DP83936AVF datasheet(44/104 Pages) NSC

44 / 104 page

60 SONIC-T Registers (Continued)

643 Receive Control Register

(Continued)

Bit

Description

10 9 LB1LB0 LOOPBACK CONTROL

These encoded bits control loopback operations for MAC loopback ENDEC loopback and Transceiver lookback For proper

loopback operation the CAM Address registers and Receive Control register must be initialized to accept the Destination

address of the loopback packet (see Section 38)

LB1 LB0

Function

no loopback normal operation

MAC loopback

ENDEC loopback

Transceiver loopback (Bit

6 of the DCR2 must also be set to 1)

MC MULTICAST PACKET RECEIVED

This bit is set when a packet is received with a Multicast Address

BC BROADCAST PACKET RECEIVED

This bit is set when a packet is received with a Broadcast Address

LPKT LAST PACKET IN RBA

This bit is set when the last packet is buffered into a Receive Buffer Area (RBA) The SONIC-T detects this condition when its

Remaining Buffer Word Count (RBWC01) register is less than or equal to the End Of Buffer Count (EOBC) register (See

Section 542)

CRS CARRIER SENSE ACTIVITY

Set when CRS is active Indicates the presence of network activity

COL COLLISION ACTIVITY

Indicates that the packet received had a collision occur during reception

CRCR CRC ERROR

Indicates the packet contains a CRC error If the packet also contains a Frame Alignment error FAER will be set instead (see

below)

FAER FRAME ALIGNMENT ERROR

Indicates that the incoming packet was not correctly framed on an 8-bit boundary Note if no CRC errors have occurred this bit

is not set (ie this bit is only set when both a frame alignment and CRC errors occur)

LBK LOOPBACK PACKET RECEIVED

Indicates that the SONIC-T has successfully received a loopback packet

PRX PACKET RECEIVED OK

Indicates that a packet has been received without CRC frame alignment length (run packet) errors or collisions

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DP83936AVF Datasheet(PDF) 44 Page - National Semiconductor (TI)