72 lines
2.3 KiB
HTML
72 lines
2.3 KiB
HTML
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<!DOCTYPE html>
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<html>
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<head>
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<title>SYMBOLS</title>
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<link rel="stylesheet" type="text/css" href="xschem_man.css" />
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<style type="text/css">
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/* Local styling goes here */
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p{padding: 15px 30px 10px;}
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</style>
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</head>
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<body>
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<!-- start of slide -->
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<div class="content">
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<!-- navigation buttons -->
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<a href="xschem_elements.html" class="prev">PREV</a>
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<a href="xschem_man.html" class="home">UP</a>
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<a href="xschem_properties.html" class="next">NEXT</a>
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<!-- slide title -->
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<h1>SYMBOLS</h1><br>
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<p>
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The best way to understand how a symbol is defined is to analyze an existing one.
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Load a test schematic (for example <kbd>test.sch</kbd>). Let's consider the
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resistor symbol. Use the <kbd>Insert</kbd> key to place the <kbd>devices/res.sym</kbd> symbol.
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</p>
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<img src="xschem_insert.png">
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<p>
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Use the file selector dialog to locate <kbd>res.sym</kbd>.
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</p>
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<img src="building_symbol_01.png">
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<p>
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Now select the resistor by left-clicking on it (it will turn to grey color)
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</p>
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<img src="building_symbol_02.png">
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<p>
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After selecting the component (component is an instance of a symbol)
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descend into its symbol definition
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by pressing the <kbd>'i'</kbd> key. XSCHEM will load the
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<kbd>devices/res.sym</kbd> file and show it in
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the drawing window. Before descending it asks if you want to save
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the parent schematic drawing
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before loading the resistor symbol. Answer 'yes'.
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</p>
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<img src="building_symbol_03.png">
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<p>
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The image above is the 'symbol definition', you can now select individual graphic elements that
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represent the symbol, lines, rectangles and text.
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Normally a symbol contains some pins, these are just rectangles drawn on the 'pin' layer, and some
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graphics / descriptive text. Another fundamental part of symbols are properties.
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Properties are text strings that define attributes of the symbol, for example:
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</p>
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<ul>
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<li>The name of the connection pins</li>
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<li>The type of the symbol (spice primitive, subcircuit, documentation)</li>
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<li>The format of the spice/verilog/VHDL netlist for the symbol</li>
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</ul>
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<p>
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We will return on symbols after explaining properties.
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</p>
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<!-- end of slide -->
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<div class="filler"></div>
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</div>
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<!-- frame footer -->
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<iframe seamless src="xschem_footer.html" class="footer_iframe" >
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</body>
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</html>
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