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During today’s XLAUI/CAUI Ad Hoc call I picked up some action items to E-mail out some items. Here are these items.
1 There was significant debate as to whether the XLAUI/CAUI IEEE specification should be just for chip to chip, or whether additional test point specifications should be included for host/module. Ie whether the host/module specs for the retimed interface are included in 802.3 or left for development by other groups such as MSA’s or SFF committee. Jeff volunteered to ask CFP members their views, however I think it is an appropriate topic for the complete group. (FYI The non-retimed PPI host/module interface specs are being developed in IEEE in Clause 86).
2 Detailed specification discussion.
Proposals have been made to define rise/fall times and De-emphasis.
To define rise/fall times in a reproducible manner, particularly for waveforms with de-emphasis the 0 and 100% levels have to be defined in an un-ambiguous manner. Clause 86 is using the stable levels on the square wave pattern (the same levels as used for OMA/VMA measurement). I think this is the best method, as I think this probably best predicts system performance. Alternatives are however the peak levels as defined for De-emphasis (see later), or the average value of the center 20% of the eye diagram (as used to define zero and one values in the eye diagram).
A proposal has been made to define De-emphasis as the ratio between peak-peak values and the stable one/zero levels. Again un-ambiguous definitions are required for peak-peak and stable one/zero. The proposal suggested that the square wave pattern is used. The stable one/zero levels could be defined identically to VMA (average value over center 20% of the one and zero levels of the square wave). Other definitions are possible, but I see no advantage in creating a different definition. For the peak values it was suggested that it should be the value at 0.5UI, however on the call zero time had not been defined. One definition that I think is reasonable is the zero crossing time of the square wave. Another definition for the zero time would be the zero crossing time of the 101010 pattern. (however this has the disadvantage of requiring a 101010 test pattern that is not presently defined.). Yet another definition could be to use the mean crossing point as used to align an eye mask. There are also other possible definitions that do not require establishing an exact zero time reference. Peak could be defined as the peak value at any time within an averaged square wave. Peak-Peak could be defined as the amplitude of a 101010 averaged signal (again however this has the disadvantage of requiring the 101010 test pattern). Personally I think the peak value at any time within the averaged square wave is probably the easiest definition and recommend it’s use unless there are reasons not to do this. My second choice would be 0.5UI after the zero crossing of the square wave.
PMTS Standards & Technology
Tel 303 530 3189 x7533.
Dear 802.3ba Colleagues,
I'd like to schedule the next meeting for the XLAUI / CAUI Ad Hoc as follows:
Friday December 19th 8:30am - 10:30am
Dial-in Number (Canada & USA) :1 877 234 4610
Participant Conference Access code: 4405734 # (see below for additional phone numbers)
Presentations should focus on technical details / values related to the nAUI specification. In particular, I would like to focus on the channel specification & de-emphasis proposals.
Anyone wishing to present, please follow the guidelines described on the Procedure for Presenters web page:
If you are planning to participate please take a moment to read the IEEE patent policy available here: http://standards.ieee.org/board/pat/pat-slideset.ppt.
* Participant Conference Access code: 4405734 #
* Dial-in Number:416 883
* Dial-in Number:1 877 234
Analog & Mixed-Signal Products
Phone: 905 632 2999 x 1610