[Arm-netbook] EOMA68-A20 schematics review / comparison needed - simple task.. just needs eyes

Luke Kenneth Casson Leighton lkcl at lkcl.net
Sun Aug 14 23:14:07 BST 2016

ok i need to do a schematic / PCB upgrade to add an extra address line
to the current EOMA68-A20 PCB to be able to access 2GB of RAM instead
of the current limit of 1GB.  i've looked at the cost of the 2x DDR3
x16 RAM ICs and they're nuts: $9 **EACH** whereas 4x DDR3 x8 RAM ICs
are $3.95 giving a total of $12 for the 2GB RAM.

this is why the cubietruck has 4x DDR3 x8 whereas the cubieboard2 only
has 2x DDR3 x16.

to pull this off i therefore need to copy the cubietruck's schematics
and make them exactly the same.  so far i've spotted that there's an
extra address line marked "SCS1" to pin AA4 on the EOMA68-A20
schematics (Page 5), that's marked "SA15" on the Cubietruck schematics
(Page 1).

what *really* needs to be done with as many eyes on it as possible is
to just go over both schematics and play "spot the difference".

* Page 1 of the CT schematics needs to be compared to Page 5 of the
EOMA68-A20 ones
* Page 4 likewise needs to be compared to Page 10.


now, i'm designating this page for notes:


feel free to edit or if difficulties reply here and i'll add the
discrepancies for you.

thx all.


crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

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