[HH] Raspberry Pi stuff: enclosure, Pi NAS, closed source not good for education

[Drew Van Zandt]

Lasers to make one layer deep micro vias is a standard technique.  I have
used it in board designs at least ten years ago, though it has gotten much
cheaper since then.

--Drew
On Oct 6, 2012 1:34 PM, "Tom Metro" <tmetro+hhacking at gmail.com> wrote:

> Thanks to Stephen Adler for filming and posting his Raspberry Pi
> Video/Tutorial:
> http://www.mail-archive.com/hardwarehacking@blu.org/msg00487.html
>
> (I haven't viewed it, but will take a look when/if I get a Raspberry Pi.)
>
>
> Here's a fairly introductory Raspberry Pi tutorial that end with how to
> use a Raspberry Pi as a NAS:
>
> http://www.techradar.com/news/computing/pc/raspberry-pi-tutorial-how-to-do-more-1095946
>
>
> adafruit is promoting a colorful new Pi enclosure that is made of a
> rainbow assortment of laser cut acrylic that stacks up and is sandwiched
> between a top and bottom layer of clear acrylic:
>
> http://www.adafruit.com/blog/2012/09/20/in-stock-pibow-enclosure-for-raspberry-pi-computers/
>
>
> Why One Person Thinks Raspberry Pi Is Unsuitable For Education
>
> http://hardware.slashdot.org/story/12/09/25/2056240/why-one-person-thinks-raspberry-pi-is-unsuitable-for-education?utm_source=rss1.0mainlinkanon&utm_medium=feed
>
> (Quoting Slashdot, which quotes the original article,
>
> http://whitequark.org/blog/2012/09/25/why-raspberry-pi-is-unsuitable-for-education/
> )
>
>   "Raspberry Pi was designed for education. As any popular product is
>   bound to, Raspberry Pi has been criticized a lot for things like lack
>   of a box, absence of supplied charger or even WiFi. Raspberry Pi has a
>   much more fundamental flaw, which directly conflicts with its original
>   goal: it is a black box tightly sealed with patents and protected by
>   corporations. It isn't even remotely an open platform."
>
> The "proprietary GPU blob needed to boot" is mentioned, which has
> been discussed here before. The article also touches on the ARM being
> patented, which I don't have a problem with. But it also says that
> documentation on the ARM architecture is not freely available, and that
> indeed could be a problem.
>
> It goes on to list some completely open source CPU cores, as well as
> pointing out other proprietary vendors, like Atmel, have freely shared
> their documentation without onerous licensing restrictions.
>
> The author recommends the more open Beagle Board or Samsung ODROID-X as
> a Raspberry Pi alternative. He also recommends the fully open hardware
> Milkymist One, but it costs $800 and thus isn't a practical alternative.
> I guess he wasn't aware of some of the other open hardware boards that
> are in the same league as the Pi and still fairly cheap.
>
> Rhombus Tech (http://rhombus-tech.net/), a company creating an open
> hardware platform, was mentioned in the Slashdot comments. (Not terribly
> unique. I posted about another Raspberry Pi-class device recently
> (OLinuXino-Micro) that was open.) The Rhombus Tech products will use a
> PCMCIA-like metal-enclosed card design, and their first model will use
> an Allwinner A10 CPU.
>
> The full article is worth a read.
>
> The Slashdot blurb also references:
>
> Raspberry Pi's Secret: 'Sell Out a Little to Sell a Lot'
>
> http://www.wired.com/opinion/2012/09/raspberry-pi-insider-exclusive-sellout-to-sell-out
>
>   ...if other manufacturers copied the design, our partners would lose
>   their investment, which was approaching several million dollars.
>
>   How could we enable hacking while preventing cloning? Holding back the
>   schematics altogether troubled us. Not being open would impede
>   people's ability to interface and hack the hardware - defeating the
>   very goals we had set out to accomplish with Raspberry Pi in the first
>   place.
>
>   So we decided to publish the schematics, but hold back the detailed
>   Bill of Materials (BOM) and physical PCB design or "Gerbers" for a
>   limited amount of time. After all, hardware is just one part of our
>   overall plans. The schematics alone don't provide enough information
>   to clone the Pi without expending considerable effort re-laying the
>   PCB and figuring out the exact part used in each location.
>
> Ummm...if Broadcom is one of the partners, and the product depends on
> the Broadcom SoC that in turn requires a proprietary software blob, it
> would seem they already had two hard to bypass barriers to cloning:
> Broadcom could refuse to sell the SoC, or it could shut down the clones
> for copyright violation. Was Broadcom not cooperative?
>
> Here's an interesting bit on the board fabrication:
>
>   ...we had 253 connections to bring out (the BGA escape) in an area
>   much smaller than the size of a dime. And while there are special
>   high-density interconnect (HDI) techniques for densely layered PCBs,
>   those would just reduce yield and increase processing steps not to
>   mention the costs. ... What if we could steal the idea of "blind micro
>   vias" from high-density interconnects, but apply it cheaply enough for
>   the Pi design?
>
>   Instead of going through all the PCB layers, we made human-hair sized
>   holes (micro vias) that go through only the first couple of layers
>   (blind) - saving just enough space on the other layers for wiring up
>   the other PCB components. At high volumes, these holes could be made
>   quickly and efficiently with a laser. And it only cost a few cents
>   extra. Making these tradeoffs resulted in a relatively simple
>   six-layer board that didn't compromise power distribution. And it
>   enabled manufacturing at scale.
>
> Seems like another good way to ward off clones, unless this technique is
> widely known.
>
>  -Tom
>
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