64 lines
3.5 KiB
ReStructuredText
64 lines
3.5 KiB
ReStructuredText
KiCAD Security Mesh Generator
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=============================
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.. image:: kicad-mesh-result-large.png
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:width: 800
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:alt: A screenshot of KiCAD showing a PCB security mesh generated by KiMesh.
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This repository contains KiMesh, a KiCAD pcbnew plugin that generates security mesh traces on a KiCAD PCB.
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Installation
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------------
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KiMesh has two parts: The pcbnew plugin that generates the traces, and the magic footprints that you use to tell the
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plugin how many traces of which dimensions to generate where.
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To install the plugin, copy the "kimesh" directory into your KiCAD installation's scripting plugin folder. Usually, this
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is `~/.config/kicad/scripting/plugins/` for KiCAD stable installations or
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`~/.config/kicad/[major version].99/scripting/plugins/` for nightly builds. On Windows, these paths can be found in your
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user account's `AppData/Roaming` directory.
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To install the footprint libraries, the easiest way is to download the library zip from the project's repo
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`[link] <https://git.jaseg.de/kimesh.git/plain/mesh_footprints.tar.xz?h=main>`__, unpack it to your project folder, and
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add the unpacked libraries as project-specific libraries through KiCad's library management thingy.
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Usage
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-----
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To work, KiMesh requires four things:
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1. An area free of other features such as footprints or traces where to generate the mesh.
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2. One or more "graphic polygons" on a drawing layer that specify the area of the mesh.
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3. A closed board outline on the `Edge.Cuts` layer.
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4. One of the magic footprints from the KiMesh anchor library that defines the mesh's number of wires and their
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dimensions, and tells KiMesh where to start the mesh and in which direction to start it.
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You can choose any layer for the outline polygons, such as the pre-defined `User.Eco1` or `User.X` layers, or you can
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define your own. You just have to select that layer later in KiMesh's generator dialog. Note that KiMesh only processes
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graphic polygons on that layer, and ignores other shapes such as lines, rectangles or circles. You can still use other
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shapes, but you have to manually convert them to polygons before running KiMesh. To convert other shapes to
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a polygon, select them, open the context menu with a right click, then choose the "Create from Selection 🞂 Create
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Polygon from Selection" entry. For rectangles or circles, use the "Use Centerlines" option. For lines or arcs, use the
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"Create bounding hull" option.
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Place the magic anchor footprint on the outline of the mesh's shape polygons so that you have space to route out the
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traces. The anchor footprint has an arrow on the `F.Fab` layer that indicates in which direction the mesh will be
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generated.
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I recommend adding the mesh to the schematic with one of KiCad's built-in `Connector_02xN_Top_Bottom` footprints. For a
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mesh with k wires, choose a symbol with two rows of 2k pins each. For instance, for two mesh wires, choose
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`Connector_02x04_Top_bottom`. Then assign one of the magic footprints to that symbol. To avoid DRC warnings, join the
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two halves of the mesh on the output side of the footprint. That's the right side in default orientation, where the
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higher-numbered pins are.
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.. image:: screenshot-mesh-schematic.png
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:width: 800
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:alt: A screenshot of the connector footprint mentioned in the previous paragraph, shown conencted up as described in
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KiCad's schematic editor.
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Theory of operation
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-------------------
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I have published a post_ on my blog on the theory of operation behind KiMesh.
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.. _post: https://blog.jaseg.de/posts/kicad-mesh-plugin/
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