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gnucap:user:netlist_import_and_export:geda [2025/04/09 14:02] felixs created |
gnucap:user:netlist_import_and_export:geda [2025/04/25 04:51] (current) felixs Implicit connections |
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| == The value attribute == | == The value attribute == | ||
| - | TODO | + | The value attribute in gEDA translates to parameter assignments. For example |
| + | <code>C resistor-1.sym [..] | ||
| + | [..] device=resistor [..] refdes=r1 [..] | ||
| + | T 1 2 3 4 [..] | ||
| + | value=r=1k tnom=17 tc0=3</code> | ||
| + | |||
| + | is represented as | ||
| + | |||
| + | <code> | ||
| + | resistor #(.r(1k), .tnom(17), .tc0(3)) r1( [..] ); | ||
| + | </code> | ||
| + | |||
| + | A value string that lacks parameter names is assigned by position, e.g. ''value=1 2 3'' will be turned into ''#(1,2,3)''. | ||
| + | |||
| + | |||
| + | == Implicit connections == | ||
| + | |||
| + | A symbol instance that represents a device may have multiple ''net'' attributes with a value like A:B,C,D, see [[https://lepton-eda.github.io/lepton-manual.html/net_003d-attribute-mini_002dHOWTO.html|Lepton manual]]. These are translated to port assignments, and mix with other port assignments. For example | ||
| + | <code>some_device #() my_refdes(.B(A), .B(A), .B(A), [..] .other(n17),[..]);.</code> | ||
| + | |||
| + | Sometimes those "net" connections correspond to named visible pins inside the symbol. The Lepton manual addresses the situation as follows. | ||
| + | //Creating a ‘net=’ attribute which associates a signal name with a pin which is already visible on the symbol, is probably a bad idea. This does work, but all the ramifications have not been explored yet.// | ||
| + | |||
| + | The ''bad idea'' finds use in "rail" devices referring that //specify power, ground, and/or arbitrary nets//. For example, | ||
| + | a gnd-1.sym instance has a port named "1" and a "net=GND:1" attribute. If port "1" is connected to a (positioned) node ''n42'', we represent the instance as | ||
| + | <code>net #() myground0(.\1 (n42), .rail(GND));.</code> | ||
| + | Using a "net" special device is consistent with use in gEDA, since ''gnd-1.sym'' is not meant to carry a "device" attribute. The additional "GND" node connects all gnd-1.sym instances, following the "net" logic, as intended. The name of the second port, "rail", is made up, for now. | ||