Xue Schematic Comment

Werner Almesberger werner at openmoko.org
Sat Nov 13 17:01:02 EST 2010

Andr?s Calder?n wrote:
> Xu? is ready for (exhaustive) revision. Our Colombian team will review the
> design, but community support will be invaluable.

I had a very quick look at it. It looks quite good, but a few
improvements would be nice to have before starting a real review:

- URLs of the data sheets of the various chips used in there

  I've written a little system for caching and accessing data sheets.
  It's called "data sheet viewer", abbreviated to "dsv". It lives in
  eda-tools/dsv, but it's more convenient if you link/copy it into
  /usr/local/bin/ or $HOME/bin

  It uses a file with URLs and short names for data sheets. One example
  of such a file is ben-wpan/BOOKSHELF

  Each entry has one name tag (N:) that identifies the data sheet, plus
  zero or more aliases (A:) that also identify it. In terms of use,
  they're currently equivalent. "dsv" uses the name tag to detect the
  beginning of an entry, so the name has to be first.

  The data sheet URL is specified in a D: tag. (Only one per entry. If
  there are more, only the last one is used. It must be a PDF.)


  N: at86rf230
  A: transceiver
  A: txrx
  A: atrf
  D: http://www.atmel.com/dyn/resources/prod_documents/doc5131.pdf

  To download the data sheets, go to the directory where you want to
  build the cache, e.g., the project's home directory, and run
  dsv setup BOOKSHELF

  Now a data sheet can be accessed with  dsv <name>  e.g.,
  dsv txrx

  dsv searches for caches from the current directory towards the root.
  So if you're in a subdirectory of the project, it will find "txrx"
  as well. If you're in a different project, it won't find it.
- a bit more complete component specs

  E.g., on DBG_PRG, FB1 and FB2 are unlabeled. On "Ethernet Phy", L1,
  L2, L3, have the same problem, same thing on "USB". Ditto for the
  resistor packs (RP*) on "FPGA Port 1 [...}" and all the resistors on
  "Snesor PSU".

- maybe fix some of the in/out label glitches

  E.g., on "Ethernet Phy", VDD2 on U1 connects to a weird-looking +3.3V.
  The same happens on GND. I think they work as expected, but they still
  look confusing.  There's more of the same on other sheets, e.g., "Non
  volatile memories".

- do the unused-looking connections on expantion.sch (right side) and
  NV_MEMORIES.sch (lower right quadrant) serve any purpose ?

  If they will be used later, maybe add a comment in the schematics.

- do you have a BOM ? ;-)

- do you like the order in which the sheets appear in the PDF ? If not,
  we can change that easily in schhist.

> GIT repository:
> http://projects.qi-hardware.com/index.php/p/xue/

By the way, for reviewing the footprints designed with fped, you can

cd xue/kicad/modules
../../../eda-tools/fpd2pdf/fpd2pdf -o all.pdf *.fpd
xpdf all.pdf

- Werner

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