Pandora 2 with EOMA-68 CPU Card

[lkcl]

folks hi,

i've not posted too often here but the open nature and the active community of the openpandora means that i learned a great deal in taking forward the projects that i'm working on.   i've also held off from posting here until there's something a little more concrete.  background links below.

basically i'd like to invite the developers of the openpandora to consider creating an EOMA-68 compliant hand-held (there is a team in mexico who are creating something similar, with a much smaller form-factor: 5in).

the reason is quite straightforward: the majority of the development - the hard parts i.e. the CPU, NAND, RAM, Micro-HDMI, Micro-USB, Micro-SD, are basically done and will shortly be available as a credit-card-sized off-the-shelf *USER UPGRADEABLE* component.

I/O which includes keyboard, sound, a 2nd Micro-SD, a 2nd USB, camera, battery and LCD management can be done using a 100-pin STM32F; this can be done with a 4-layer PCB, an example of which can be made available once it is completed (or an earlier version provided which will need rework and some errors to be corrected). it's presently a 118 x 125mm PCB that could be made quite a bit smaller.

source code for the CPU and the Embedded Controller (the STM32F) will always be free software, and the Ingenic JZ4760 CPU Card, if used, would mean that the entire product would be FSF Hardware-Endorseable.

i leave it at that for discussion and consideration.

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

http://rhombus-tech.net/community_ideas/kde_tablet/news/

http://rhombus-tech.net/jz4760/news/

http://rhombus-tech.net/freescale/iMX6/news/

 

[slaeshjag]

While I'm all for a user upgradeable pandora using a plug-in module, the EOMA-68 form factor looks way way way too bulky for use in the pandora without cutting down on battery size or making the handheld thicker.

 

[ShleeDragon]

This stuff is interesting.... but it's way too niche for us

The CPU isn't good enough too.

 

[Binky]

The problem is that the current pandora only has one PCB, with the controls on one side and the SOC/stuff on the other.

Although I do really like the idea of a system-on-card, there simply isn't room in a pandora-shaped case

 

[slaeshjag]

Room can be made for one, but not much. We're talking a footprint like a normal-sized USB memory stick. Not enough for a EOMA-68 card.

 

[monstercameron]

This stuff is interesting.... but it's way too niche for us

The CPU isn't good enough too.

the a10 is pretty good and an opensource driver will be available soon, also the a20 is pin compatible so they may eventually replace the a10.

 

[lkcl]

This stuff is interesting.... but it's way too niche for us

The CPU isn't good enough too.

are you *sure* about that?   a dual-core 1.2ghz Cortex A7 isn't good enough?  a quad-core iMX6 isn't good enough??  and future CPUs aren't good enough??  that's the whole point of the exercise - that it's future-upgradeable [with no future design costs for the openpandora team]

l.

This stuff is interesting.... but it's way too niche for us

The CPU isn't good enough too.

the a10 is pretty good and an opensource driver will be available soon, also the a20 is pin compatible so they may eventually replace the a10.

exactly.  there are actually three CPU Cards being designed, one of which takes 2 different CPUs (allwinner A10 and allwinner A20) and another which takes four different pin-compatible CPUs (the full iMX6 range).

also i've got an enquiry outstanding to speak with intel about using their upcoming ValleyView.  the "leaked documents" last year show that it would be absolutely perfect.  we'll see how far that gets, eh?

 

[lkcl]

Room can be made for one, but not much. We're talking a footprint like a normal-sized USB memory stick. Not enough for a EOMA-68 card.

that's why i mentioned that team in mexico who are designing a 5in hand-held games console: it *can* be done.   the CPU Card is only 5mm high, and each of the three i've been working with is packed ultra-densely with components.  Amphenol's socket is 6mm in height; i did track down one that doesn't have an ejector assembly, which saves more space, including 1mm on the height.

take a look at the picture here:

   http://rhombus-tech.net/community_ideas/kde_tablet/news/

the current openpandora is, according to wikipedia: 140.29×83.48×29.25 mm (5.523×3.287×1.152 in)

 well... the PCB on the page above is 125 x 118!  so, you do the following:

 a) lose the extra MicroSD socket (top right)

  B) lose the extra Micro-USB socket (top right) which allows you

 c) lose the extra USB 2.0 Hub (top middle)

 d) cut the camera (bottom left corner, in blue) which allows you to

 e) cut 20 pins from the STM32F which allows you to

 f) use a 64-pin STM32F thus saving even more space

 g) expand the PCB width by 15mm thus allowing you

 h) move the PMIC (AXP209) from its current location (top row towards the right end) down to the bottom left corner and finally

 i) you put on one of those lovely, lovely little WIFI SIP modules that everyone loves to hate.

etc. etc.

that just leaves the height clearance.  let's have a look....

http://openpandora.info/wp-content/uploads/2009/10/SilkFront.jpg

 wow, that's... quite a depth!  mind you, it is a laptop, not a tablet.   ok, so there's a bit of wiggle-room here.  holding a ruler up against the screen, it looks like the top of MicroSD cards are 13mm from the bottom of the case.  sooo, the EOMA-68 card would be sitting on the PCB, that's 6mm (if you include some wiggle-room to get it in and out); case would be 1mm thick - that leaves 6mm clearance for a battery.

 so yes, it all sounds perfectly doable to me.

 

[ShleeDragon]

I think it's great that ARM SOCs have reached a point where even the cheap china clones are quad core.... but I also doubt that ED would consider using an allwinner if he's able to get something that isn't a clone with some kind of real support. I say this because I've only ever seen allwinner stuff in really bad Chinese devices.
 
If the allwinners are actually good... and these A10 to A20 being dropin replacements would work quickly/easily/cheaply..... that's actually kinda cool, but it's trivia if Weston/Notaz cannot get them to work for what we need..... any EE's got an opinion?

----

Secondly, this slot in motherboard IO thing is cool, but I also think it's completely overkill..... I think they would be much more interesting in something like this. 

Exynos 4412 Prime Quad Core CPU Module with 2GB of DDR2/usb hub -> http://www.hardkernel.com/renewal_2011/products/prdt_info.php?g_code=G135270682824

 

[lkcl]

ok, so here's some very quick hacked-up schematics and a PCB layout, based on the Flying Squirrel Tablet (for the KDE Plasma Team).  full schematics are available, as well as PDFs and a PNG of the layout for those people who don't have the PCB software:

http://hands.com/~lkcl/eoma/pandora2/

for convenience let's use the features of the forum - i'm a bit of a luddite normally, and prefer mailing lists...

ok, so, that's:

* PMIC (AXP209) in the bottom left corner

* Microphone, Touchscreen, LCD, Speaker/Headphones and Power connector all along the bottom row

* 100-pin STM32F to the left of the PCMCIA socket (middle-left)

* 4-port USB Hub (still needed) hard-left, just left-up of the STM32F

* Battery and Power LEDs in the top hard left corner

* room (just!!!!) to the left of the Battery connector for a WIFI SIP module.

i've removed the TI SN75LVDS83b, because it's possible to get up to 800x600 LCD panels that will do 24-pin RGB/TTL.  However if greater resolution than that is needed, it's pushing things a bit, but it should be doable.

PCB size is 5.3 x 3.3 in - a little bit deeper (by not much) than the original pandora, but the only reason for that is because i didn't want to spend too much time reorganising the groups of components on the bottom edge of the PCB.

so... it all looks perfectly doable to me.  with a little bit of careful thought it might even be possible to squeeze the MicroSD card back on.  and, also, as long as the height clearance of components underneath it are kept to below 1.5mm, it should also be possible to fit a half-length MiniPCIe socket in that top left corner, allowing people to pick their own standard off-the-shelf WIFI Card.

fitting the SIM socket on as well might be a bit of a challenge... althouuuughhhh... there *do* exist combined MicroSD+SIM sockets, i've heard those exist.  that would be neat because then it would be possible to put in a 3G WCDMA or UMTS half-length USB-based MiniPCIe card, such as the Telit HE910, Option GTM661W and so on.

l.

 

[lkcl]

I think it's great that ARM SOCs have reached a point where even the cheap china clones are quad core.... but I also doubt that ED would consider using an allwinner if he's able to get something that isn't a clone with some kind of real support. I say this because I've only ever seen allwinner stuff in really bad Chinese devices.

the A10 is actually extremely good value-for-money.   it's a 1ghz ARM Cortex A8, which can be pushed to 1.2ghz with no difficulties, and it's $7.50 in 100k quantities.  it has a 32-bit DDR3 RAM interface that can go up to 800mhz (1gbyte of 800mhz DDR3 RAM is only $4 in 10k volumes).

if you've seen really bad chinese devices, chances are that they're *not* using the A10, but the A10s or possibly the A13.  the A13 is to be avoided AT ALL COSTS, because it only has a 16-bit-wide data bus.  also, bear in mind that most chinese devices are GPL-violating, but the A10 was *designed* to be easy to hack.  it's unbrickable, and that was designed by allwinner that way so that inexperienced chinese OEMs couldn't possibly screw it up.

the other reason why we picked the A10 is because when i asked Allwinner for GPL compliance, they happened to be having a Board Meeting the following day, and the answer came back "sure, here you go".  which is absolutely fantastic.  on that basis, there is now a *huge* active free software community based around the A10, and also because of the work that i've been doing (including making schematics and PCB design files available) there are a ton of A10 board clones out there.  the most recent one is yet another SO-DIMM-style Computer-on-Module.

anyway, the A10 is getting somewhat long-in-the-tooth: it's only still attractive due to the very high bang-per-buck ratio.  allwinner have been incredibly smart to make the dual-core Cortex A7 pin-compatible A20.

moving towards the future, then, rhombus-tech will *only* pick processors where there is full GPL compliance.  as a free software developer i have zero tolerance for promoting copyright violating products: apart from anything it exposes our clients to massive liability.

about the samsung exynos processors: i love them.  however, samsung are very cagey about who they work with.  they make enough money: they don't need the likes of us.  and they *will* not work with chinese factories except for guaranteed volumes over 50,000 units.  so... tricky one that!  i am however working on getting access to the exynos 5 - bit of diplomacy needed there though.

all a long story

Welcome back lkcl, looking forwarad to seeing good news

 

[monstercameron]

another note about the a13 and why is should be avoided, no hdmi out.

 

[lkcl]

another note about the a13 and why is should be avoided, no hdmi out.

 yep.  although i'm told informally that the die itself does have HDMI out, they wanted to stay ultra-low cost ($5) and not compete with the A10.  putting on 25 more pins would have pushed them up to a larger QFP - bigger than the designers were comfortable with  but, the 16-bit data lines to the DDR RAM made sure the A13 would not compete with the A10, all on its own... because it's SHITE!   no comparison, duh...

 

[lkcl]

btw i'd like people to know that i'll be happy to continue doing the schematics and PCB design layout... if people express an interest in seeing this happen.  just as with the original openpandora, you help pick the design that you'd be happy to pay for, and i'll help make it happen.

 

[monstercameron]

did rhombus finish their design around the (I know) amd g-series apus?

 

[Binky]

Do they have anything comparable to the OMAP5 lined up?

2 x cortex M4

2 x cortex A14 @ 2GHz

 

[ShleeDragon]

From what I remember. the A7 series of ARM is used as a low powered low performance cores? It might be totally awesome compared to the current SOC, but shouldn't we should aim for a A15.

So we're paying an extra and getting a massive increase in performance? 

 

[slaeshjag]

Don't hang yourself up on CPU speed. The formfactor allows us to make our own card if theirs turns out inadequate.

The point is, We still need a PCB covering the entire unit. If the card is 5mm thick, it'll add 5 mm to the thickness if not more, there is no way of getting around that.

 

[lkcl]

did rhombus finish their design around the (I know) amd g-series apus?

naah - too big.  too much power.  i'm chasing intel for valleyview though.

Don't hang yourself up on CPU speed. The formfactor allows us to make our own card if theirs turns out inadequate.

now you're getting it

 

[monstercameron]

do you own the website? lkcl