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

[Henrik Nordström]

ons 2013-08-07 klockan 00:16 +0100 skrev luke.leighton:

>  wow that's a dense schematic page.

Yes they try to keep all their designs on a single page so the free
version of the proprietary program they are using can be used to modify
the design. It's all Open Hardware designs, so one important aspect for
them is that it should be easy for others to reuse their designs.

> > 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

Resistor ladder is fine for hobby use, but have some serious colour
issues in general use, having a hard time showing the same colour on
different monitors.

> 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

Right.. the Olimex design is really using a 8 buffer driving a resistor
ladder per colour. The buffers are split in 2x4bit in the schematics
simply because these buffers are 2x4bit buffers with separate output
control. The colour depth is limited to 6 bits per colour as that is
what the A13 provides.

Regards
Henrik