high speed comm

Nov 01, 2005 3 Replies

I am developing an embedded app that must receive a 128 byte message every 100 microseconds. It must reply with a 128 byte message within 100 us of receiving it's message (i.e. before the next message comes in). So I need bandwidth of 10,240,000 bits/second.



Does anyone know of any PCI cards that can support these speeds?



I have tried to do this with TCP/IP over ethernet, but was unable to maintain the needed speeds. I've also tried UDP, also without success. I've looked at some USB host-host devices, but I haven't found any that support these speeds and allow me to programmatically control them. Firewire isn't supported by my RTOS, so that's out. So now I'm thinking LVDS or some other high speed serial device, but I'm not having any luck finding applicable products. Anyone??



TIA!



-larry



It's actually worse than that. Given 10BaseT there's a 9.6us preamble. Add 20 bytes for overhead with a type 0600 ethernet packet, and you're up to 128us. Unless there's some terrible overhead I'm not aware of, 100BaseT should work.

Of course, it's game over if there's collisions, routers or switches....

The response time is a bit on the short side for a PC. A modern standard OS won't be able to cope with that.

An embedded systems however can.

Rene

Ing.Buero R.Tschaggelar - http://www.ibrtses.com & commercial newsgroups - http://www.talkto.net

brainbox.com have some running 15M and 18M

Med venlig hilsen/mojn/regards Martin Hansen Center for Software Innovation Stenager 2, DK-6400 Sønderborg, Web: www.cfsi.dk

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