[Arm-netbook] EOMA server standard

[Gordan Bobic]

On 10/26/2012 05:13 PM, luke.leighton wrote:
> On Fri, Oct 26, 2012 at 4:39 PM, Gordan Bobic<gordan at bobich.net>  wrote:
>
>> Hang on - 24 pins out of 68 are reserved for RGB?!
>
>   28.  leaving 40 for everything else, including 8 for GND and 5V.
> scarey, huh? :)
>
>> If there was ever a
>> good reason to use a composite video output - this is it.
>
> ah.  considered that, 18 months ago.  rejected it for 2 reasons.  3.
>
> a) composite video however isn't a lowest-common-denominator across a
> wide range of SoCs

So add a chip to do it, maybe?

> b) for a 5 to 7in tablet with a low-cost 800x480 LCD (or a 480x320 or
> even less), in the critical price-sensitive bracket, you'd need a
> converter IC from composite video over to the low-cost RGB/TTL 800x480
> LCDs.
>
> c) for the hi-res range, i don't believe that composite video can
> really cope with 2048x2048 at 30fps (OMAP3530) or even 1920x1080p60, can
> it?

Not 100% sure. VGA is 15-pins (5 wires), of which most aren't used, and 
that is good for up to at least 2048x1536.

Perhaps this may be of use:
http://en.wikipedia.org/wiki/Serial_digital_interface

> plus, i hate to think of the cost of ICs for conversion from
> composite video over to dual-channel LVDS.

On the scale of the educated guess of a retail price of an EOMA card, 
how much difference is this _really_ going to make, compared to how much 
it cripples the standard?

> so... no.
>
> plus, jammy buggers that we are, those 40^H^H32 remaining pins are
> *just* enough for USB3, 1000Eth, SATA and I2C, with 12 pins to spare!

Fair enough. But if you had those other 20-odd pins, you could perhaps 
avoid having to have multiple standards.

Gordan