[Arm-netbook] Plug computer and FreedomBox-related devices

Post by Paul Boddie
Hello,
So I was browsing the FreedomBox mailing list when I saw a mention of a plug
http://lists.alioth.debian.org/pipermail/freedombox-discuss/2015-
September/006879.html
https://www.kickstarter.com/projects/1547898916/own-mailbox-the-first-100-
confidential-mailbox
https://www.own-mailbox.com/

looks great!

Post by Paul Boddie
So, it seems that the initiators of the campaign have made their own Allwinner
A13 board with 256MB RAM and Ethernet support. It is open hardware,
apparently, and the software is Free Software, not some kind of proprietary
"snake oil" that some privacy campaigns tend to foist on their supporters.

goooood.

Post by Paul Boddie
It is a bit odd that they've decided to go their own way with the hardware,
though.

well, if it's libre hardware then that's good, i hope!

Post by Paul Boddie
Anyway, back to EOMA-68, and a quick search produced a page on the plug
http://rhombus-tech.net/community_ideas/plug_computer/
It occurred to me that if only we had EOMA-68 boards out there, maybe people
wouldn't be so enthusiastic to go to the trouble of making new boards and
running the gauntlet of crowdfunding.

i knooooow :)

here's the thing though:

(1) i have to get the standard right for a 10-year-old and greater period
(2) i have to get CPU Cards (plural) designed, sponsored, and tested
(3) i have to prove that it is, indeed, simpler and lower-cost to
make carrier boards.

so that's what i'm doing.

to explain, first: this project has an absolute top priority of being
*right* (defined as "viable long-term") over being "rushed to
profitability".

second: it's no good having just the one CPU Card out there. people
won't comprehend the modularity concept if there is only the
additional cost of having a single processor available.

third: even i was unable to move the micro-desktop board (which is
only 4in x 4.5in) forward because i had designed it as a 4-layer PCB -
costs are around $400 for qty 5 4-layer prototype boards on a 3 week
turnaround by complete contrast, a 7-day turnaround for qty 5 2-layer
prototype (bare copper) boards with larger vias is around $40 for qty
2, and around $100 for qty 5.

so.... it's getting there, paul.

l.

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send larg

Christopher Havel

2015-09-15 17:22:24 UTC

[...] even i was unable to move the micro-desktop board (which is
only 4in x 4.5in) forward because i had designed it as a 4-layer PCB -
costs are around $400 for qty 5 4-layer prototype boards on a 3 week
turnaround by complete contrast, a 7-day turnaround for qty 5 2-layer
prototype (bare copper) boards with larger vias is around $40 for qty
2, and around $100 for qty 5.

Imbecile question: is it at all reasonably possible to redesign the
micro-desktop board to be a 2-layer board?

Hrvoje Lasic

2015-09-15 17:41:50 UTC

On Tue, Sep 15, 2015 at 1:18 PM, Luke Kenneth Casson Leighton <

Imbecile question: is it at all reasonably possible to redesign the
micro-desktop board to be a 2-layer board?

If board have high speed design it is very unlikely that you can do it
properly (because you have to be careful about routing to ground, you have
many lines that you have to match etc etc and when you have only 2 layers
it is difficult to keep it all correct). In theory maybe it could be
possible but it is a hell of a work and then you risk a lot that PCB will
not be good.

_______________________________________________
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook

Luke Kenneth Casson Leighton

2015-09-16 01:41:23 UTC

Post by Hrvoje Lasic

On Tue, Sep 15, 2015 at 1:18 PM, Luke Kenneth Casson Leighton

Imbecile question: is it at all reasonably possible to redesign the
micro-desktop board to be a 2-layer board?

If board have high speed design it is very unlikely that you can do it
properly (because you have to be careful about routing to ground, you have
many lines that you have to match etc etc and when you have only 2 layers it
is difficult to keep it all correct). In theory maybe it could be possible
but it is a hell of a work and then you risk a lot that PCB will not be
good.

i took a look at a gigabit ethernet board that phil kindly sent me a
while back. the layout of the differential pairs was absolutely
fascinating [and the board had, obviously, passed FCC tests].

the layout involved putting ground vias exactly... something like
20mil from the differential pairs, spaced out at exactly something
like... 100mil, right the way *both* sides. there were no components
permitted either side for some distance either. there were no vias in
the actual differential pairs, either.

there were twenty sets of differential pairs like this - all with
exactly the same very very clearly and meticulously laid out
arrangement, with the spacing between each differential pair also very
meticulously laid out.

so it can be done.

in the micro-desktop board, however, the actual distance that the USB
differential pairs has to travel is well under 1cm. i am arranging
the connectors *directly* in front of where the signals come out. i
have also deliberately arranged the EOMA68 interface so that the pairs
come out directly and do not require a via to "cross over" each other.

so it is much less of a concern than might otherwise normally be.
these aren't 10cm traces, where EM radiation would definitely be a
major concern, they're literally 1cm long, and i intend to surround
them with ground vias.

of slightly more concern is the VGA interface (RGB/TTL being converted
to analogue), which will be operating at around 75mhz (or so).
however that's not 480mhz, so i am not hugely concerned. i am again
getting in as many GND vias as can fit, and keeping the traces very
very short. the buffer ICs actually straddle the PCMCIA interface on
the other side of the board, so that the RGB/TTL signals can, with
vias, go left or right, routing as appropriate, maximum trace length
about... 3mm.

l.

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send large attachments to

Hrvoje Lasic

2015-09-16 04:28:28 UTC

Post by Hrvoje Lasic

On Tue, Sep 15, 2015 at 7:22 PM, Christopher Havel <

On Tue, Sep 15, 2015 at 1:18 PM, Luke Kenneth Casson Leighton

Imbecile question: is it at all reasonably possible to redesign the
micro-desktop board to be a 2-layer board?

If board have high speed design it is very unlikely that you can do it
properly (because you have to be careful about routing to ground, you

have

many lines that you have to match etc etc and when you have only 2

layers it

is difficult to keep it all correct). In theory maybe it could be

possible

but it is a hell of a work and then you risk a lot that PCB will not be
good.

i took a look at a gigabit ethernet board that phil kindly sent me a
while back. the layout of the differential pairs was absolutely
fascinating [and the board had, obviously, passed FCC tests].
the layout involved putting ground vias exactly... something like
20mil from the differential pairs, spaced out at exactly something
like... 100mil, right the way *both* sides. there were no components
permitted either side for some distance either. there were no vias in
the actual differential pairs, either.
there were twenty sets of differential pairs like this - all with
exactly the same very very clearly and meticulously laid out
arrangement, with the spacing between each differential pair also very
meticulously laid out.
so it can be done.
in the micro-desktop board, however, the actual distance that the USB
differential pairs has to travel is well under 1cm. i am arranging
the connectors *directly* in front of where the signals come out. i
have also deliberately arranged the EOMA68 interface so that the pairs
come out directly and do not require a via to "cross over" each other.
so it is much less of a concern than might otherwise normally be.
these aren't 10cm traces, where EM radiation would definitely be a
major concern, they're literally 1cm long, and i intend to surround
them with ground vias.
of slightly more concern is the VGA interface (RGB/TTL being converted
to analogue), which will be operating at around 75mhz (or so).
however that's not 480mhz, so i am not hugely concerned. i am again
getting in as many GND vias as can fit, and keeping the traces very
very short. the buffer ICs actually straddle the PCMCIA interface on
the other side of the board, so that the RGB/TTL signals can, with
vias, go left or right, routing as appropriate, maximum trace length
about... 3mm.

anyway, absolutely amazing work to fit it all like you described.

Post by Hrvoje Lasic
l.
_______________________________________________
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook

Luke Kenneth Casson Leighton

2015-09-16 10:20:21 UTC

Post by Hrvoje Lasic
anyway, absolutely amazing work to fit it all like you described.

the complexity of that kind of 2-layer layout was one (unspoken)
reason why i took off ethernet. yehh, we'll see what happens, neh? :)

l.

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send large at

Luke Kenneth Casson Leighton

2015-09-16 01:42:20 UTC

On Tue, Sep 15, 2015 at 6:22 PM, Christopher Havel

On Tue, Sep 15, 2015 at 1:18 PM, Luke Kenneth Casson Leighton

Imbecile question: is it at all reasonably possible to redesign the
micro-desktop board to be a 2-layer board?

yes, i've done it already. i do have to increase the via sizes from
10mil + a 20mil surround to 12mil + a 24mil surround to fit the rules
of a lower-cost PCB factory that i know of, but other than that, it's
done already.

l.

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send l

Paul Boddie

2015-09-16 22:49:59 UTC

Post by Paul Boddie
It occurred to me that if only we had EOMA-68 boards out there, maybe
people wouldn't be so enthusiastic to go to the trouble of making new
boards and running the gauntlet of crowdfunding.

i knooooow :)
(1) i have to get the standard right for a 10-year-old and greater period
(2) i have to get CPU Cards (plural) designed, sponsored, and tested
(3) i have to prove that it is, indeed, simpler and lower-cost to
make carrier boards.
so that's what i'm doing.
to explain, first: this project has an absolute top priority of being
*right* (defined as "viable long-term") over being "rushed to
profitability".

Sure, I understand that. But what worries me a little is that experience isn't
being gained to possibly refine the standard or develop for it. Of course, I'm
writing this with only a superficial knowledge of what has gone on in the
past, and it is possible that people have done things with previously-produced
hardware that has informed the effort.

Post by Luke Kenneth Casson Leighton
second: it's no good having just the one CPU Card out there. people
won't comprehend the modularity concept if there is only the
additional cost of having a single processor available.

I understand this, too. It's also useful to have different devices they can be
used in as well, and I worry that these won't come about without any cards
being available.

One thing in the back of my mind (and part of a long list of things that I
could consider doing) is helping to design such a device, and for that I
suppose I need to collect links to documentation that might help me get
started.

Post by Luke Kenneth Casson Leighton
third: even i was unable to move the micro-desktop board (which is
only 4in x 4.5in) forward because i had designed it as a 4-layer PCB -
costs are around $400 for qty 5 4-layer prototype boards on a 3 week
turnaround by complete contrast, a 7-day turnaround for qty 5 2-layer
prototype (bare copper) boards with larger vias is around $40 for qty
2, and around $100 for qty 5.
so.... it's getting there, paul.

Yes, prototyping gets expensive for advanced stuff, I suppose, and since we're
not part of the normal industrial operations that can do this efficiently (in
terms of costs and other things), we're at a disadvantage.

Still, I wonder what those of us reading this list might be able to do to move
the effort forward in our own way.

Paul

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send large a

Luke Kenneth Casson Leighton

2015-09-16 23:34:15 UTC

Sure, I understand that. But what worries me a little is that experience isn't
being gained to possibly refine the standard

paul, you misunderstand the concept of a simple long-term standard.
it goes from "being developed and refined" to "absolutely locked
irrevocably without fail absolute without fail absolute 100% in stone"
with no phase in between.

once there are any end-users out there, there *is* no "second
chance". that's *IT*. i cannot make that complex enough to be
understood and accepted.

the reasons why there are no second chances are clearly laid out in
the white paper i wrote.

so, the opportunity, if anyone wants to get involved with
"refinement" of the standard, that's what they've had over the past
four years, and now it's almost over. they can talk to me, they can
read the white paper (in which i describe the justification of the
interface selection), and they can try to argue for additions or
changes, but right now the window of opportinity to do that is
closing, as i am about to send off two CPU Cards with the latest
(last) revisions.

anyone beyond that point in about 10-14 days time, if they want
modifications to the standard, it had better come with a cheque for
$5,000 attached to it in order to repay both my clients for the
samples that will have been made by that time.

Post by Paul Boddie
or develop for it.

that's straightforward "critical mass", which comes once the
standard's finalised, first products out the door, etc. etc.

Post by Paul Boddie
Of course, I'm
writing this with only a superficial knowledge of what has gone on in the
past, and it is possible that people have done things with previously-produced
hardware that has informed the effort.

http://rhombus-tech.net/allwinner_a10/news/

that's a brief timeline for the a10 cpu card (which became the a20
cpu card). the standard has been revised about... i think it's three
times since then, maybe four.

first revision was to remove SATA and replace it with a 2nd USB2.
second revision was to add VREFTTL, add SD/MMC and UART, third (or
possibly still part of the 2nd) was to reduce 24-pin RGB/TTL to 18-pin
RGB/TTL and use the 4 spare lines for an SPI interface, also USB3 was
added at some point. PWM and an extra EINT were also added. the
fourth - and almost certainly final revision - has been very recent:
removal of Ethernet, upgrading to being able to do USB 3.1, as well as
add 2 more EINT lines and 3 more GPIOs.

those interfaces have all been very carefully considered, especially
when developing the ICubeCorp IC3128 CPU Card, where, due to its low
pincount and being a QFP, there's *literally* only 2 spare unused pins
left on the *entire* processor that don't go to the EOMA68 interface
or the SD/MMC boot card.

I understand this, too. It's also useful to have different devices they can be
used in as well, and I worry that these won't come about without any cards
being available.

that's why i'm doing more than one product - micro-desktop as well as
the laptop. i've actually designed around... 5 or 6 different
products, all at different stages. the tablet is "on hold" because of
lack of interest [and, because it's a complex and dense 4-layer board
it's going to be tough converting it to 2-layer]. the 15in laptop is
sponsored so that's ok. and the micro-desktop, what with the PCB now
being 2-layer, is actually low-cost enough for me to put together a
new revision on a very low budget.

irony is all these will probably hit all at the same time.

Post by Paul Boddie
One thing in the back of my mind (and part of a long list of things that I
could consider doing)

Post by Paul Boddie
is helping to design such a device, and for that I
suppose I need to collect links to documentation that might help me get
started.

honestly, finding the parts (ones that are affordable, not
end-of-life, or fell off the back of a lorry and i do mean that
literally, even though they had to have a bit of a push to fall
of....) and/or finding the contacts _willing_ to source the parts -
that's the hardest bit of the entire job of designing any board.

oh. that and, of course, being able to get hold of the damn datasheets.

one cool product that would be awesome to have would be a 3d printer
controller that took an EOMA68 CPU Card. in some ways this would be a
bodge-job of taking a libre-hardware-licensed PCB design, expanding
its size a bit and connecting 5V power and USB up to the on-board USB
interface of the Micro-Controller.

that way you would have the actual computer *on* the same board that
had the (usually unreliable) power line... the one that gets spiked
due to 50hz mains fluctuations and lack of proper earth loops
associated with USB cables,500 watt PSUs, and amateur-designed PCBs.

a second cool product would be a robotics platform / educational platform.

another would be to track down a suitable libre-toolchain FPGA and
make a CPU Card out of it. i heard that someone has actually managed
to reverse-engineer one of the commonly-available FPGAs, to the point
where the toolchain is stable. saw an article about it recently.
that _would_ be awesome.

that would be great.

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send large attachments to arm-***@files.phcomp.c

Luke Kenneth Casson Leighton

2015-09-17 01:13:23 UTC

On Thu, Sep 17, 2015 at 2:04 AM, Alexander Stephen Thomas Ross

Post by Luke Kenneth Casson Leighton
that's why i'm doing more than one product - micro-desktop as well as
the laptop. i've actually designed around... 5 or 6 different
products, all at different stages. the tablet is "on hold" because of
lack of interest [and, because it's a complex and dense 4-layer board
it's going to be tough converting it to 2-layer]. the 15in laptop is
sponsored so that's ok. and the micro-desktop, what with the PCB now
being 2-layer, is actually low-cost enough for me to put together a
new revision on a very low budget.

awww :( ive been looking forward to the tablet, in fact ive been holding
out the last 4 years cus i wanted my first tablet to be a eoma one :D.
i guess lack of interest means lack of funds given to help make it... :/
hmmm...

remember the "or" there - ooorrr i redesign it to be 2-layer, in
which case it's no longer $600 for 5 PCBs but is something like...
$100 for 5 PCBs. the only problem being, they'd be 1.5mm thick
prototype PCBs, not the 1.2mm that the casework is designed for.

but yea, i look forward so much to buying the eoma(-68) laptop, the eoma
micro-desktop, eoma tablet, heck and maybe even the eoma games console!
the eoma-68 collection! yum yum!

im interested in the games console and think its brilliant that theres a
team working on a eoma-68 one :D, but i dont play games to so much these
days...

well that's ok, because as you can see from the scenarios section of
the white paper, and from the whole eoma68 concept, it's rather
plainly obvious that "an eoma68 games console" is NOT just "a games
console".

i do love reading your posts luke. i find them a great read. I even
loled at the bit about the parts falling off the lorry :D

haha goood :)

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send large attachments to arm-netboo

Paul Boddie

2015-09-17 11:04:43 UTC

Post by Paul Boddie
Sure, I understand that. But what worries me a little is that experience
isn't being gained to possibly refine the standard

paul, you misunderstand the concept of a simple long-term standard.

Not really. What I meant by "refined" is actually this:

[...]

Post by Luke Kenneth Casson Leighton
first revision was to remove SATA and replace it with a 2nd USB2.
second revision was to add VREFTTL, add SD/MMC and UART, third (or
possibly still part of the 2nd) was to reduce 24-pin RGB/TTL to 18-pin
RGB/TTL and use the 4 spare lines for an SPI interface, also USB3 was
added at some point. PWM and an extra EINT were also added. the
removal of Ethernet, upgrading to being able to do USB 3.1, as well as
add 2 more EINT lines and 3 more GPIOs.
those interfaces have all been very carefully considered, especially
when developing the ICubeCorp IC3128 CPU Card, where, due to its low
pincount and being a QFP, there's *literally* only 2 spare unused pins
left on the *entire* processor that don't go to the EOMA68 interface
or the SD/MMC boot card.

All of this has happened before we get to the point where we call it a final
standard, but what worries me is that there may be an application that hasn't
yet been considered because the collective experience of trying to make
devices using it is not broad enough.

I must admit that this is coloured by my interests in "retrocomputing" where
one can look at products that were made and then consider how they might have
been improved, even by a small amount, in a way that might have made them a
lot more successful. At the time, you'd have some company or other designing
and manufacturing their products to a tight schedule (usually to hit the
market at the best time of year), but there would be limitations discovered by
the customers that would limit the competitive lifetime of the product.

In any case, from what you've written, I guess we'll find out for ourselves
soon enough about how successful the refinement process has been. Not that I
think that it hasn't been successful enough, however.

[...]

Post by Paul Boddie
Still, I wonder what those of us reading this list might be able to do to
move the effort forward in our own way.

that would be great.

Any suggestions? :-)

Paul

_______________________________________________
arm-netbook mailing list arm-***@lists.phcomp.co.uk
http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook
Send large attachments to arm-netb

Luke Kenneth Casson Leighton

2015-09-17 12:13:44 UTC

Post by Paul Boddie
Sure, I understand that. But what worries me a little is that experience
isn't being gained to possibly refine the standard

paul, you misunderstand the concept of a simple long-term standard.

[...]

well, as well as the section on the elinux.org web site analysing and
tracking half a dozen different standards and their limitations,
that's what the section on "interfaces" in the white paper is for, to
go through the past (several decades of computing), learn from it,
predict where it's going, track that for 4 years, adjust the tracking
to make sure it fits, then re-predict, re-confirm, re-track and then
at some point say "ok done".

it's precisely the knowledge of prior failed standards, paul, that's
kept me from going, like a drunken naive wannab computaa n00b "okaay
yeahh i wanna do a standurd now, let's put some inturfaciz in 4 fun,
make some lolli y not?" - translating that into english it reads
"create something then throw it out the door in under a year and hope
it works" *NO*.

i recommend reading the sections on the white paper covering the
standard's development and justification (so that i don't have to
repeat it here) because i go into some depth to justify each of the
decisions that are made, including analysing and demonstrating how
long they've each been around, and how long they are likely to stay
around.

Post by Paul Boddie
I must admit that this is coloured by my interests in "retrocomputing" where
one can look at products that were made and then consider how they might have
been improved, even by a small amount, in a way that might have made them a
lot more successful.

well then, you would enjoy the anecdotes that i included in the white
paper, which include some historical and hilarious examples of exactly
that.

Post by Paul Boddie
At the time, you'd have some company or other designing
and manufacturing their products to a tight schedule (usually to hit the
market at the best time of year), but there would be limitations discovered by
the customers that would limit the competitive lifetime of the product.

... or in the case of standards, not enough thought went into them,
so they cause utter confusion and mental melt-down in the minds of
adopters. i am not joking but the only decent standards which do not
cause such complete melt-down are COM-Express and PC-104. there's no
"optionalitis" in those standards (except COM-Express module sizes,
and that's ok).

.... https://en.wikipedia.org/wiki/PC/104#Potential_Compatibility_Issues
aaargh noooo, PC-104 is.... arg. of course, because it's based
around the IBM PC which of course needs 12v, 5v and 3.3v, it's all
gone tits-up thanks to some carrier boards not properly supplying all
the required voltages, so the CPU boards themselves provide converters
to compensate... .which of course fucks everything up because the
difference between the I/O levels is enough to draw current one way or
the other and burn out components.

this is *EXACTLY* why the Certification Mark is so damn important, so
as to be able to stomp from a Great Height on anyone not properly
following the EOMA68 standard.

Post by Paul Boddie
In any case, from what you've written, I guess we'll find out for ourselves
soon enough about how successful the refinement process has been. Not that I
think that it hasn't been successful enough, however.
[...]