FPGA interface to ethernet

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beetlejuice

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Hi everyone (my first post)

I've come to this forum in search of some knowledge.

I have an application where I have digital video data in a memory device attached to an FPGA. The capture of the video into the memory is already accomplished.

I now need to transfer that data into a PC that maybe upto 50 metres away. My video data is just over 1.3MBytes. I want to transfer that data into a PC via ethernet UDP. The network is a simple peer to peer network. There is just one PC, no routers, switches etc, and never will be. I need the simplest method to get the data from my SDRAM attached into the PC via a cat 5 cable.

Can anyone give me some pointers on how best to achieve this.

Thanks
Mike
 

Hi,

I've already done this king of transfert. I used an vendor MAC IP (Altera TSE) and I did construct UDP frame in hardware. The anoying thing is that UDP CRC is placed before payload in the Ethernet frame so you can't calculate it on the fly while you are sending data....

You also may have to implement ARP because you need to know the destination address of your frames (unless you want to hardcode it).

Franck.
 

At the same time, you don't need to calculate the UDP checksum unless you really want to. UDP for ipv4 allows you to ignore the checksum. (see wikipedia).

same for the mac address in this case -- you probably can use the broadcast MAC.

the IP checksum can be pre-calculated in many cases.
 

Thanks for your replies

I'm not interested in the Checksum. I'm transmitting a digital image 2 times a second. If I get some corruption once in a while I can live with that. Also I dont want to go to the extream of ARP. I would use broardcast. Its just the FPGA transmitting data to the PC on a single Cat6 - Nothing else.

I believe I'm going to need to use an Ethernet PHY chip to interface from to the FPGA. Is this correct?

I'll need 10/100 baseT speed. Do you have any suggestions for a basic PHY device?

Or is there a simpler way to do this ?
 

Yes you'll need a PHY.

We are using a DP83848 in most of our design.

Franck.
 
For prototyping, consider using an FPGA development board that includes an Ethernet PHY unless you're already very experienced with integrating FPGAs and Ethernet PHYs, and high speed electronics. Implementing a MAC isn't trivial. Licensing one isn't ludicrously expensive. There are also some modules and chips that incorporate an IP stack if you're happier with lower performance and easier integration.
 

Just updating this thread for the moment. I never got round to building this interface yet, since other things have taken presidence.
Thanks for all your comments
 

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