PCI LVDS cards

What's ruling out plain old 100baseT Ethernet?

Please excuse my ignorance, but exactly how would that work? Would I have to talk TCP/IP? Or can I just open the "port" can read and write raw data (like I do with a serial port). Thanks!

-larry

Well, as the saying goes --- if you have to ask, you're most not in a state to do something useful with the answer.

Have to: no. But you could.

Depends on what OS you're talking about. "Ports" are a TCP/IP concept, mainly. You could use them, but may need to go below that.

Sorry, I have no idea what that means.

If the answer was useful I'm sure I could have done something with it.

I'd rather not. I'd rather keep this as simiple as communicating over a serial port on a RS-232 cable

do

The system I am buiding will be running On Time's RTOS-32 OS. I also have to build a host emulator that will talk to my system. For that I can use anything I want, and I was hoping to use Linux (but if I had to use Windows I would).

What about serial ports and parallel ports?

Again, I ask: how can I use ethernet for direct point to point communication between 2 computers?

ethernet does not need anything else than point to point...no switches or routers of whatever kind. but: the transition from point2point to a true network is "for free"...and this is exactely one of the strong points speaking *in favour* of ethernet/ip.

when it comes to the *protocol* to be used i would strongly recommend:

-ip

-on top of it: tcp or udp, depending on your detailed requirements

-also, think about using a true application protocol on top of tcp.

what using tcp/ip, delivery of data is guaranteed. this is not necessarily the case when using plain serial point2point. also: from my (subjective, of course) point of view the real hard stuff is designing a meaninful, stable application protocol...and this you have to do no matter if you work "serial" or "ip".

michael

For the hardware use a cross over cable.

For the software on the server computer create a socket and get it to listen to a port. The client then requests a connection to be made. The server accepts the connection. Then write all the data that you want. This link

Peter

This is a suboptimal idea as the common mode of LVDS is extremely small. Go for a 100MBit LAN.

Rene

That's rather unlikely to work. The speed gap between usual RS232 connections and 33 Mbit/s one necessitates some changes in handling. In particular, sending byte by byte becomes quite impractical.

Cross-over cable, and knowledge. If you couldn't guess the former on your own, you need to brush up a lot on the latter.

listen

server

link

you

Thanks much! This was very useful info.

-larry

What does this mean? What is the "common mode of LVDS"?

If I could I would. The customer is fixated on LVDS for some reason. I did find a LVDS PCI card - it's the CDa card from EDT:

-larry

Sorry. The common mode voltage range of LVDS is in the order of less than one volt. Meaning, the GND of the innvolved card require to be within less than 1 Volt. This means you have to take the chassis potential with a thicker cable.

Rene

Check out

TC

Thanks, the uppper end FPGAs do have these links as standard. But as said, it won't reach far and the common mode voltage is critical.

Rene

StarFabric uses 8b10b encoded data and ac-coupling (which addresses the common mode voltage concerns). It works at distances of about 40 feet with low cost CAT-5 cables.

Effective data throughput is about 1.6 Gbps bi-directionally. In other words, you can transmit and recieve > 1.6 Gbps (200 MBytes/sec) at the same time provided you have a fast enough PCI bus.

Obviously, a 32-bit 33 MHz PCI bus limits throughput (total of Tx + Rx) to a little over100 MBytes/sec (800 Mbps).

Tx = Transmit, and Rx = Receive

TC