[Arm-netbook] arm-netbook Digest, Vol 82, Issue 47

Luke Kenneth Casson Leighton lkcl at lkcl.net
Tue May 23 19:29:50 BST 2017

crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

On Tue, May 23, 2017 at 2:25 PM, Ismo Väänänen <ismo.vaananen at gmail.com> wrote:
>> Date: Sun, 21 May 2017 00:45:30 +0100
>> From: Luke Kenneth Casson Leighton <lkcl at lkcl.net>
>> To: Eco-Concscious Computing <arm-netbook at lists.phcomp.co.uk>
>> Subject: Re: [Arm-netbook] GR8 based EOMA68 card
>> Message-ID:
>> <CAPweEDywhR-LUBAZojgGr2Hn0WJijOuZayxvJBK4WDH7MuhRDw at mail.gmail.com>
>> Content-Type: text/plain; charset="UTF-8"
>> ismo, hi,
>> it was just too tempting to have an initial go at converting the
>> CHIP_PRO_v1 schematic and PCB into a version of an EOMA68-GR8 card,
>> deliberately cutting it down to the absolute basic minimum - after
>> only about 6 hours i'm pretty much done connecting everything
>> together, having cut/paste bits and pieces over:
>> http://hands.com/~lkcl/eoma/gr8/
>> those are exported from PADS into 9.0 ASCII format if you want to take a
>> look.
> Sweet, thanks. Just imported these to Altium.
> Actually noticed that the Allegro .brd import in to Altium needs Allegro
> installed to function.

 yes: it uses COM (or DLLs) from allegro.

 but that .ASC file i made available was not *in* allegro, it was PADS 9.0.

> The imported layout looks like this: https://i.imgur.com/uPmEsQb.png

 looks pretty good.

>> importing from ORCAD/Allegro doesn't half make a dog's dinner of
>> things... *sigh*...
> It so does. None of the component parameters for the passives carried over
> in the import.
> The component values imported as separate strings for the passives, at least
> the cases are OK.
> Of course, the mentioned cases don't exist. So that needs some additional
> work.

 the values in the *board* are not important because you will not be
generating the BOM from the *board*, you will be generating the BOM as
a report from the *schematic*.

>> anyway it's the *absolute* absolute bare minimum.  TV-out, gone,
>> HP/MIC, gone.  OTG, gone.  NAND, gone.  SDC2 is connected to a MicroSD
>> slot, SDC0 is connected to EOMA68.  SPI2 is connected to EOMA68 so in
>> theory could also be used as bootable media (factory-install purposes
>> only).  boot is basically from on-board MicroSD, that can be
>> over-ridden if people want to by using a Housing MicroSD card (if the
>> Housing *has* one).
> That's OK with me. More space to use for potential future expansion.

 ... which, can i recommend that you consider for a much later
revision, get a first one out the door?

> Ya 0402 is a lot more sane to deal with than 0201.

 i'm not even sure if mike's factory can handle 0201, it's pretty
ridiculously small.

>> (5) re-add the copper pours for the power outputs from the inductors
>> (to the AXP209).
> This and in general figure out the power stuff.

 there's actually not a lot to figure out as this is such a simple
board.  the main one to make sure you do as a big plane area (on the
power layer) is VCC-3V3.  make sure it's big enough and wide enough to
extend to all the VIAs but don't go overboard.  extend it only as
needed.  remember all the "usual" messing about with DDR power planes,
all that's gone because the DDR's *on-board* the actual processor.

>> (6) do a full review to check that the dog's dinner mess made by ORCAD
>> hasn't split some of the NETs.  PADs doesn't support multi-named nets.
>> i found one (and joined them) but there may be others.
>> (7) sync'd PADS schematic and PCB so that a proper NETLIST review could be
>> done.
> It's gona be FUN mating the CHIP Pro schematic files with that layout.
> Absolute joy.

 you don't have to make *any* schematic files because that's the
second file i uploaded.  you just import that and you're done.

>> remember that this *really is* the bare minimum - it'll be amazingly
>> an under $10 BOM.  also that if you _did_ want to add HP and/or TV-out
>> and/or MIC sockets, as well as OTG.... you can't: there's not enough
>> room on the connector, not and have MicroSD as well.  so you can do 3
>> out of 4 of those connectors but not all.
> I'll fully decide on this later on, USB+Video would allow for standalone
> use.
> And sort-of usable while standalone is aligned with the spirit of the EOMA68
> standard (or how I see it at least).

 no it isn't.  it's a possibility but in absolutely no way is a
requirement.  the only reason i did it for the A20 is because the A20
has 3 USB ports (one of them OTG) and can handle 2 separate and
distinct simultaneous video outputs.

>> also bear in mind that there's a couple of tabs on the Litkconn
>> casework that fit *just* either side of the MicroSD, whch make it damn
>> awkward to fit the MicroSD anywhere but directly in the middle of the
>> end of the Card.
> Where can I find datasheets, drawings or 3d models for the Litckonn cases?

 with that PCB and schematic i did for you, and using mike's factory,
you won't actually need them.  you can however find them amongst


> Can I buy a few sample units from somewhere for fiddling around?

 i introduced you to mike but you have not responded.  you need to
keep an eye on that.  when communicating with mike please keep
communication SIMPLE.  "hello mike please quote me for sending X
sample litkconn pcmcia cases and pcmcia connectors, please provide
bank details so i can wire you some money".  and "hello mike please
quote me for production of 10 sample PCBs including assembly, it is a
6-layer stack, FR4, 1.2mm, here are the gerbers and the BOM".

 if you need anything else from him please CONSULT ME FIRST.

>> also bear in mind that finding mid-mount 2.5in and 3.5in multi-pin
>> jacks is a complete bitch.  i *might* have one supplier (who speaks
>> chinese only) who *might* be able to help, there (Runde).
> I'm perfectly OK with deleting the sound input/output.
> Just a shame to leave the sound hardware unused when it exists.

 mid-mount connectors are pretty fragile, as they are cut-aways from
the PCB.  if you have several of them you risk weakening the PCB so
much that people destroy the Card through careless lack of attention
when inserting or removing sockets, or forgetting that the cable's

 we'll just have to see how things get on with the A20 Card but i do
expect it to be a problem, people tripping over cables and ripping out
the actual USB or MicroHDMI socket.

>> so - what ya wanna do?  do you want to take over this layout/schematic
>> from here and go with it?  if you leave it as-is it should be easy to
>> finish within a matter of 2-3 weeks, which means that it's potentially
>> possible to add to the upcoming (2nd) planned crowdfunding campaign...
>> or you could run your own.
> More or less regardless of crowdfunding or anything I'll continue doing work
> on my vision of what a GR8 based EOMA68 card would be.
> But my progress won't be fast as I'm working full time and doing the same
> stuff at home as I do at work is not attractive every single day.

 hehe i know that one.  you need something sufficiently different.

> A low cost alternative for low powered embedded applications might also be
> attractive to some folks and in general for testing and debugging housings.

 hum.... hum....  ok i need an extra campaign and it needs to start
pretty soon (within 2-3 months), with extra Cards and Housings in it,
to be launched *simultaneously* as the A20 Cards and Microdesktop
housings are shipping.

 if that does not fit in with your planned down-time-schedule, how
about this: how about i get that Card up-and-running ASAP, keep you
up-to-date, then you will have something that's more-or-less completed
to work from which has many more features, how about that?

> On an other note, replying to this list while it's in digest mode is a bit
> weird.

 ah - i wondered why the delay.

> I might have to change it from digest to the individual message style
> and hope that gmail is good enough at clumping the threads.

 it is.... but you'll need to keep an eye out for anything mentioning
"GR8" with specific regular searches.  and please make sure that you
prioritise communications from mike as "important" (star them).


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