DP83261AVF datasheet(64/132 Pages) NSC

64 / 132 page

60 Control Information (Continued)

Lost Frame Counter (LFCT)

The Lost Frame Counter (LFCT) is specified in the FDDI MAC Standard It is the count of all instances where a Format Error is

detected in a frame or token such that the credibility of the PDU reception is in doubt

The Lost Frame Counter is incremented when any symbol other than a data or Idle symbol is received between the Starting and

Ending Delimiters of a PDU (this includes parity errors)

Interrupts are available on increment (CILRFRLST) and when the 20-bit counter overflows and wraps around (COLRFRLST)

ACCESS RULES

Address

Read

Write

A8 – ABh

Always

Stop Mode

LFCT0

Zero

LFCT1

Zero

CT(19)

CT(18)

CT(17)

CT(16)

LFCT2

CT(15)

CT(14)

CT(13)

CT(12)

CT(11)

CT(10)

CT(9)

CT(8)

LFCT3

CT(7)

CT(6)

CT(5)

CT(4)

CT(3)

CT(2)

CT(1)

CT(0)

In REV 1 of the BMAC device the Lost Count includes frames stripped on an ODD symbol boundary This may cause larger than

expected counts in Rings where an upstream station produces valid remnants that begin on an ODD symbol boundary (The

Ring Engine converts these remnants to byte aligned remnants so that only the downstream station would increment its Lost

Count) In subsequent revisions remnants that begin on an odd symbol boundary are not considered lost frames and do not

cause the Lost Count to increment

DP83261AVF Datasheet(PDF) 64 Page - National Semiconductor (TI)

DP83261AVF Datasheet(HTML) 64 Page - National Semiconductor (TI)

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