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README.md
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README.md

Lab11 and Eagle

We've adopted some conventions and styles over the years. Some of these require a little more effort up front, but will pay off in the long run if you end up needing to scale up board production, or simply to make stuff that's easily usable by others in lab.

Starting a new board

Directory Structure

A bunch of scripts rely on this and it works well. Follow it.

<repo folder>/hardware/<board-name>/<rev-x>/board-name.sch
                        ^^^^^^^^^^          ^^^^^^^^^^
                        Note that these MUST be the same

Revisions

We use letters for revisions. So this should start with rev-a and increment appropriately. Once you ship a board for manufacture, that revision is set in stone. Do not modify it. Even if you only made two boards and they didn't work because of a silly bug, that revision will still stick around for all of time. Sometimes boards end up on revision e, g, i, whatever.

When you need to start a new revision, simply make a new folder (rev-b) and cp rev-a/board_name.sch rev-a/board-name.brd rev-b/. You should then commit this new revision, so that the base starting point for the new rev is exactly the old rev.

Schematic Setup and Attributes

Eagle has a metadata system called "Attributes", first, set up some global attributes for your new board. Go to the Edit menu then Global Attributes.

  1. The REV attribute should be set to A, B, C... depending on the revision
  2. The TITLE attribute should be set to the name of the board, in this case board-name
  3. The AUTHOR attribute should be set to the name of the creator of the board

Finishing the Schematic and Board

This overview is not going to go into how to design or layout PCBs.

We have some tips and conventions that we've established over time that are worth reading over:

There are some additional resources online that may be useful:

For PCB design which contain RF traces ( > 100 MHz), there are some general rules of thumb:

Design Review

Once you think you are done, it's a really good idea to have others in labe review your work. Recently, we've been creating an emphemeral slack channel for each board and tossing reviews there. It's been working pretty well.

If this is an earlier board for you (or even if you're experienced and this is your first Lab11 board), there will probably be a healthy amount of feedback. That's a good thing! Learn from it :)

Creating Gerbers

Once you are happy with the board you need to create gerber files you can send to a board house.

Creating a Bill of Materials (BOM)

Creating a BOM is crucial for future assembly, for you, for others in lab, and for professional assemblers. We've developed a number of conventions from experience over the years, follow them - if things change in the world, update them, but talk about it with older lab folk first.

Package Things Up (AKA, run the magic script)

Once you have done all the setup work, it's time to let scripts take over. These scripts will do several things:

  • Put all the gerbers in a zip.
    • This you can upload to the board house who will make the PCB.
  • Put all the gerbers and a couple addition files in a zip for the assembler.
    • This you can send to an assembler when getting a quote/boards assembled.
  • Create a documenting PDF.
    • This will but the schematic, pictures of all of the copper layers, a good graphic to use when assembling the board, and a copy of the bom into a PDF.
  • Convert the bom to txt and csv formats.
    • These are not as useful but are good for using grep.
  • Package everything into several a master zips.
    • board-name_REV_DATE.zip - an archive of everything, good for posting online or sharing with others
    • board-name_REV_to_fab_DATE.zip - files needed for PCB fabrication, good for uploading to board houses
    • board-name_REV_to_assembler_DATE.zip - files needed for assembly, good for upload to an assembly shop
    • board-name_REV_to_stencil_DATE.zip - files needed for stencil production, good for upload to a stencil producer

To run, simply invoke the meta-script:

github.com/lab11/eagle/scripts/eagle.py

in the same folder as the .brd and .sch files.

Viola!

Fabrication

Whoo! You've got a few options to pick from here, including different board houses and possibly assembly.