I347-AT4 Datasheet, PDF (42/148 Pages) Intel Corporation – Intel® Ethernet Network Connection I347-AT4 Datasheet

I347-AT4—Device Functionality
3.10
Cable Tester
The I347-AT4 uses Time Domain Reflectometry (TDR) to determine the quality of the
cables, shorts, cable impedance mismatch, bad connectors, termination mismatch, and
bad magnetics. The I347-AT4 transmits a signal of known amplitude (+1V) down each
of the four pairs of an attached cable. It conducts the cable diagnostic test on each pair,
testing the MDI_0_0P/N, MDI_0_1P/N, MDI_0_2P/N, and MDI_0_3P/N pairs
sequentially. The transmitted signal continues down the cable until it reflects off of a
cable imperfection.
Cable tester has four modes of operation that is programmable via register 23_5.7:6.
The first mode returns the peak with the maximum amplitude that is above a certain
threshold. The second mode returns the first peak detected that is above a certain
threshold. The third mode measures the systematic offset at the receiver. The fourth
mode measures the amplitude seen at a certain specified distance.
The cable tester is initiated by setting register 23_5.15 to 1b. This bit self clears when
the test completes. Register 23_5.14 is set to a 1b indicating that the TDR results in
the registers are valid.
Each point in the cable testerreflected waveform is sampled multiple times and
averaged. The number of samples to take is programmable via register 23_5.10:8.
Each time the cable tester is enable, the results seen on the four receive channels are
reported in registers 16_5, 17_5, 18_5, and 19_5. Register 23_5.13:11 selects which
channel transmits the test pulse.
When register 23_5.13:11 is set to 000b the same channel reflection is recorded. In
other words, channel 0 transmits a pulse and the reflection seen on channel 0 receiver
is reported. Channel 1 transmits a pulse and the reflection seen on channel 1 receiver
is reported. The same for channel 2 and channel 3.
When register 23_5.13:11 is set to 100b all four receive channels report the reflection
seen by a pulse transmitted by channel 0.
When register 23_5.13:11 is set to 101b all four receive channels report the reflection
seen by a pulse transmitted by channel 1.
When register 23_5.13:11 is set to 110b all four receive channels report the reflection
seen by a pulse transmitted by channel 2.
When register 23_5.13:11 is set to 111b all four receive channels report the reflection
seen by a pulse transmitted by channel 3.
As a result, if only the reflection seen on the same channel is desired the cable tester
should be run with 23_5.13:11 = 000b. If all same channel and cross channel
combinations are desired then the cable tester must be run four times with 23_5.13:11
set to 100b, 101b, 110b, and 111b for the four runs. Registers 16_5, 17_5, 18_5, and
19_5 should be read and stored between each run.
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