DP83255AVF datasheet(17/96 Pages) NSC

Part #	DP83255AVF

Description	PLAYER Device (FDDI Physical Layer Controller)

PDF	96 Pages

Scroll/Zoom	100%

Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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17 / 96 page

40 Modes of Operation (Continued)

433 External Loopback

The External Loopback mode can be used to test the func-

tionality of the PLAYER device and to test the data paths

between the PLAYER CRD and BMAC devices before

transmitting and receiving data through the network

When in the External Loopback mode the PLAYER device

performs the following functions

Directs the output data of the Transmitter Block to the

external Loopback Data pins (LBDg) which are normal-

ly connected to the Clock Recovery Device (see

Figure

2 PLAYER Device Block Diagram)

Outputs Quiet symbols through the PMD Data Request

pins (TXDg)

The level of the Quiet symbols transmitted through the

TXCg pins is programmable through the Transmit Quiet

Level bit of the Mode Register

If both Internal Loopback and External Loopback modes are

selected Internal Loopback mode will have priority over Ex-

ternal Loopback mode

See

Figure 4-3 for a block diagram

TLF10386 – 17

FIGURE 4-3 External Loopback

DP83255AVF Datasheet(PDF) 17 Page - National Semiconductor (TI)