VSC8504-02 datasheet(44/131 Pages) MICROSEMI

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Functional Descriptions

VMDS-10507 VSC8504-02 Datasheet Revision 4.2

3.17.2.1 Copper Interface CRC Counters

Two separate CRC counters are available and reside between the copper interface PCSs and SerDes

MAC interface. There is a 14-bit good CRC counter available through register bits 18E1.13:0 and a

separate 8-bit bad CRC counter available in register bits 23E1.7:0.

3.17.2.2 SerDes Interface CRC Counters

Two separate CRC counters are available and reside between the SerDes media interface PCSs and

SerDes MAC interface. There is a 14-bit good CRC counter available through register bits 28E3.13:0 and

a separate 8-bit bad CRC counter available in register bits 29E3.7:0.

3.17.2.3 SerDes Fiber Media Transmit Counters

Two fiber media transmit counters are available to verify packets being transmitted on the fiber media.

counters.

3.17.3

Far-End Loopback

The far-end loopback testing feature is enabled by setting register bit 23.3 to 1. When enabled, it forces

incoming data from a link partner on the current media interface, into the MAC interface of the PHY, to be

retransmitted back to the link partner on the media interface as shown in the following illustration. In

addition, the incoming data also appears on the receive data pins of the MAC interface. Data present on

the transmit data pins of the MAC interface is ignored when using this testing feature.

Figure 32 •

Far-End Loopback Diagram

3.17.4

Near-End Loopback

When the near-end loopback testing feature is enabled, transmitted data (TXD) is looped back in the

PCS block onto the receive data signals (RXD), as shown in the following illustration. When using this

testing feature, no data is transmitted over the network. To enable near-end loopback, set the device

Figure 33 •

Near-End Loopback Diagram

3.17.5

Connector Loopback

The connector loopback testing feature allows the twisted pair interface to be looped back externally.

When using this feature, the PHY must be connected to a loopback connector or a loopback cable.

Connect pair A to pair B, and pair C to pair D, as shown in the following illustration. The connector

loopback feature functions at all available interface speeds.

Figure 34 •

Connector Loopback Diagram

Link Partner

TXD

RXD

MAC

PHY_port_

Link Partner

TXD

RXD

MAC

PHY_port_

TXD

RXD

MAC

PHY_port_

Cat5

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