[Arm-netbook] update to EOMA68 specification [was Re: 5" LCD resolution 800x480 working for EOMA but color problems may exist because of miswire]

[joem]

On Mon, 2013-11-11 at 12:43 +0800, Tom Cubie wrote:
> On Mon, Nov 11, 2013 at 12:19 AM, joem <joem at martindale-electric.co.uk> wrote:
> >
> > :this is not a miswire.  the specification has now changed to reflect
> > :what cannot now be changed.
> >
> >
> >>> 5" LCD resolution 800x480 working for EOMA.
> >>> Details here
> >>> http://www.gplsquared.com/eoma_boot/eoma_boot.html#eoma_with_5inch_lcd
> >>> These displays are about $16 from Aliexpress:
> >>> http://www.aliexpress.com/item/5inch-5-TFT-LCD-LCM-RGB-800-480-Display-TOUCH/474988848.html
> >>>
> >>> I still notice a problem with color - Red and Blue appear to be swapped.
> >>
> >>  ok.  the specification's going to have to change.  we cannot modify
> >> the CPU Card, so the spec has to be changed to match the card.  what a
> >> pain.
> >
> >
> > Hmmmppp...... The is another outstanding issue that needs resolving
> > before the next batch goes into production - this time to do with the RS232 RX line.
> > When connected, the entire board is able to power up through the RX line.
> > The cubieboard1,2 and iteaduino plus and EOMA-A20 boards all have same defect
> > because I assume all of them were designed and tested by the same engineering
> > team from Wits with no peer review input onto the process.
> 
> The cubieboard1,2 are not designed by wits. All the allwinner boards
> including wits are following the allwinner reference design.


Hmm.. MK802 also infected - so I guess everyone is infected.

I put up suggestion for UART-RX repair - EOMAs and boards where internal
3.3V is accessible:
http://www.gplsquared.com/eoma_boot/eoma_boot.html#uart_repair


Turl in freenode #linux-sunxi suggests olimex solve it with their later
boards.



> > If you are doing another batch, make sure the CPU board RX line doesn't
> > power up the entire board through that line. They need to put a serial resistor in series
> > or a FET pair to sufficiently isolate the RX line. The same note applies to anyone else
> > using designs that originated with Allwinner/Wits.
> 
> we also have the RX line powering the board problem on our rk3188
> board. we use this ttl to use cable
> http://store.r0ck.me/products/ttl-to-usb-serial-cable and found that
> the serial port of 3188 is damaged when plugging and unplugging the
> power quickly. Further investigation we found that the ttl to usb
> cable is 5V and the voltage on rx can be as high as 4V. No problem
> using this cable on A10/A20 but the voltage tolerance for 3188 is less
> since it's 28nm made.