I found this attachment in my notes from last year's test. It was for a particularly bad pair of iBob and BEE2 FPGA #2 over a 3m copper link. It's not noted in the document, but I think that the thermistor was not getting the full temperature of the heat-sink - an IR gun measured that same heat sink at ~80+C a few days later. The fans reduced the temperature to ~ 40C.
Billy -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Matt Dexter Sent: Friday, April 03, 2009 6:55 PM To: G Jones Cc: [email protected] Subject: Re: [casper] iBOB to BEE2 XAUI cable length I haven't had time yet to fully document this so here is just a quick and dirty warning about using too many active CX4 links, such as the fiber optic ones from Zarlink, on 1 BEE2. We have these: Zarlink OFNR Riser cables : 10 meter p/n ZL60615MJDE Zarlink OFNP Plenum cables : 15 meter p/n ZL60615MJDF Each Zarlink FO transceiver, 2 per cable assembly, requires 3.3VDC input with typ/max of 0.3A/0.4A. This current requirement is an important parameter because even though the BEE2 has the circuitry to support active CX4 links at each of its 18 ports, it doesn't mean the BEE2 has the power supply capacity to support more thank a few active links at a time. Our application has mainly 2 cables, 2 transcievers in total, per BEE2 and found this to work AOK. We have 1 BEE2 w/ 3 transceiver and that seems to work as well but maybe hasn't been tested as well the others. I tested 4 Zarlink FO cable assemblies, 8 FO transceivers in total, and no copper CX4 cables the quicky test suite XAUI link tests pass. Longer tests my fail as parts warm up. I don't have that test data yet. I tested Zarlink FO cable assemblies, 10 transceivers in total, on the FPGA 0, 2 and 3 side of one BEE2 and the BEE2 board would lock up. Not operational. The BEE2's TI PT6521 8Amp @ 3.3V integrated switching regulator at location P26 isn't able to power the usual loads on the board and more than 8 of the Zarlink FO transceivers. Maybe less; I haven't explored all the options. I don't yet have the data on the on-board loads and such to show the math. This component, P26, isn't overheating (w/ proper heatsink) rather it momentarily goes into over current shutdown; fo links shut off, shortly later comes back online and the on/off cycling continues. The BEE2 is not usable in such a state. Summary, before configuring a system to use more than just a few active CX4 links check that the BEE2 will actually be able to power those devices. Matt Dexter On Fri, 3 Apr 2009, Matt Dexter wrote: > We experience good performance iBob-> BEE2 over many 1m WL Gore > IBN6800-1 cables. > > We also experience good performance iBob->BEE2 over quite a few 1.5m > WL Gore IBN6800-1.5 cables. We have experienced no unusual delays in > receiving the 1.5m cables we have ordered even though they are non standard. > > We ran some limited tests with 2m meterIBN6800-2 iBob->BEE2 and they > worked better than 3m and almost as good as 1.5m (surprise surprise). > 1.5m were long enough for us so we use those. > > We experience difficulties over 3m IBN6800-3 for iBob->BEE2 and will > not use them in this way unless there is an emergency. > > We use Zarlink fiber optic CX4 cables for 3m and longer. > > We also have fans, Sunon GM0504PEV1-8GN, in addition to heatsinks on > every iBob's FPGA. > > Matt Dexter > > On Fri, 3 Apr 2009, G Jones wrote: > > > Hello, > > I know this question comes up a lot, but is a 3 meter XAUI cable > > usable for transmitting data from an iBOB to a BEE2? I have ready > > Suraj's memo about testing the link integrity versus preemphasis and > > differential swing, in which he says packets were always lost > > eventually. Is this common in other people's experience? The memo > > mentions that tests were also performed with 1 meter cables, but > > results are not mentioned for those tests. Do 1 meter cables perform > > better? In my system, I can make all the cables 1 meter, but the > > routing is more difficult. A 1.5 meter cable would be ideal, but is > > not standard. As such, I would like to use 3 meter cables, but am > > concerned about data integrity. If 1 meter cables are known to be > > more reliable than 3 meter cables for this application, I will use them and deal with the cable routing issues. > > Thanks, > > Glenn > > > >
Effect of Temperature on XAUI Link Stability.doc
Description: Effect of Temperature on XAUI Link Stability.doc
