Any high thruput embedded ethernet modules?

Question

I've been looking around at embedded ethernet interface modules, most seem to have a serial interface with a max bit rate of 115200 or

230400 so I can only move about 20kbytes/sec with them. Are there any with byte-wide interfaces and higher data rates? I have a project where I'd like to move a byte stream of 250k bytes per second reliably from a microcontroller to a windows app thru a lightly used lan.

In general, what are the practical speed limits of moving data streams between devices on 10base and 100base lans?

TIA, Dan

Richard · Accepted Answer

If you can handle the code and CPU overhead, why not add in an Ethernet chipset directly? Both the Realtek (10Mbps) and ASIX (10/100) support

8-bit or 16-bit I/O mode).

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is a great starting point for driver code and prototype boards.

The key to direct Ethernet support depends on the protocol you're using to transmit to the Windows PC. TCP is reliable, but very overhead intensive (RAM, CPU, code). UDP provides no guarantees, but can be done with essentially no RAM (all in the NIC buffer). UDP without checksums would be even faster, if you have other data integrity measures (or don't care).

For UDP, an NE2000 driver can probably be done in ~100 instructions, with most of that being NIC initialization. I've got an ASIX implemented on AVR that'll do 6000+ packets/sec easily (UDP w/o cksum), so the volume's definitely there for small chips.

On shared hubs, 60% of the bandwidth; on switches, 100%. There will be additional reductions if you use a protocol like TCP that requires round-trip acknowledgements and buffer tracking.

Cheers, Richard

Richard · Answer

Forgot the punch line...This is with an 8MHz clock and bit-banging the I/O bus signals, plusenough headroom for some real work to be done.

nospam · Answer

Take a look at All of their products will easilly do 1M bytes + of TCP payload.

Any high thruput embedded ethernet modules?

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