Hi,

I am wanting to send some IO between two devices for use with industrial
control. Ethernet PHYs seem to be a good solutions as they offer isolate
etc. However I need signalling to be quite fast - say 24 bits every uSec.
Standard ethernet frames have a maximum rate of 148.8 K packets per second.

So I was wondering if I could just use ethernet PHYs and send an abbreviated
packet - say minimal interframe gap, minimal preamble, minimal data. Has
anyone tried such a thing? Are PHYs just a coding/scrambling engine, or do
they rely to some degree on the frame structure - I'm hoping that maybe all
I need to be able to do is provide the start/end delimiters (to sync
everything up) and from there I can pass down nibbles as I see fit such that
what goes in one MII interface comes out the other end.

Let me know if you have done anything or know any more about this.

I plan to throw a prototype together soon and try to get an FPGA to FPGA
link working over an ethernet like interface.

============================
Clayton Gumbrell
CamSensor Technologies Limited
NEW ZEALAND
============================

Hi, There is a project I did long ago where I send "packet" as short as 8 byte. as for IPG the phy should be able to handle 32BT as this is what the MAC need to be able to do, and you probably/might can go even lower tho' I never tried. one thing you need to remember is that you need to send the first byte as 55 hex as this will be than replaced by the trasmiting phy with JK symbol and on the recieve side will start the rxdv. you are also advised to use somesort of error detection and if crc is "too much" at the very least consider chksum/parity etc as bit error will happen from time to time even if very rarely. have a nice day Illan -----Original Message----- From: Clayton Gumbrell [mailto:clayton@camsensor.co.nz] Sent: Tuesday, October 12, 2004 7:03 PM To: ethmac@opencores.org Subject: [ethmac] Can I use an Ethernet PHY for non-ethernet frames? Hi, I am wanting to send some IO between two devices for use with industrial control. Ethernet PHYs seem to be a good solutions as they offer isolate etc. However I need signalling to be quite fast - say 24 bits every uSec. Standard ethernet frames have a maximum rate of 148.8 K packets per second. So I was wondering if I could just use ethernet PHYs and send an abbreviated packet - say minimal interframe gap, minimal preamble, minimal data. Has anyone tried such a thing? Are PHYs just a coding/scrambling engine, or do they rely to some degree on the frame structure - I'm hoping that maybe all I need to be able to do is provide the start/end delimiters (to sync everything up) and from there I can pass down nibbles as I see fit such that what goes in one MII interface comes out the other end. Let me know if you have done anything or know any more about this. I plan to throw a prototype together soon and try to get an FPGA to FPGA link working over an ethernet like interface. ============================ Clayton Gumbrell CamSensor Technologies Limited NEW ZEALAND ============================ _______________________________________________ http://www.opencores.org/mailman/listinfo/ethmac

Hi, There is a project I did long ago where I send "packet" as short as 8 byte. as for IPG the phy should be able to handle 32BT as this is what the MAC need to be able to do, and you probably/might can go even lower tho' I never tried. one thing you need to remember is that you need to send the first byte as 55 hex as this will be than replaced by the trasmiting phy with JK symbol and on the recieve side will start the rxdv. you are also advised to use somesort of error detection and if crc is "too much" at the very least consider chksum/parity etc as bit error will happen from time to time even if very rarely. have a nice day Illan -----Original Message----- From: Clayton Gumbrell [mailto:clayton@camsensor.co.nz] Sent: Tuesday, October 12, 2004 7:03 PM To: ethmac@opencores.org Subject: [ethmac] Can I use an Ethernet PHY for non-ethernet frames? Hi, I am wanting to send some IO between two devices for use with industrial control. Ethernet PHYs seem to be a good solutions as they offer isolate etc. However I need signalling to be quite fast - say 24 bits every uSec. Standard ethernet frames have a maximum rate of 148.8 K packets per second. So I was wondering if I could just use ethernet PHYs and send an abbreviated packet - say minimal interframe gap, minimal preamble, minimal data. Has anyone tried such a thing? Are PHYs just a coding/scrambling engine, or do they rely to some degree on the frame structure - I'm hoping that maybe all I need to be able to do is provide the start/end delimiters (to sync everything up) and from there I can pass down nibbles as I see fit such that what goes in one MII interface comes out the other end. Let me know if you have done anything or know any more about this. I plan to throw a prototype together soon and try to get an FPGA to FPGA link working over an ethernet like interface. ============================ Clayton Gumbrell CamSensor Technologies Limited NEW ZEALAND ============================ _______________________________________________ http://www.opencores.org/mailman/listinfo/ethmac