Re: Questions on Single Board Computers
On Monday 12 June 2006 13:15, Mark Allyn wrote:
> Nikolaus:
>
> Thanks for the suggestion.
>
> The DMX serial protocol that I am using uses a packet of 512 words
> that it sends out at once. There is no need for an address field
> as each packet sent out ever the line has all 512 words (8 bits each).
>
> This is done to eliminate the need of having address bits. Each light
> in a DMX system (which, by the way is used in most modern theatres
> and concerts; especially the big rock concerts) is programmed to
> use a particular byte of that 512 bytes.
>
> The one thing that I did not mention in my email is that I am
> hoping for a 512 KBPS bit stream on the line so that I can
> update the brightness of each LED at least 60 times per second.
> A 9600 baud line would be too slow.
>
> Looking at the RS485 hardware specs, they say that it can run
> up to 1 MBPS for the distances that I am looking at (up to about
> 2 meters for a piece of clothing). It also has a fan out limit
> (transmitter to receivers) of about 32. That is show stopper
> for me.
>
> Perhaps I can make 'repeaters'; a RS488 receiver connected to a
> RS488 transmitter on a small PCB. I was hoping to avoid this.
>
> Truly,
>
> Mark Allyn
Have you considered the Dallas One-Wire stuff?
David
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