1394b port task group minutes

Tempe meeting, 17 March 1998

1. Provision of additional control space.

Eric Deliot presented a proposal for a new control code mapping. The proposal
to change as motivated by the need for a larger number of control states to be
signaled, due to the BOSS arbitration accelerations. The scheme Eric presented
uses the existing control codewords for packet delimiter information
(DATA_PREFIX, DATA_END, SPEED, and some new BOSS states - ARB_RESET etc) and
reuses data codewords for arbitration signals between packets.

Eric showed  a set of 64 data code points (a subset of the 256 points) that
are Hamming distance 2 apart, thus offering robust control signaling.

The task group is encouraged to review the proposal with a view to adopting
the changes prior to the next meeting. Discussion should be held on the
reflector.

2. Error reporting

Alistair Coles proposed that the port should maintain a count of invalid
codewords in a phy register. This information would be available for higher
level applications to use, but the port itself would take no action on the
basis of the error count. There was some discussion of the operation of the
register, with a general concensus that the register should not wrap to zero.

Also proposed that the port should adopt a similar algorithm for loss of sync
detection as fibrechannel.


3. Test modes
Alistair Coles proposed that a port should provide capability for the
transmitter scrambler to be disabled for the purposes of testing. This would
allow testers to send a deterministic pattern of codewords on the wire for
exercising a DUT receive circuits. There was some discussion as to whether a
descrambler disable bit should also be provided. This might allow users to
operate a link with no scrambler, which could cause an EMC problem. We agreed
that the spec. should not require but not prohibit descrambler disabling.

Alistair also requested further proposals for test provision from members of
the task group.

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Alistair Coles           Hewlett-Packard Laboratories
                         Filton Rd,Bristol,BS12 6QZ,UK
                         Direct Dial: +44 117 922 8750
anc@hplb.hpl.hp.com      Fax:         +44 117 922 9286
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