Buck board layout peer review

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A Python Error Occurred:

Error on line 2 of Python tag (line 3 of source):
    buckboard_kerbs = str(BUCKBOARD_REVIEWS[cs_username])[1:-1]

KeyError: 'None'

Learning objectives

In ex03 we did the PCB layout of the buck converter circuit.

Now it is time to check the layout so we can find any issues before sending the boards out for fabrication. So every student is going to review 3 other students' designs. This does two things:

  • You'll get to see how other students do their designs, which might inspire or influence you.
  • You'll decrease the likelihood that your design is not functional.

Timelines

We have limited time for design reviews because we need to get on to layout.

Getting your peer designs

You'll be reviewing the layouts of the same people whose schematics you reviewed. You've been assigned the schematics of: <div><font color='red'><b>A Python Error Occurred:</b><p>

Error on line 1 of Python tag (line 21 of source):
    print('%s' % (buckboard_kerbs,))

NameError: name 'buckboard_kerbs' is not defined
<p></font></div>

  1. Pull the latest commits. Since you already cloned the repos when you did the schematic review, all you should need to do is to pull the latest changes, which should now include the pcb layout file. Open a terminal window. Navigate to the directory containing the repo and pull the latest changes:

git pull

You'll want to pull updates from all 3 different repos.

  1. Open the project. From the KiCad main window, hit File->Open Project, navigate to the repo and select the *.kicad_pro file.

It's possible we've assigned you to review a schematic from someone who has dropped the class. If so, please move on.

  1. Open the pcb. From the KiCad main window, you should now see the *.kicad_pcb and *.kicad_sch files. Double-click the pcb file to open it.

If that all works you should now see your peer's design.

Doing your review

Same as for the schematic, we're going to do the peer review as a markdown file. Markdown is a simple way of getting basic formatting in a text file. You can see the main commands here though many other guides also exist.

  1. Open up your favorite text editor.

  2. Create a blank markdown file in the main folder of the design you are reviewing. Name it None-layout-review.md. Save it.

  3. In your text editor, add two lines:

## Function

## Style

You're going to give feedback about the function of the design, aka does it work, and feedback about the style of the design, aka is it easy to read and understand.

Function

Here you're trying to figure out if there are any errors in the design that will prevent it from working.

Some checks to make (not an exhaustive list!):

  • The LM3671 is present and of the right footprint (5 pins, a SOT23-5 package, even though it might have a different name).
  • Rs, Cs, and LED have 0805 footprint.
  • One inductor, with a weird footprint (not 0805)
  • Nice fat traces everwhere including on the front-side, at least 30 mils wide but even wider where possible.
  • At least one M3 mounting hole, placed near the edge of the board.
  • Board size is 1.5" x 2"
  • 3 or 4 2x2 connectors with Connector_PinHeader_2.54mm:PinHeader_2x02_P2.54mm_Vertical footprint
  • Testpoints on VIN, 3V3, GND, maybe others
  • Testpoints are TestPoint:TestPoint_THTPad_2.0x2.0mm_Drill1.0mm footprint
  • Traces are not near edge of the board
  • Ground pour on the backside, and not overlying any backside traces
  • Run and pass the DRC

Note that this isn't a complete list. Use your judgement if you see any other issues!

If you find an error, add a line to the Function section, explaining the issue and being as specific as possible. For example:

## Function

* TP1 is wrong footprint
* Trace between LED and R1 is \<10 mils wide

## Style

If the design has no functional issues, write that:

## Function

* No issues

## Style

Style

Here you're trying to give feedback to make the design easier to understand for others, since one role of a schematic is to communicate with humans.

Some checks to make (not an exhaustive list!):

  • Text is left-to-right and up-to-down (or really just that it is "tasteful" and easy enough to read)
  • All components have designator on front silkscreen
  • Name and date or rev on silkscreen
  • Connectors have useful labels on silkscreen
  • TP are labeled with the signal they are testing
  • Text is not overlapping

If you find a style issue, add a line to the Style section, explaining the issue and being as specific as possible. For example:

## Function


## Style

* R1 and R2 are overlapping

If the design has no style issues, write that:

## Function


## Style

* No issues

Feedback doesn't necessarily need to be constructive. If the layout you are reviewing has no issues in a section, leave two points about aspects that are well done in their design pertaining to that section. Positive feedback is also valuable feedback!

Finish and submit your review

  1. When you're finished with your review, save your markdown file.

  2. Then stage, commit, and push the review.

Here we only want to stage your markdown file. Don't stage everything as you don't want to mess with your peer's design in case you made any inadvertent changes in KiCad.

git add None-layout-review.md

git commit -m 'peer review by [your kerberos]'

git push origin main

Close out of the layout file. If prompted, do not save any changes to the file.