[SGVHAK] Pi and Space Shuttle

[nopbin at gmail.com]

On Wed, Oct 3, 2012 at 5:05 PM, Braddock Gaskill wrote:
>
> Did anyone go to the Pi demo at nullspace?
>

Yes.

Rob talked a little bit about the motivation behind the Raspberry Pi
project.  Rob is currently a grad student who is taking a hiatus this
term to tour and promote the Pi.  The Raspberry Pi Foundation has
achieved its success with no full-time or paid employees, though Rob
may become its first.

The RPI was created by a some Broadcom engineers who work with this
platform in their day jobs and who hope to spur a new generation to
become creators rather than just consumers.  The low cost is hoped to
allow for risk taking and exploration without undo concern about
breakage.  The Raspberry Pi platform is basically a cell phone less
keyboard, display and cellular modem.  The hackerspace mentality of
doing stuff because its cool is seen as the best way to inspire kids
to engage.  They are quite happy to see that the low cost platform is
seeding various commercial ventures.

The group had anticipated having shipped 10k units by this point in
time, whereas in fact they have shipped a half million units.  The
unexpectedly large demand meant they exhausted their chip supply and
had to deal with a 23 week lead time for new chips from TSMC.  They
now feel that they have a better handle on sustainable demand and do
not anticipate additional supply delays.  Production is being handled
by a UK company that approached the foundation and was able to be cost
competitive with production in China.

There is currently plenty of RPI stock in the US.  While only rev2
boards are currently in production, there is intentionally no way to
specify whether you will get a rev1 or rev2 board when you order.
Margins are so low they cannot discount the old product and cannot
afford to be stuck with rev1 boards so they will continue to ship
whichever board is on-hand.  (Aside:
http://en.wikipedia.org/wiki/Osborne_effect)  Distributors typical
sell the RPI at a $5 markup.  Distributors include Farnell, Allied
Electronics, Newark, Element14.  Not discussed, but the distributors
seem to be regionally focused.  Note that stock is not evenly
maintained across distributors.  Some distributors have stock while
others are out of stock.

Adafruit (https://www.adafruit.com/category/105) has an extensive line
of peripherals including GPS, temperature sensors, screens, etc.  All
(?) designs are available as opensource hardware.

The camera peripheral (5 megapixel) is going through final approval
(?) and is expected to be available by the end of the year for $25.

Currently available, the GertBoard is a RPI add-on offering motor
drivers, DAC, ADC, and additional I/O.  It is sold as a kit requiring
assembly (soldering) from Newark for $47.36.
(http://www.newark.com/element14/gertbom/gertboard-bare-pcb-w-components/dp/24W8739)
(Rob reported its cost at $40.)  I think (?) Rob said that
self-assembly is required because FCC part B approval is still
pending.

GertBoard features: (as summarized at
http://www.raspberrypi.org/phpBB3/viewtopic.php?f=42&t=15021)
- 12 I/O ports buffered through 74HC244 Each with an LED
- 3 Push buttons.
- MCP3002 : 2 channel 10 bit A/D converter
- MCP4802 : 2 channel 8 bit D/A converter
- ULN2803A : 6 open collector channels up to 50V ~80ma/channel
- ATmega328P : High Performance, Low Power Atmel®AVR® 8-Bit
Microcontroller (Arduino)
- L6203 : 48V 4A motor controller.
- 780xx 3V3 LDO

Between the Composite Video, HDMI and the digital interface, a wide
range of displays are supported including TTL, Nokia DSI displays,
laptop displays, kindle, cheap displays and old TV's that have
Composite Video .  [Do reading before purchasing a display, because
not all devices appear to be currently software supported yet.  GPU
information (needed for customizing DSI and CSI interfaces) is not
publicly available.]  Adafruit may offer a number of known-working
displays.

Audio over HDMI is supported.  Two-way HDMI communication (enabling
remote control) is also supported, but beware of cheap HDMI cables
that may not connect the reverse channel.

There are a number of OS distributions available (Raspian, Debian,
Arch, QT5...).  The reason for forking Debian to create Raspian is to
provide hardware accelerated floating point on ARMv6, a combination
not prebuilt by Debian.

Yes, the board runs hot, but that is the nature of the product.  No
additional active or passive cooling is required unless aggressively
(?) overclocking.  On-board temperature sensor is available for
monitoring.

The GPU instruction set and architecture is not publicly available.
(Note GPU is embedded on the same Broadcom device as the ARM.) Some
GPU capabilities are exposed via a binary blob in Linux.  However, X11
support is not currently provided though it will be as soon as the
foundation developers have time.  A number of GPU accelerated examples
are available running outside of X11.  (See /opt/vc/src in the Raspian
distro for some examples.)  [The exact boundaries of what is and is
not supported is remains muddy to me despite having cursorily read
some of the online discussion.]

There were a few other odds and ends, but hopefully this gives the flavor.

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