19

IDT77V106L25

Diagnostic Control Register

Address: 0x02

Bit

Type

Initial State

Function

7

R/W

0 = normal

Force TxCLAV Deassert

This feature can be used during line loopback mode to prevent cells from being passed across the Utopia bus for

transmission.

6

R/W

0 = UTOPIA

RxCLAV Operation Select

The UTOPIA standard dictates that during cell mode operation, if the receive FIFO no longer has a complete cell

available for transfer from PHY, RxCLAV is deasserted following transfer of the last byte out of the PHY

to the upstream system. With this bit set, early deassertion of this signal will occur coincident with the end of Payload

byte 44 (as in octet mode for TxCLAV). This provides early indication to the upstream system of this impending

condition.

0 = "Standard UTOPIA RxCLAV"

1 = "Cell mode = Byte mode"

5

R/W

0 = Tri-state

Single/Multi-PHY Configuration Select

0 = single

Never tri-state RxDAY+TA, RxPARITY, and RxSOC

1 = Multi-PHY mode

Tri-state RxDATA, RxPARITY, and RxSOC when

RxEN = 1

4

R/W

0 = normal

RFLUSH = Clear Receive FIFO

This signal is used to tell the TC to flush (clear) all data in the receive FIFO. The TC signals this completion by

clearing this bit.

3

R/W

0 = normal

Insert Transmit Payload Error

Tells TC to insert cell payload errors in transmitted cells. This can be used to test error detection and recovery

systems at destination station, or, under loopback control, at the local receiving station. This payload error is

accomplished by flipping bit 0 of the last cell payload byte.

2

R/W

0 = normal

Insert Transmit HEC Error

Tells TC to insert HEC error in Byte 5 of transmitted cells. This can be used to test error detection and recovery

systems in downstream switches, or, under loopback control, the locak receiving station. The HEC error is

accomplished by flipping bit 0 of the HEC byte.

1, 0

R/W

0 = normal

Loopback Control

bit # 1

0

0

0 Normal mode (receive from network)

1

1 PHY Loopback

1

1 Line Loopback