Intel® 82579 Gigabit Ethernet—Programmer’s Visible State
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Table 43. D iagnostics Status Register (Linking Disabled) - Address 31
Bits Field Type Default Description
15:14 TDR Fault Type Pair X R/W, SC 11b
The first time this register is read after automatic
TDR analysis completed, it indicates the fault type
for pair A. The second time it is read, it indicates
the fault type for pair B, the third for pair C, and the
fourth for pair D. The pair indication bits (Register
31, bits 1:0) indicate to which pair the results
correspond to. Bits 13:12 of Register 30 can be
used to specify a pair other than pair A as the first
dimension that is reported.
A value of 01b indicates either an open or a short. If
bits 13:10 of Register 31 equal 0000b, it is an open.
For all other values of bits 13:10 in Register 31,
each bit indicates a short to pair A, B, C, and D.
A value of 11b indicates that the results for this pair
are invalid. An invalid result usually occurs when
unexpected pulses are received during the TDR
operation. For example, from a remote PHY that is
also doing TDR or trying to brink up a link. When an
invalid result is indicated, the distance in bits 9:2 of
Register 31 is 0xFF and should be ignored.
11b = Result invalid
10b = Open or short found on pair X.
01b = Strong impedance mismatch found on pair X.
00b = Good termination found on pair X.
13 Short Between Pairs
X and D RO 0b
The first time these bits are read after automatic
TDR analysis has completed, indicate a short
between pair A and pair A, B, C, and D,
respectively. The second time they are read,
indicate a short between pair B and pair A, B, C,
and D, respectively. The third time with pair C and
the fourth time with pair D. It then cycles back to
pair A. The pair indication bits (Register 31, bits
1:0) indicate to which pair the results correspond
to. Bits 13:12 of Register 30 can be used to specify
a pair other than pair A as the first dimension that
is reported.
1b = Short between pairs X and D.
0b = No short between pairs X and D.
12 Short Between Pairs
X and C RO 0b
The first time these bits are read after automatic
TDR analysis has completed, indicate a short
between pair A and pair A, B, C, and D,
respectively. The second time they are read,
indicate a short between pair B and pair A, B, C,
and D, respectively. The third time with pair C and
the fourth time with pair D. It then cycles back to
pair A. The pair indication bits (Register 31, bits
1:0) indicate to which pair the results correspond
to. Bits 13:12 of Register 30 can be used to specify
a pair other than pair A as the first dimension that
is reported.
1b = Short between pairs X and C.
0b = No short between pairs X and C.