>>>>> "Keith" == Keith Lofstrom <[email protected]> writes:
Keith> Looking at the specialized hardware inside a Skypilot at PLUG
Keith> Afters on Thursday, and the complexities associated with
Keith> getting a Linux distro on the single board computer in there,
Keith> does it make any sense at all to try to wedge an ALIX in a
Keith> Skypilot instead?
Not so much, and for the following reasons:
a) mounting the things is a problem. they are bulky, weigh about
20-25 lbs, and have some windloading possible. unless we can use
the mesh antennas, 95% of that bulk is a waste.
b) the primary advantage of these things to ptp is that they are $0,
so needing to invest more money in them kind of kills the advantage.
The two use-scenarios that make sense to me are:
1) use them intact, using stock SkyPilot firmware. The evaluation
of the feasability of this is incomplete, because we need a
SkyGateway before any of the SkyExtenders (what we have so far)
will even begin to talk to one another.
2) take them apart and use the pieces. there are two boards in the
thing, one is a custom SkyPilot board that is likely to be a lot
of work to do anything useful with. It manages the backhaul mesh
network and the antenna array (via an antenna selector board and
amplifier midway up the "nuclear core" looking section). *maybe*
we can figure out how to use that.
The other board is something SkyPilot just bought off the shelf
from a company called PePLink (their wireless stuff is marketed
as PePWave these days). This is the low-hanging fruit. Once
upon a time, PePLink was actively marketing these things
(MANGA/WINTI boards) for using in all sorts of third-party
devices (settop boxes, CPEs etc) and there is quite a bit of
information floating around about them.
It is based on a well-documented ARM922t-based cpu, the
Micrel/Kendin KS8695PI. It is running Linux now, there is Linux
support for the ethernet and other parts in the mainline kernel,
there is an SDK for building your own images for the board, etc.
Right now, there is one obstacle. The bootloader that it comes
with is very strange and (perhaps due to SkyPilot customizations)
does not load images built with the PePLink SDK, failing with an
error like: "block 0 invalid". We could either: i) figure out
what the bootloader is looking for through strategic disassembly
and give it what it wants; or ii) just replace the bootloader
with something open-source and well-known like u-boot or redboot.
Turns out there is a u-boot supported device based on the same
CPU already, and it might just require some tweaks to support
the flash chips. Someone that was already familiar with u-boot
could probably get something running on it in an afternoon
(redboot maybe a little longer). So far, it has taken me a few
months of handwringing and not trying at all (due to other
priorities). I think I could do it in a few days to a week with
some persistence, even starting from near zero on bootloader
development.
If we can get that board working with something familiar and
useful, which I think is within our not-quite-closed grasp, then
we have 600+ single board computers with radios that could be
deployed almost-for-free all over town. With the other parts
from the SkyExtenders, all we would need extra is a new
enclosure, maybe an indoor and an outdoor one. They could be
used as indoor or outdoor access points, ends of point-to-point
links, cpe's, etc.
The SkyExtender parts include two standard off-the-shelf atheros
radios, one an SR2 (a 400 mW b/g), (usually) a lower-powered
a/b/g radio, u.fl to N and mmcx to N pigtails and 2.4 GHz omni
antennas. The 5.8 GHz backhaul antennas could be reconnectorized
and made into non-array'd simple sectors as well, with or
without reflectors. If commodity prices were higher, the
aluminum in the base would have some value too. I understand
that TechShop in Beaverton has some casting capability, we could
turn them into aluminum ingots for use in 3D milling projects.
If we could get something open-source and understandable working
on the PPC-based "main" board inside that could be cool bonus, but
the solution to that without a lot more help is pretty remote at
the moment.
Keith> If an interface PC board is needed, Galen might be able to
Keith> help.
Galen has provided *much* valuable advice already.
Keith> [...] Alternately, there appears to be more than one Skypilot
Keith> hardware type, yes? If there are a few oddball units that are
Keith> not worth the trouble to reverse engineer, the ALIX approach
Keith> might be best applied to those.
I have 12 of the SkyExtender devices. I have now disassembled 5 of
them and 4 of them are essentially identical the same. From the
labelling, it looks like 11 of the 12 are the same. The one oddball
is the one we took apart at PLUG. It had a newer version of the WINTI
board, a 2-ethernet v3.1 rather than the 1-ethernet v2.5 that the
other 4 have had. I doubt that they board is that much different,
probably just more of the ethernet ports exposed (The KS8695 part
includes 5-port ethernet). We think we are getting about 80 more in
the next few months. I probably ought to have Aaron Burt looking at
the one-ethernet version instead of the one he got at random.
If anyone is interested in working on the bounty-laden bootloader
problem, I have some boards on-the-loose now, so speak up.
One little btw aside here. On the board I got out of the first
disassembled SkyExtender there was one 20-pin surface mount "mystery
part", that had the top sanded off. It had a 32kHz oscillator
attached and some of the pins were tracable. Two more clues from
Thursday night: the 2-ethernet board did not populate those pads; and
on one of the 3 other newly extracted boards had not been sanded, so I
found the label: "PePLink PL-2302". PL-2302 sounded like the usb
device from Prolific, however the datasheet for that one implies
theirs is a 28-pin part, so that doesn't match up. Google came up
otherwise empty handed. Sounds like something custom and (if not
populated) maybe not essential. Anywho.
--
Russell Senior, President
[email protected]
--
The Personal Telco Project - http://www.personaltelco.net/
Donate to PTP: http://www.personaltelco.net/donate
Archives: http://news.gmane.org/gmane.network.wireless.portland.general/
Etiquette: http://www.personaltelco.net/index.cgi/MailingListEtiquette
List information: http://lists.personaltelco.net
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to
[email protected]
