docs/wiki/geda-pcb_layers.html

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  15 <h2 class="sectionedit1510"><a name="improvements_not_contained_in_the_new_concept" id="improvements_not_contained_in_the_new_concept">Improvements not contained in the new concept</a></h2>
  16 <div class="level2">
  17
  18 <p>
  19 “New layout” templates and wizards. (instead of defaulting to 4&times;4 8-layer)
  20 </p>
  21
  22 <p>
  23 Ability to hook into layer exporters (i.e. thindraw as a HID)
  24 </p>
  25
  26 <p>
  27 Also, trim polygons against “outline” layer.  Fix polygons in general.
  28 </p>
  29
  30 </div>
  31 <!-- EDIT1510 SECTION "Improvements not contained in the new concept" [1-270] -->
  32 <h1 class="sectionedit1511"><a name="new_concept_proposal" id="new_concept_proposal">New concept proposal</a></h1>
  33 <div class="level1">
  34
  35 </div>
  36 <!-- EDIT1511 SECTION "New concept proposal" [271-305] -->
  37 <h2 class="sectionedit1512"><a name="old_concept" id="old_concept">Old concept</a></h2>
  38 <div class="level2">
  39
  40 <p>
  41 There are “Layer groups” which contain “conductive layers”. One “Layer group” is actually one “physical layer”.
  42 There is max 10 layer groups. Number of layers is 16 + 2 silk screen layers. Layers have no “type”.
  43 </p>
  44
  45 <p>
  46 <code>Layer group:<br/>
  47
  48 Number<br/>
  49
  50 Numbers of layers contained<br/>
  51
  52 <br/>
  53
  54 Layer:<br/>
  55
  56 Name<br/>
  57
  58 Contained lines, arcs, polygons,…<br/>
  59
  60 Rtree of contained ^^^^<br/>
  61
  62 Visibility flag<br/>
  63
  64 Color<br/>
  65
  66 Selected color<br/>
  67
  68 Attributes<br/>
  69
  70 </code>
  71 </p>
  72
  73 </div>
  74 <!-- EDIT1512 SECTION "Old concept" [306-741] -->
  75 <h2 class="sectionedit1513"><a name="new_concept" id="new_concept">New concept</a></h2>
  76 <div class="level2">
  77
  78 <p>
  79 In the next part terms “physical layer” and “layer” are used. It can be changed to better names. Having just “layer” for
  80 “physical layer” and something else for “layer” will be great. Would “surface” go? Layer for one layer on PCB and surface for
  81 one drawing surface.
  82 </p>
  83
  84 <p>
  85 Layers are contained in a linked list, so there is no bounds on the number of them. “Physical layers” should probably be also
  86 in a linked list.
  87 </p>
  88
  89 <p>
  90 The Z-order of “physical layers” and “layers” is determined by the order in linked list and in layout file.
  91 </p>
  92
  93 <p>
  94 Active “layer” of each type is represented as pointer in “physical layer”. There is
  95 an array of size “number of layer types”, pointer on right place is the active layer.
  96 There is no need to have an active layer of each type.
  97 </p>
  98
  99 <p>
 100 One “physical layer” can be marked as “top” and one as “bottom”, so new footprints have some default layers assignment.
 101 This marks are useful just for footprint importing, there is no other use for them.
 102 </p>
 103
 104 <p>
 105 When adding anything (components, lines, polygons), all parts goes to the active layer of the right type for current “physical layer”.
 106 So line is added to active “conductive layer”, its mask to active “mask layer”,…. If there is no such layer, nothing happens.
 107 If the current layer is not conductive, something else can happen. Like adding polygon to “mask layer” will just mask/unmask that part….
 108 </p>
 109
 110 <p>
 111 There are two types of colors. The ones defined in application preferences and the ones defined in layout file.
 112 User can select to see any of the sets.
 113 </p>
 114
 115 <p>
 116 Colors in preferences are assigned to layer names, not layer numbers.
 117 </p>
 118
 119 <p>
 120 There is no concept of “layer number” everything is referred by name or pointer.
 121 </p>
 122
 123 <p>
 124 Each “physical layer” has Dimension property and can also have an Outline layer.
 125 The difference is, that NOTHING can be drawn out of dimension. The Outline is just
 126 hint how to manufactor the board. The Dimension is just one rectangle, Outline can have any
 127 shape. This Dimension property should replace the “Board dimension” currently defined in preferences.
 128 </p>
 129
 130 <p>
 131 Gerber output names will contain “physical layer” name.
 132 </p>
 133
 134 <p>
 135 The “Show Pin/Pads/Vias” flags in “Physical layer” is just inspecting and printing use.
 136 It doesn&#039;t hurt to have and can aid documentation generation.
 137 </p>
 138
 139 <p>
 140 <code>Physical layer:<br/>
 141
 142 Name ← this will be used in gerber export<br/>
 143
 144 Dimentions ← layer doesn&#039;t have to be across whole board<br/>
 145
 146 Attributes ← we can come up with a list of “expected attributes” like “permittivity, thickness,..”<br/>
 147
 148 Flags ← some “physical layer” wide flags<br/>
 149
 150 Layers ← linked list of layers in this “physical layer”<br/>
 151
 152 Pointer to layers ← linked list of all layers in this physical layer<br/>
 153
 154 Array of pointers to “active layers”<br/>
 155
 156 <br/>
 157
 158 Layer:<br/>
 159
 160 Name<br/>
 161
 162 Placement list ← Contained lines, arcs, polygons,…<br/>
 163
 164 Rtree of contained ^^^^<br/>
 165
 166 Flag ← flags described below<br/>
 167
 168 Type ← type list below<br/>
 169
 170 Color<br/>
 171
 172 Attributes<br/>
 173
 174 Pointer for linked list of “layers”<br/>
 175
 176 Pointer for linked list contained in “physical layer”<br/>
 177
 178 <br/>
 179
 180 Layer types:<br/>
 181
 182 Conductive ← the only conductive layer<br/>
 183
 184 Mechanical ← some additional non-conductive stuff<br/>
 185
 186 Outline ← outline of board<br/>
 187
 188 Silk ← Texts, component oulines,…<br/>
 189
 190 Mask ← mask on the board<br/>
 191
 192 Paste ← solder paste definition<br/>
 193
 194 Countryard ← component spacing definition<br/>
 195
 196 Rat<br/>
 197
 198 <br/>
 199
 200 Physical layer flags:<br/>
 201
 202 Show Pin/Via/Pads ← Show/Hide Pin/Via/Pads, 3 separate flags – NOT SAVED, the one in “Layer” is saved<br/>
 203
 204 <br/>
 205
 206 Layer flags:<br/>
 207
 208 Visible ← Show/Hide this layer – just temporal use, NOT SAVED<br/>
 209
 210 Show Pin/Via/Pads ← 3 separate flags, On some layers for special purpose it make sense to not include Via/Pin/Pads<br/>
 211
 212 Negativness ← Layer is negative layer<br/>
 213
 214 </code>
 215 </p>
 216
 217 </div>
 218 <!-- EDIT1513 SECTION "New concept" [742-4385] -->
 219 <h2 class="sectionedit1514"><a name="object_placements" id="object_placements">Object &amp; Placements</a></h2>
 220 <div class="level2">
 221
 222 <p>
 223 Each object is composed of 2 parts. One is &#039;description of the object&#039;. This is specific for the type of the object.
 224 </p>
 225
 226 <p>
 227 The other is &#039;placement of the object&#039;. This is common to all object.
 228 </p>
 229
 230 <p>
 231 It is possible to have more than one placement of single object.
 232 </p>
 233
 234 <p>
 235 There are &#039;shared copy&#039; and &#039;copy on write&#039; possibilities.
 236 </p>
 237
 238 <p>
 239 <code>
 240 Placement object:<br/>
 241
 242 Coordinates<br/>
 243
 244 Layer<br/>
 245
 246 Flags<br/>
 247
 248 ReferenceCounter<br/>
 249
 250 Pointer to the object<br/>
 251
 252 Pointer to composite ← when I am at some composite<br/>
 253
 254 Pointer to next object ← next object in the composite<br/>
 255
 256 <br/>
 257
 258 Placement flags:<br/>
 259
 260 Orientation<br/>
 261
 262 CopyOnWrite<br/>
 263
 264 </code>
 265 </p>
 266
 267 </div>
 268 <!-- EDIT1514 SECTION "Object & Placements" [4386-4992] -->
 269 <h2 class="sectionedit1515"><a name="composite_objects" id="composite_objects">Composite objects</a></h2>
 270 <div class="level2">
 271
 272 <p>
 273 Composite is an object composed of multiple other object. Composite can be an element of another composite.
 274 </p>
 275
 276 <p>
 277 Footprints, sub-layouts and vias are just composite objects.
 278 </p>
 279
 280 <p>
 281 All elements of composite object has placement relative to the origin of the composite.
 282 </p>
 283
 284 <p>
 285 <code>
 286 Composite object:<br/>
 287
 288 Type ← type list below<br/>
 289
 290 Attributes<br/>
 291
 292 Linked list of placement objects<br/>
 293
 294 <br/>
 295
 296 Composite types:<br/>
 297
 298 Footprint<br/>
 299
 300 Via<br/>
 301
 302 SubCircut<br/>
 303
 304 Other<br/>
 305
 306 </code>
 307 </p>
 308
 309 </div>
 310 <!-- EDIT1515 SECTION "Composite objects" [4993-5443] -->
 311 <h3 class="sectionedit1516"><a name="via" id="via">Via</a></h3>
 312 <div class="level3">
 313
 314 <p>
 315 Via is a composite object of type &#039;via&#039;.
 316 </p>
 317
 318 <p>
 319 There is a copper object around the hole on each &#039;physical layer&#039; it intersects.
 320 </p>
 321
 322 <p>
 323 The hole is represented as an object on &#039;outline&#039; layer on each &#039;physical layer&#039; it intersects.
 324 </p>
 325
 326 </div>
 327 <!-- EDIT1516 SECTION "Via" [5444-5678] -->
 328 <h3 class="sectionedit1517"><a name="footprint" id="footprint">Footprint</a></h3>
 329 <div class="level3">
 330
 331 <p>
 332 Footprint is a composite object of type &#039;footprint&#039;.
 333 </p>
 334
 335 <p>
 336 It has attributes Name and Sourcefile.
 337 </p>
 338
 339 <p>
 340 Expected properties:
 341 </p>
 342 <ol>
 343 <li class="level1"><div class="li"> Footprint contains layers with predefined names: Conductive, Silkscreen, Paste, Mask, Countryard</div>
 344 </li>
 345 <li class="level1"><div class="li"> Footprint can contain more conductive layers, each grouped with Paste and Mask layers ← useful for 2 sides mounting connectors</div>
 346 </li>
 347 <li class="level1"><div class="li"> Any connected element on conductive layer can be marked as Pin/Pad</div>
 348 </li>
 349 <li class="level1"><div class="li"> Footprint can contain Outline layer</div>
 350 </li>
 351 </ol>
 352
 353 </div>
 354 <!-- EDIT1517 SECTION "Footprint" [5679-6158] -->
 355 <h2 class="sectionedit1518"><a name="named_attributes" id="named_attributes">Named attributes</a></h2>
 356 <div class="level2">
 357
 358 <p>
 359 This is just my personal “To look at” section. – Martin Kupec<br/>
 360
 361 Refdefs should be distinguishable from the rest of Silk
 362 so they can be put on different Silk Layer.
 363 </p>
 364
 365 </div>
 366 <!-- EDIT1518 SECTION "Named attributes" [6159-] --></body>
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