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 -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
