[Arm-netbook] passthrough, a20 and rk3288 cards

[Luke Kenneth Casson Leighton]

ok so still waiting for the updates to go out from crowdsupply, brief
news in the meantime.

revision 2.7.2 pre-production test pcb run has been ordered, i will be
assembling those myself, here in taiwan, using my host's equipment.
btw i didn't hear from anyone about the offer to send out
pre-production cards.

i'm having fun with the rk3288 board: putting on 600-pin 0.6mm pitch
bga ICs is tricky but doable.  the first board i managed to get access
via USB, and learned that it is actually possible to initialise them
by uploading u-boot-spl over USB.  however the DDR3 RAM would only
initialise if the clockrate was limited to 200mhz.  the second board i
tried, unfortunately the 3.3v power output was shorted to the DDR3 RAM
1.5v line and destroyed $20 worth of RAM ICs and a $20 processor.  not
doing that again.  the third board i am currently trying, i have to
get the ACT8846 properly soldered down: it's not initialising (yet) so
all outputs measure 0v.

the passthrough card i am still waiting for an adapter cable in order
to be able to wire a 2.4.1 revision a20 card's HDMI output to the
passthrough card's HDMI input.  it has to be micro-hdmi to micro-hdmi
hence why an adapter had to be ordered.

l.

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