EOMA68 Computing Devices

by EOMA68

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

View all updates May 18, 2020

Command Not Found

by Luke Kenneth Casson Leighton

After careful thought as to how to triage the issue behind the spectacular 100% failure of the run of 50 production boards (the ones which looked like the PCBs had been cut with a chainsaw), it turns out that Mike completely ignored that plan, and paid from his own pocket for higher quality single-panel PCBs.

By not doing what I had asked, it saved him money, but was also a risk on his part if these new PCBs turned out not to be functional. As it is Mike’s money (he offered to pay all costs for the failed PCBs), I did not want to say anything. However, if the boards did not work, we would end up with further delays and yet more investigation needing to be carried out. So, those 20 test PCBs were successfully completed a couple of weeks ago, and that just left testing to find out if they actually worked.

As I am now in a different country, with no lab equipment, it would have been pretty pointless to send me the PCBs for test, in Europe, only to find that they are not even recognised via USB as an MTP device for FEL booting using allwinner-tools fel-boot.

When I was in Taiwan, the shipping was neither costly, problematic, nor long (SF Express: three days, compared to four to six weeks start to finish for Europe). So, as to prevent delay, I asked Mike to first plug them into the secondhand laptop that my friend Adam kindly handed to him in Shenzhen, a year ago. The idea being that the boards showing up in lsusb is at the very least indicative that:

  • the AXP209 is producing stable power for at least 1.2 V and 3.3 V from the incoming 5.0 V supply
  • the 24 MHz crystal is stable
  • the OTG port USB differential pair, 5.0 V power, and OTG connector itself are fine
  • the A20 processor itself is fine

It’s such a simple thing to do and has a very high bang-per-buck, diagnosis-wise.

Mike therefore had to find the time to test the boards, having also a business trip in another city to attend to, he returned Monday. At 3:20 AM UK time I got an email from him with images above and below. He had the EOMA68-A20 card plugged into the laptop, had managed to run xterm, but had first typed isusb (i for igloo) and then 1susb (number one, not l), but not lsusb our actual desired command.

Variable-width fonts have a hell of a lot to answer for when it comes to commands. I know of very few people who can tell at a glance the difference between l, I, and 1. Yes those are all different - here they are again in a fixed-width font: l, I, and 1.

With Mike being active and in front of the machine 10,000 miles away, despite it being 3:25 AM, I scrambled to get a remote login over the VPN and backup ssh tunnel that I had set up on the laptop. It worked! (I always find this amazing, that it is possible to connect to inexpensive machines in a completely different country and do useful work).

And, right there in /var/log/syslog was evidence the card he’d plugged in had been detected on USB. Communicating asynchronously by email, we tried a second one and that worked too.

Hurrah. We have two working Cards, which used the exact same components from the production stock as were used before. That means it was either something that the new manager did, or, more likely, it was the chainsaw massacre. I suspect that the chainsaw cutting resulted in a short between two layers as the distance to the edge and copper had to be made very small (12 mil which is around 0.5 mm). The 24 MHz crystal, for example, is literally right on the edge of the PCB, with only a tiny amount of ground via protection.

Having passed these initial tests, it’s now worthwhile for Mike’s engineers to solder on the PCMCIA connector (you can see it missing from the photo), checking for solder bridges, and then sending the completed board to me here in the UK by FedEx, not DHL despite that being easier for Mike since FedEx does not have a presence in Shenzhen and instead use third-party agents. Still, FedEx is the better choice because they deliver and then invoice you a week later for customs duty. DHL will delay delivery until you have paid, often forcing you to go collect from the nearest depot, which could be 50 miles away. With the insanity gripping people at the moment, the less hassle the better. Ergo, FedEx.

The next phase, after I confirm that HDMI, SD/MMC, USB, and VGA are operational, will be to arrange a mini production run. We learned our lesson: it will be likely that we will do a QTY 100 production run, then, if that goes well, ramp up to the remaining 900.

One thing at a time. As as reminder to everyone who continues to ask, "when will this ship?" the answer is, as always, when all of the unknown and unknowable issues between now and shipping have been solved. Only when we have everything solved and have successfully gone through at least one shipping cycle can we give any kind of stable prediction for a given delivery. This is just how it goes, and your patience is so genuinely appreciated.

About the Author

Luke Kenneth Casson Leighton

 Planet Earth. Usually.


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Product Choices

$65

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.


$65

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.


$65

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.


$65

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.


$55

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.


$450

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.


$500

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.


$1,200

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.


$20

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.


$35

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.


$15

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.

Credits

EOMA68


Luke Kenneth Casson Leighton

Developer

Christopher Waid

Sponsor

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