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pcb:drc

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This page will serve to document the design rule checker. This is presently documented “as-is”.

For work tasks, see the LaunchPad blueprint.

DRC Violations

  • Line/arc/silk width is too thin
  • Pin/via annular ring too small
  • Pin/via drill size too small
  • Pad too thin
  • Silk lines in elements
  • No paste
  • Insufficient copper overlap
  • Insufficient copper spacing
  • Hole too close to line/pad/pin/via
  • Hole touches arc
  • Insufficient clearance inside polygon

Process

Presently, the violations are identified in find.c, and then appended to a list in the gtk hid. In the lesstif and batch hids, you get a pop-up window or a text prompt that describes the error.

Executing the DRC() action will wipe out the selected, found, and DRC flags on most objects, although, apparently not elements.

  1. Execute the DRC() action.
  2. Generate the “DRC doesn't catch everything” warning.
  3. Save layer state and turn on all layers.
  4. Clear the FOUNDFLAG, DRCFLAG, and SELECTEDFLAG on all objects. DRC uses these flags to find errors.
  5. InitConnectionLookup – This resets all of the lists that are used for building the connectivity map.
  6. For every element pin, pad, and via, execute DRCFind. DRCFind builds a connection list starting from the given pin/pad/via four times. See below for a more detailed description of that process (if I get around to writing it).
    1. Apply a global bloat of value “Shrink”, and build a connection list, with global drc set to false. This will set the DRCFLAG and SELECTEDFLAG on every object that is touching the given pin/pad/via.
    2. Apply a global bloat of value 0, and build a connection list with global “drc” set to true.

To Do List

DRC tests:

  • Go through the DRC code for different kinds of violations to check that all possible code paths are being tested
  • Generate graphical output for the DRC report
  • Generate LaTeX output for the DRC report (wishlist!)
  • Figure out what else uses the “ConnectionLookup” code and write tests so that we don't break anything else as we're reworking the DRC

DRC backend work:

  • Separate the DRC code from the “ConnectionLookup” code.
  • Get rid of the “drc”, “User”, and “AndDraw” parameters. (Still trying to figure out what the implications of this would be)
  • Factor all of the different DRC tests into separate functions so that they can be executed individually.
  • Have DRC functions operate on “DataType” objects so that you can selectively apply the DRC to, say, the objects in the buffer
  • Work through more of Peter C's work to see how much of it we should incorporate (home/cparker/peterc_drc, he has quite a bit of good stuff here, but I'd like to include it intelligently instead of just picking the commits.)

DRC interface:

  • Create a DRC panel in the preferences window that allows for adjusting settings (possibly with image descriptions of the violations) and running specific tests individually
  • Figure out what the lesstif HID requirements are for the DRC code (it works differently, presenting violation by violation)

DRC bugs:

  • Highlight both offending objects instead of just one^^^
  • Find more than one “insufficient overlap” or “insufficient gap” per pin/pad/via^^^
  • Check for duplicate DRC errors before appending a new one (can happen if more than one pin is connected to an object)
  • On MacOS the images in the DRC window of the GTK HID are garbled
pcb/drc.1537637002.txt.gz · Last modified: 2018/09/22 13:23 by cparker