EOMA68 crowdsupply campaign starting tomorrow, 28th june 2016

woo, lots going on   haven't stopped writing answers to questions since we launched yesterday.  feel free if you have any questions, ask away.

Hi Luke,

I wanted to see the schematics, and I see an a31 folder but no a20 folder, and a file called "EOMA68_A31.pdf" however it is dated 2013 and labelled Allwinner Technology Co Ltd.

Is that the correct PDF, or should I be looking at a different one?

it's probably in the A10 folder.... the CPU Card itself isn't the thing you need to be looking at though (except out of curiosity or if you want to ignore the standard, which you can do), the *other side* though - where you'd want to make your own base boards, that's much more interesting.  hmmm... looking around news i'll need to take a look.

what is it exactly that you'd like to see?

Hi Luke,

I see a link that says:

• EOMA68-A20 Schematics and PDFs contains the complete set of datasheets for the EOMA68-A20 Computer Card

but it goes to a location where I can see many files, but not the A20 Computer Card or A10 folder.

I wanted to see the schematic to learn more about the product that will be supplied. Also I don't want to end up with a paperweight if the overall project ceases and any forums die one day, i.e. the schematics will allow me to continue to benefit from the Computer Card when there is no technical support. . The page states that it is available, but I can't find it. Is there a precise URL that I may be missing for the PDF schematics?

Just as an example I recently contributed to the Lime SDR funding campaign but I didn't do so until I had examined its schematics and then the main component datasheet and register examination, so I could see precisely what it featured for the sum of funds demanded. I was satisfied I would be able to make use of it and that it was worthwhile so I contributed accordingly.

cool, great!  ok i'll fire up the VM and generate a PDF, it's been so busy i've not had time to keep everything up-to-date, but the EOMA68-A20 CPU Card is the one exception where, to ensure that the investment is recovered and that manufacturing is not disrupted by third party suppliers, i'm *not* releasing the full schematics and PCB files... yet.  which is why you haven't been able to find them uploaded, there. a PDF of the schematics, not a problem.  give me a mo.  btw please bear in mind, this will be the one with four 8x DDR3 RAM ICs, and i'll be doing a redesign to use two 16x DDR3 ICs - it's a lower-cost layout.

okay!  so, i created an a20 directory http://hands.com/~lkcl/eoma/allwinner/a20 - the PDF schematic's there for review.  background: we had an extremely competent engineer (one of wits-tech's absolute best) put that together initially, and i've been maintaining it since, having taught myself how to do PCB CAD over the past four years.  some of the pages (page 1-4 for example) are a leetle out-of-date, but you get the general idea.  you can actually find schematic PDFs of various tablets around: they will look reaally similar, also if you compare to the cubieboard schematics they will look *really* similar

page 5 is DDR3 connectivity (and power) for the A20

page 6 is general A20 GPIO, JTAG, and other peripherals such as HDMI, NAND, SPI, SD/MMC etc.

page 7 is the AXP209 Power Management IC

page 8 is some of the SOT23-5 and SOT-23-6 discrete PMICs needed (1.5v, 3.3v, 2.5v)

page 9 is pull-ups, XTALs, all stuff that needs to right next to the A20

page 10 is the 4x DDR3 8-bit RAM ICs (to be replaced with 2x DDR3 16-bit)

page 11 is the NAND IC, Micro SD/MMC card connector and Micro-USB-OTG

page 12 is the HDMI connector PLEASE NOTE: the RTL8201 has been REMOVED

page 13 is the EOMA68 connector, bless 'im our engineer who made this didn't speak very good english, he left it as "LCD", i just haven't had time to rename it

basically it's incredibly similar to the cubieboard, just less busy because EOMA68 is a simple standard.  it should be clear though that the actual important stuff is the EOMA68 connector and the other connectors... *not* the actual processor, RAM or NAND.  you've looked at some of the other PDF files (for the A31 for example) so that should be clear: they're all the same EOMA68 connector.  the only exception to this would be if you needed to *NOT* conform to the EOMA68 standard.  for example, you noticed that one of the pins on the EOMA68 connector had some other multiplexed functionality by going over the A20 datasheet, and that was something that you specifically wanted to use, and were happy to be making your own baseboard that wasn't compliant with the EOMA68 specification.

why would that be beneficial?  well, the plan here is to ramp up to mass-volume, so that these end up being sold in best-buy, walmart, staples and other supermarkets, at really *really* competitive prices.  "just go buy an upgrade computer card" like you would say "just go buy a bigger memory card".

what *that* means is that as an engineer you could literally walk into a supermarket and buy their entire stock of computer cards to fulfil a tight customer deadline!  but not with something that has bits sticking out of it at least 12mm high: the component clearance on the EOMA68-A20 is only about 4mm.

anyway - hope that helps, i leave to you it.

Hi Luke,

Excellent, thanks. However I currently get a 'permission denied' message, I think the file or folder may need changed permissions:

Hi Luke,

Excellent, thanks. However I currently get a 'permission denied' message, I think the file or folder may need changed permissions:

doh! sorry  - sorted   used rsync to copy it up, it often sets permissions to rw-------.