Re: Questions on Single Board Computers
Try gumstix.com. You might have to add an expansion board or
two, but from the looks of your post, you appear capable of
doing that...
--- Mark Allyn <allyn@well.com> wrote:
>
> Hello:
>
> I need some help trying to select a single board computer
> for a project that I am engaged in.
>
> The single board computer will be driving an array of
> approximatley
> 400 to 500 tri-color LED's that will be sewn into a piece of
> clothing.
> Each tri color LED has emitters for red, blue, and green.
> These three
> colors are combined to form any other color.
>
> This means that I will have about 1200 to 1500 individual
> light
> levels to control in real time.
>
> Further, as this is a piece of clothing, it needs to run on a
> 12
> volt battery. I will not have access to the mains.
>
> I plan to use a serial packet transmission to get the
> brightness
> information to each LED. I am currently designing the receive
> (using
> verilog and most likely a Xilinx CPLD for the packet receive
> and
> pulse width modulation to perform the dimming (LED brightness
> control
> is said to be the best then done by pulse width modulation).
> That
> part of the project I see no problem. There is already a
> lighting
> control protocol, called DMX, for which I have already created
> verilog HDL for implementation.
>
> The areas that I need help in is finding and assembling a
> suitable
> main processor. First of all, I need some serial bus
> (something like
> RS485) that can have one transmitter driving about 100
> receivers. I
> know that RS485 is limited to 32 receivers. Can this be
> expanded? Is
> there another serial interface that can have a single
> transmitter drive
> up to 100 receivers? I am only concerned about one way; there
> is
> no feedback required from the receivers (lamps) back to the
> main processor. From the looks of things; I will need three or
> four such serial drivers on my main processor unit.
>
> Also, I am looking for a main processor unit (most likely as
> SMB) that
> can do the following things:
>
> Be able to drive up to 1500 individual light levels (0-255
> steps of
> brightness for each one) at a rate so that each one can be
> refreshed
> once every 60 seconds.
>
> Would have either a wireless or wired network port so that I
> can
> access it to program it and make changes to the software.
>
> It must run Linux; use open source tools and software; I don't
> want
> to have to to $X,000's for commerical software. Preferably, I
> would
> like to see it run/be programmed from Debian/Ubunto/Mepis or
> some
> other Debian derivitive.
>
> Either have, or can accomodate a module with an FPGA; at some
> point,
> I want to incorporate an Audio A/D and audio signal analysis.
> I would
> like to drive my display on music; both on amplitude and
> frequency
> spectral images.
>
> I have done some looking through Linuxdevices.com. I do see a
> wide
> variety of devices there, but I cant seem to find anything
> with
> multiple RS485 interfaces. Perhaps this is asking for a bit
> much
> and I will have to design a suitable I/O driver (again, using
> CPLD's
> or FPGA's.
>
> What I don't want are disk drives, fancy graphcis controlers,
> fancy
> audio drivers (I am doing a/d; not d/a and driving sound); CD
> drives;
> SATA / IDE ports; whatever. Many of the devices seem to come
> with these
> as a default. All I need would be something to drive a small
> (perhaps
> something like a 4" by 4" inch) touch screen.
>
> It seems to me that PC/104 is a standard for these SBC's. Is
> this the
> case? I also see something called EBX.
>
> Have any of you have undergone a project similar to this? Have
> any
> one of you been particularly happy/unhappy with any paticular
> vendor
> or device for a project similar in scope as this one?
>
> I am willing to spend up to $1000 for the main processor, if
> that
> is what it takes. I am a bit confused at the diversity of
> pricing.
> I see stuff from GAO Engineering, for example, that is priced
> around
> $1500 for something that does not look that much better than
> others
> I see for around $100 to $200.
>
> I am willing to do all of the programming myself (or look for
> other
> open source programming to use). If I need to come up with a
> daughtor
> board, I am willing to do the design myself provided I get
> open enough
> documentation on interfacing with the SBC.
>
> If this is not the currect forum for this kind of question,
> perhaps
> can someone please refer me to where I can go with these types
> of
> questions?
>
> Thank you all for your help.
>
> Respectfuly,
>
> Mark Allyn
> Portland, Oregon
>
>
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