[Noisebridge-discuss] Big LED Screen - potential upgrade?

[d p chang]

nils at shkoo.com writes:

> On Fri, 10 Apr 2009, d p chang wrote:
>>> nils at shkoo.com writes:
>>>> If you're interested in more of the technical details you can check
>>>> out the wiki page:
>>>>
>>>> https://www.noisebridge.net/wiki/Big_LED_Screen
>>
>> reading this, the panel almost looks like an 'isa smart panel' that some
>> lcd controlers do (or the last lcd controller i was involved w/).
>
> I think I'd charactarize it as very far from smart. :)  

:-)

the wiki made it seem that there was something downstream of the shift
registers that you're not using. this got me into the mode of thinking
of the whole shebang as 'controller'.

anyway, i was only mentioning that it looked somewhat like a 'standard'
for cheap lcd panels because you could get some parallelism out of
something that knew how to talk 'cheap lcd'. on the flip side, it is
somewhat painful to get the 'protocol' specs out of some manufacturers
even when you're buying their parts so i'm not sure if it was just the
parts i've looked at that talk this protocol.

>> w/ your dma idea, are you thinking of building a controller in front of
>> the existing controller or replacing the shift register stuff completely?
>
> It would be a lot of work to replace the shift register stuff

yeah, but 'simpler' on the control side for dma :-). 

something still has to the toggling of the shift registers, the work is
moving from the initiator to the target. that's the only reason i was
wondering about what was going be the dma target.

> If you're asking as to whether I'd want to replace the boarduinos with
> an ARM, then yes.

gotcha. 

unless i missed something else in the pictures (thanks for that) two spi
on an arm isn't going to replace two boarduinos since you have to change
the spi chipselect for the halves. spi seems fast enough though
(although maybe not for nice refresh).

in another message on this thread:

> On Fri, 10 Apr 2009, Andy Isaacson wrote:
>> On Thu, Apr 09, 2009 at 09:49:14PM -0700, nils at shkoo.com wrote:
>>> Does anyone have any input relating to this stuff or ideas of good boards
>>> to use?  Does anyone want 99 of those sparkfun SAM9-L9260 boards so we can
>>> get the bulk discount? :)
>>
>> I think this is a cheaper way to get an AT91:
>>
>> http://www.opencircuits.com/Linuxstamp
>>
>> (haven't looked if its SPI ports are reasonably configured, though.)
>
> The at91rm9200 only has a single SPI port.  However, it does make the
> pins available.  And, as far as I can tell, the only thing the
> linuxstamp uses SPI for is the flash

one thing to look out for is that arm parts have a small number of boot
options and sd/mmc usually isn't one of them. i'm not sure which would
be easier to either of these boards: 're-route' spi after boot or attach
some other boot source (i2c or dfu or 8bit flash).

\p
---
If everybody is thinking alike, then somebody isn't thinking.
		--- George S. Patton, Jr.