[Open-graphics] Re: inexpensive project vga card batch?
James Richard Tyrer
tyrerj at acm.org
Sun Mar 9 16:29:51 EDT 2008
Dieter wrote:
>> No. 2 layers, one copper, one conductive silver ink 40 milliohms per square.
>> Usually you can identify traces that can stand some resistance, then make those be silver ink jumpers.
>>
>> UV cure acrylic "paint" is put down as insulator material, then ink over that
>> makes a 2-layer topology on one side additively and with no hole drilling, and ends up cheap and good.
>>
>> Voltage planes, if desired, need to be added as a separate board adhered on/soldered on.
>> For a pure SMT board zone, a ground plane can be copper adhesive tape and some soldering
>> to connect well, but breaks in it because tape is thinner than a board would not work well
>> unless butted together neatly and soldered over -- if pressure-adhesive copper will stay put for that...
>
> This sounds like it might be useful for DIY and for prototypes.
> But is it good enough for a serious high quality product? How is
> the long term reliability? Signal integrity?
>
> Is anyone using this for real products? If it is less expensive
> and "good enough", someone is bound to be using it.
>
>> PS the same thing could be done for OGD1, except the layout is so
>> much, probably needs 6 weeks and a prototype test and bugfix run
>> of 3 boards,
>
> I think the lion's share of the cost in OGD1 is the large FPGAs.
Still wonder where this is going.
Is the objective to produce a board to be used? or to produce an open
core for VGA.
NOTE: all commercially available graphics chips (including many
NorthBridge chips) intended for IBM compatible PCs use have a VGA core.
These are proprietary IP but they are open in the sense that they must
conform to the IBM VGA standard and the VESA extensions or they would be
useless.
I can find only one commercial IP VGA core available for licensing.
ATI/AMD still sells Rage XL chips so an application needing VGA/VESA for
basic graphics could use a commercial chip. IIUC, the Rage chip is
fully documented.
It would be best if our board had full VGA/VESA compatibility. So, a
working open VGA core would be helpful for our project except that it
might require an even larger FPGA or an additional FPGA.
--
JRT
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