[Arm-netbook] SHIPPING!: EOMA-68 Micro Engineering Boards

[luke.leighton]

On Tue, Aug 6, 2013 at 11:18 PM, Henrik Nordström
<henrik at henriknordstrom.net> wrote:
> tis 2013-08-06 klockan 21:34 +0100 skrev luke.leighton:
>
>>  ah... with TI buying up National Semi i'm _sure_ they should have an
>> RGB/TTL-to-VGA IC by now.
>
> Olimex solved VGA ouput on their A13 boards without any special ICs...
> the LCD controller used by Allwinner is sufficiently flexible in timings
> to drive VGA with just a simple DAC on the LCD TTL output.

 holy cow that's hilarious.  4-bit DAC with a simple buffer and 4
resistors, 3of (one each for R, G and B).


> https://github.com/OLIMEX/OLINUXINO/tree/master/HARDWARE/A13-OLinuXino

 wow that's a dense schematic page.

> is electrically possible to do this with EOMA-68 as well, but maybe not
> sane to expect EOMA68 CPU modules to be able to stretch LCD timings to
> be suitable for driving VGA output directly.

 ... i don't see why not!  here's someone else doing that same trick,
a resistor ladder (no buffers):
    http://www.linusakesson.net/hardware/beagleboard/vga.php

here's another one, ignore the bits except the D/A converters, this
uses all 8 bits rather than just 4:
    http://www.next.gr/uploads/f898g892498.png

l.