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

[Tom Cubie]

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.

>
> 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.

>
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