EOMA68 Computing Devices

by EOMA68

An Earth-friendly way to easily upgrade and fix your own computer

View all updates Nov 18, 2016

Latest from Shenzhen

by Luke Kenneth Casson Leighton

Pre-production prototypes of the Microdesktop and EOMA68-A20 boards were initiated last month, samples were completed last week and tested. Short version: another pre-production run is needed.

It’s just one of those things, but the decision has to be made to do another pre-production set of prototypes for both the Microdesktop PCB and the EOMA68-A20 PCB, both for different reasons. The sequence of events went something like this:

  • Complete the PCB design for each (in Hong Kong)
  • Send them to Mike's factory for production
  • Arrive in Shenzhen, find Runde and Jihang Electronics
  • Find out that the Micro-USB connector and HDMI connector are hard to get...
  • ...but the PCBs are already done, and most components already assembled on them.
  • Testing takes place of both PCBs, only to find that the Microdesktop SD "Card Detect" GPIO isn't an EINT (external interrupt)

So a combination of classic mistakes, as well as finding out that the two key components (Micro-HDMI mid-mount and Micro-USB mid-mount), which took eighteen months to negotiate and find suppliers for from outside of China, have much better, much easier-to-get alternatives.

The good news is that the 2 GB RAM upgrade worked perfectly at 384mhz. This was a high-risk modification to the DDR3 RAM Layout, learning from the Cubietruck’s schematics how to support four DDR3 8-bit RAM ICs. It’s something that’s not documented by Allwinner! Some undocumented pins had to be used, in particular an extra address line (A15) had to be added, moving aside other tracks in what is an extremely complex layout with timing-critical track lengths, to make room for the extra line. I’ll be absolutely honest: I really really don’t like doing DDR3 RAM layout. It’s risky, it’s fantastically complex, and it requires some extremely comprehensive and thorough analysis. Luckily, the risk paid off, and we can go to production with 2 GB of RAM.

The other good news: the previously-selected mid-mount Micro-HDMI connector was a compromise as it was a "reverse" type. The "reverse" type is at a different height in the middle of the PCB from the other two components (Micro-USB and Micro-SD), meaning that aesthetically it was less than ideal. By being forced to use Runde’s non-reverse-type of mid-mount Micro-HDMI, the three connectors are all inline, resulting in better aesthetics as well as a stronger face-plate.

The mistake made on the Microdesktop v1.5 PCB was just one of those things. The initial schematics were done nearly three years ago: it’s literally taken this long to spot the mistake! It was only discovered through comprehensive testing of the SD card interface, switching off the use of the "Detect" GPIO and resorting to "polling" mode (a mode which the sunxi 3.4 kernel is capable of supporting). In "polling" mode, the 2nd SD card was detected perfectly at 1-bit, 2-bit and 4-bit modes. However when using the "Detect" GPIO, it failed to be detected. Only then was it noticed that the GPIO selected was not an EINT (external interrupt).

I do find it hilarious that as the designer of EOMA68 I can make these kinds of basic mistakes. It’s good that I do so, so that I can emphasise to other people - before they spend their money on PCB design - how critical it is to double-check these things!

The other thing is that we’re taking the opportunity to switch to Runde’s commonly-available USB-A connectors for the Microdesktop PCB. It’s almost identical to the TE part, but the "peg" holes are in different locations. I’ve simply added extra ones so that either connector could be used. They don’t have the VGA D-Sub themselves but have agreed to source one for us, given that we’re using them for supply of literally every single connector on every single PCB designed so far, they’re happy to do this. It’s quite funny that they have absolutely no English at all, and I can’t speak Mandarin. Mike’s kindly acting as translator.

I’m basically done here in Shenzen for this round: Mike will sort out the new revisions of both PCBs, and through ZhongweiSemi, I’ll be waiting for Nexell to do the PCB review (including Simulation) for the EOMA68-S5P6818. Whilst that’s all happening, I’m returning to Hong Kong tomorrow, and will be applying for another visa (business visa this time) - actually three visas, one for each of us in my family. The remaining luggage and family will then travel to Zhuhai, where we’ll get set up and settled in. By that time, Mike and ZhongweiSemi should respectively be ready, and it will be time to return to Shenzhen - a place I am really beginning to enjoy, although it is extremely weird and I will never be able to call it home. Knowing this makes me appreciate my time here even more.

Other bits and pieces:

  • I've seen an exceptionally tiny design by a customer of ZhongweiSemi, with a quad-core processor and a special (and very expensive) hybrid NAND+eMMC IC by Samsung that fits into less than 35 mm x 45 mm. It's a customer design so I can't have access to it, but I now know it's possible to do and I would like to move forward the plans to make an EOMA50 "smartphone" module. Yes, not EOMA68 - EOMA50.

EOMA68 is too big for smartphones. EOMA50 was designed in parallel with EOMA68, but was shelved pending finding suitable processors. Now that one’s been found, the plan is to do a hybrid phone.

  • I'm also on the lookout for components to make a hybrid 10" tablet/netbook (EOMA68 compliant). However, this will have its camera, speakers and microphone on a special "hinge" that turns the entire camera - and speakers - around, meaning that it only needs one camera, as well as allowing the entire unit to be detached (and to operate as a stand-alone unit) The whole speaker-camera-microphone unit will also have a 2" touchscreen, and its own battery.. and be removable, with its own processor (an Ingenic ultra-low-power one), its own storage and probably also including a MicroSD card slot. Basically it will run its own OS (a fully Libre one of course), and be its own separate product: it'll be an MP3 player, micro-video player, webcam, USB and BT audio player, USB and BT-based microphone. And it will just so happen to slot into the top of a tablet.
  • I've also been contacted by someone who would like to consider buying some of what is termed the "Mini Desktop" units. These are a hugely-expanded variant of the Microdesktop, with extra USB ports, on-board WIFI (USB), on-board Audio (USB) and so on. Funnily enough this is actually just taking the Laptop PCB1 and adapting it slightly.

However, none of these ideas will interfere with the immediate tasks of the next few weeks and months, unless someone happens to step forward with sufficient sponsorship funding in order for me to find and pay someone else to do the PCB and Casework designs, while I focus on sorting out this current crowd-funding campaign. We’ll see what happens.

About the Author

Luke Kenneth Casson Leighton

 Planet Earth. Usually.

$237,697 raised

of $150,000 goal

158% Funded! Order Below

Product Choices


Libre Tea Computer Card

An EOMA68-compatible computer card with an Allwinner A20 dual core processor, 2 GB of RAM, and 8 GB of NAND flash pre-installed with the Parabola GNU/Linux-libre operating system. We expect the Libre Tea Computer Card to receive the Free Software Foundation's Respects Your Freedom (RYF) certification before the first units ship.


Practically Perfect Computer Card

An EOMA68-compatible computer card with an Allwinner A20 dual core processor, 2 GB of RAM, and 8 GB of NAND flash pre-installed with the Debian GNU/Linux operating system.


Numero Uno Computer Card

An EOMA68-compatible computer card with an Allwinner A20 dual core processor, 2 GB of RAM, and 8 GB of NAND flash pre-installed with the Devuan GNU/Linux operating system.


Getting Ahead Computer Card

An EOMA68-compatible computer card with an Allwinner A20 dual core processor, 2 GB of RAM, and 8 GB of NAND flash pre-installed with the Fedora 24 GNU/Linux operating system.


Micro Desktop Housing for Computer Card

This is a Micro Desktop base unit and power supply unit with a beautiful laser-cut stack of 3mm plywood panels that creates an aesthetically attractive tiny base unit for your Computer Cards. Excludes Computer Card, keyboard, mouse and VGA monitor.


PIY Laptop Housing Kit for Computer Card

This Print-It-Yourself (PIY) kit includes all the parts, cabling and boards (main, power, and controller, assembled and tested), and battery, charger, keyboard, LCD, and CTP-LCD for trackpad that are needed to build a complete Libre Laptop once you 3D print the enclosure from the freely available GPLv3+ licensed plans. Excludes Computer Card.


PFY Laptop Housing Kit for Computer Card

This Printed-For-You (PFY) kit has everything needed to create a full EOMA68 Laptop, including a 3D printed set of casework parts, bamboo plywood panels, tested and assembled PCBs, cables, battery, charger, keyboard, LCD, and CTP-LCD for trackpad. Available in a variety of colors and materials. Excludes Computer Card.


Completely Assembled Laptop + Computer Card

A meticulously hand-assembled and fully-tested laptop. Includes your choice of EOMA68-A20 Computer Card and 3D-printed casework.


PCMCIA/EOMA68 Breakout Board

One PCMCIA/EOMA68 Breakout Board with one surface mount PCMCIA header, and tracks to some convenient 2.54-mm-spaced through-holes. Added by popular demand, for access, tinkering, development work, testing, etc.


Pass-through Card

A simple card that takes in HDMI and USB and passes them on. Turns a Laptop Housing into a portable, battery-powered dock for your smartphone, USB-HDMI dongle computer, and tablet, or a second screen, keyboard, and mouse for your existing laptop or desktop PC.


USB + HDMI Cable Set for Standalone Operation

Includes a Micro HDMI Type D cable and 3-way USB-OTG Host-Charger cable tested and known to work with EOMA68 Computer Cards. These are the cables you need to run a Computer Card as a standalone device without the need for a housing. Also useful with the Micro Desktop or Laptop Housing to add a second screen and extra USB port.



We make the modular, upgradable, Earth-friendly EOMA68 laptop.

Luke Kenneth Casson Leighton


Christopher Waid


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