KSZ9567R datasheet(23/233 Pages) MICROCHIP

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DS00002329E-page 23

KSZ9567R

Fast Link-up mode significantly reduces 100BASE-TX link-up time by disabling both auto-negotiation and auto MDI/

MDI-X, and fixing the TX and RX channels. This mode is enabled or disabled by the LED2_1 strapping option. It is not

set by registers, so fast link-up is available immediately upon power-up. Fast Link-up is available at power-up only for

100BASE-TX link speed, which is selected by strapping the LED4_0 pin high. Fast Link-up is also available for 10BASE-

Te, but this link speed must first be selected via a register write.

Fast Link-up is intended for specialized applications where both link partners are known in advance. The link must also

be known so that the fixed transmit channel of one device connects to the fixed receive channel of the other device, and

vice versa. The TX and RX channel assignments are determined by the MDI/MDI-X strapping option on LED2_0.

If a device in Fast Link-up mode is connected to a normal device (auto-negotiate and auto-MDI/MDI-X), there will be no

problems linking, but the speed advantage of Fast Link-up will not be realized.

For more information on configuration straps, refer to Section 3.2.1, "Configuration Straps," on page 16.

4.1.9

LinkMD® CABLE DIAGNOSTICS

The LinkMD® function utilizes Time Domain Reflectometry (TDR) to analyze the cabling for common cabling problems,

such as open circuits, short circuits and impedance mismatches.

LinkMD® works by sending a pulse of known amplitude and duration down the MDI or MDI-X pair, and then analyzing

the shape of the reflected signal to determine the type of fault. The time duration for the reflected signal to return pro-

vides the approximate distance to the cabling fault. The LinkMD® function processes this TDR information and presents

it as a numerical value that can be translated to a cable distance.

A LinkMD test is initiated individually for each PHY and for a specific PHY differential pair.

4.1.9.1

Usage

To run a LinkMD test on all four pairs of one PHY, follow this flow.

Disable auto-negotiation: Write 0 to of register 0xN100-0xN101 bit 12.

Configure register 0xN112-0xN113 to enable master-slave manual configuration mode.

Start cable diagnostic by writing 1 to register 0xN124-0xN125 bit 15. This enable bit is self-clearing.

Wait (poll) for register 0xN124-0xN125 bit 15 to return 0, which indicates that the cable diagnostic test is com-

pleted. Alternatively, wait 250ms.

Read cable diagnostic test status in register 0xN124-0xN125 bits [9-8]. The results are:

a) 00 = normal operation

b) 01 = open condition detected in cable (valid result)

10 = short condition detected in cable (valid result)

d) 11 = cable diagnostic test invalid (test failed)

The ‘11’ case occurs when the PHY is unable to shut down the link partner. In this instance, the test is not run because

it would be impossible for the PHY to determine if the detected signal is a reflection of the signal generated or a signal

from another source.

For status 01 or 10, read the Cable Diagnostic Result in register 0xN124-0xN125 bits [7:0]. Get distance to fault

by the following formula:

Distance to fault (meters) = 0.8 * (Cable Diagnostic Result – 22).

To test another differential pair on this PHY, change the value of register 0xN124-0xN125 bits [13:12] when initi-

ating the test.

Return the registers to their original values and restart auto-negotiation.

The following script will test the four pairs of port 1. For other ports, change the register addresses accordingly.

“ww” = write word (16-bits) [register] [data]

“rw” = read word (16-bits) [register]

Values are hexadecimal.

ww 1100 0140

# initialization

ww 1112 1000

# initialization

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