On Wed, Jul 08, 2020 at 11:46:49AM +0100, Luke Kenneth Casson Leighton wrote:
On Tue, Jun 16, 2020 at 9:45 AM Pablo Rath pablo@parobalth.org wrote:
I have recieved an EOMA68-A20 2.7.4 preproduction computer card and the 1.7 micro desktop (MD) last week. Just for clarification these boards are nothing new and have been discussed on this mailing list. If some of you already have their preproduction boards ready, I would appreciate any help, hints and suggestions to help me getting started.
Altough I have some experience with handling arm-boards I am now afraid to do something **stupid** and break/fry the boards. After some digging in the list-archives I found this thread ([1]) where Richard and Luke discuss how to connect the bare computer card with the bare micro desktop. I have many questions:
- Connecting computer card and micro desktop:
I am aware of the photos attached to [2]. Does the mentioned video exist?
no.
Richard, did you send photos to Luke? (If yes, can I have them?) Luke, do you want me to send you photos too before apllying power?
yes that would be good. visually it is pretty obvious. just do *not* bend or waggle the Card as it's inserted (however you may find that the connector is soldered at a slight angle of 1 to 3 degrees).
from visual inspection from the top, the gap left and right should be equal. this should be logically fairly obvious.
Images can be found here (I could not upload them to the rhombus-tech wiki becaus a virus checker is not defined): https://www.parobalth.org/eoma68-a20/eoma68-A20_2-7-4_1.JPG https://www.parobalth.org/eoma68-a20/eoma68-A20_2-7-4_2.JPG https://www.parobalth.org/eoma68-a20/eoma68-A20_2-7-4_3.JPG https://www.parobalth.org/eoma68-a20/eoma68-A20_2-7-4_4.JPG
from visual inspection from the front, it should also be obvious if the card has been inserted where the top row of pins has gone into the bottom part of the connector or vice-versa.
Visual inspection from the front looks good to me but is difficult to photograph with good light and correct focus.
If You Can See Pins You Got It Wrong.
I can't see pins anymore.
also, once inserted, place the anti-static bag *in between* the Card and the MicroDesktop PCB.
Is this for anti-static purpose or to add a bit of stability? Do you fold your bag to fit the entire length of computer-card?
- PSU for micro desktop:
According to the mentioned thread ([1]): "5.5mm jack with a 2.1mm centre hole, middle is +ve (aka "pin positive")", "Anywhere between 7 and 21v is fine, minimum 1A, 1 5A is better"
So I searched for a DC PSU in my household and read Wikipedia where it is mentioned that OD 5.5 mm / ID 2.1 mm is common on guitar effect pedals but my multi guitar effect pedal PSU did not fit (ID too small). Finally I found a matching DC PSU from a low volatage guitar amp. It says O / P: DC 15V, 2A and a symbol (positive polarity): L. P. S.
- -(.- +
you're better off checking with a multimeter. it's pretty standard (pin positive) however there is no substitute for actually checking. i.e.: don't guess - check. hardware is unforgiving.
Bought a multimeter and checked. DC PSU is good to go.
Should we document this somewhere on rhombus-tech.net?
yes, good idea.
Will do it in next couple of days.
- SD-card ready / U-Boot
Tried to compile u-boot-sunxi [4] and make exits with "System not configured". So Luke, what did you use as config
it's on the wiki somewhere. it has been 5 years so i will be searching just as much as you would be.
Ok.
or has something changed over the years?
no.
- Git, notes and documentation
Finally I am wondering where to put my notes. A subpage on rhombus-tech seems like a good idea good to me
yes.
After a quick check it seems one can not create subpages from the online editor (only edit pages). Can I still send you an ssh-key to get a better access to the wiki?
and indicates a work in progress in contrast to the various wikis out there. Where do you want me to push my work in progress git branches if I manage to hack something useful together?
i never needed to make any modifications to any linux kernel or u-boot source code, so one has not been set up.
Ok. Thanks.
kind regards Pablo