------------
  78 IV.  Creating Schematics
  79 -----------------------------------------------------------------
  80
  81 --------------------
  82 A.  Required Symbols
  83 --------------------
  84
  85 This section assumes you are familiar with using gschem to create and
  86 edit schematics.  SWITCAP netlisting is only supported for the
  87 components contained in the SWITCAP symbol library as well as the
  88 ground symbol found in the &#039;power&#039; library which comes with gEDA.  All
  89 allowed SWITCAP elements except for subcircuits are supported.  You
  90 _must_ include the following elements on your schematic:
  91
  92 - one instance of the switcap-timing symbol.  This symbol will set the
  93   master clock period for your simulations.
  94
  95 - one or more instances of the switcap-clock symbol.  This symbol
  96   defines a clock with a particular phase and period.  The reference
  97   designator of the clock symbol is used by the switches to set what
  98   phase they switch on.
  99
 100 - one or more instances of the switcap-analysis symbol.  This symbol
 101   defines an analysis by specifying a file to include in the SWITCAP
 102   netlist.
 103
 104 --------------------
 105 B.  Optional Symbols
 106 --------------------
 107
 108 You can also optionally add the following SWITCAP special symbols to
 109 your schematic:
 110
 111 - zero or one instance of the switcap-title symbol.  This will add a
 112   TITLE: line to the SWITCAP netlist and will appear in the output
 113   file.
 114
 115 - zero or one instance of the switcap-options symbol.  By editing the
 116   OPTIONS attribute on this symbol you can set the various options
 117   which can be passed to SWITCAP.
 118
 119 --------------------
 120 C.  Net Names
 121 --------------------
 122
 123 When creating schematics to drive SWITCAP, you should name all nets
 124 that you wish to plot.  To avoid possible conflicts with unnamed nets,
 125 you should avoid using purely numerical names for nets because
 126 all unnamed nets will be assigned (somewhat randomly) numbers.
 127 SWITCAP limits the length of node names to 7 characters.
 128
 129 --------------------
 130 D.  Switches
 131 --------------------
 132
 133 When placing switches on your schematic, you will need to define
 134 which clock they are controlled with.  This is done by setting
 135 the clock attribute on the switch to the reference designator
 136 of the clock which should control it.
 137
 138 -----------------------------------------------------------------
 139 V.  Extracting the SWITCAP Netlist
 140 -----------------------------------------------------------------
 141
 142 To extract the SWITCAP netlist, run
 143
 144   gnetlist -g switcap -o test.scn file1.sch [file2.sch ...]
 145
 146 For the example file contained in this archive, you can run:
 147
 148   gnetlist -g switcap -o example.scn ckt.sch clocks.sch analysis.sch
 149
 150 The netlist will be left in example.scn.
 151
 152 -----------------------------------------------------------------
 153 VI.  Running SWITCAP
 154 -----------------------------------------------------------------
 155
 156 I typically use something like:
 157
 158   printf &quot;example.scn\nexample.out&quot; | sw
 159
 160 so I can use command history to rerun SWITCAP without having to
 161 manually type the file names each time.
 162
 163 Refer to the SWITCAP manual for more details.
 164
 165
 166 </pre>
 167
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