Neil Whelchel wrote: > Hello, > I guess I should have been more specific when I was discussing the > topology about connecting to a WAN, or even a non-related internal > network. I had intended to imply that > the WAN/LAN and the module network would be separate, one network card for > each. However, with a proper VLAN switch, I feel that it MAY be possible > to combine them, but I am not going to spend any time on that. ;) > I have looked into a few realtime Ethernet papers and implementations such > as Rtnet, Rether, and MicroNet, and it appears that Rtnet has most of > what is needed for the host side (if not work just fine as-is). However > for the I/O module side, the Ethernet stacks by Atmel and the like are > nearly useless to me because they are targeted > for much more complex (expensive) microcontrollers. (The compiled > Atmel stack is nearly 3 times the size of the total flash of the > microcontroller I am considering using.) Call me cheap, you'd be > right, but why throw all of the complexity and money at it when it is > likely that the cheaper, simpler approach is likely to provide the best > answer. NXP has some nice looking chips on paper, but they are full of bugs and holding off on some of the more desirable models. They would go for about $13 is small quantity. I gave up on them and started looking at Atmel, theirs apparently work and are in the same price range. The ARM7 derivatives in 100-pin TQFPs look about right for my use in this project. I would basically be moving a parallel port out to the ethernet, and the micro would readout a bunch of registers, assemble the data into a packet and ship it to the PC. The PC would run the PID code, etc. and then send back a packet to be disassembled and written to the device registers. If this was running on a 100 Mbit ethernet, it would be desirable to have a pretty fast CPU there, no 8051 derivatives.
Anyway, I put this aside as there are now parallel port plug-in cards with PCI-E. There will be a lot of overhead doing what we do to a parallel port over the PCI-E protocol, but then that is happening at gigabit/s speeds, so let the hardware do what it was designed to do. I need to get a computer with PCI-E so I can actually try this out and verify it works. Anyway, that's where I am right now. If somebody plows this (Ethernet) field for me, however, and it isn't proprietary, I might be able to do an interface for my boards using some similar technology. Jon ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
