DP83932C datasheet(32/98 Pages) NSC

32 / 98 page

40 SONIC Registers (Continued)

433 Receive Control Register

(Continued)

Bits

Description

10 9

LB1LB0 LOOPBACK CONTROL

These encoded bits control loopback operations for MAC loopback ENDEC loopback and Transceiver loopback 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 17)

Note

A hardware reset clears these bits

LB1

LB0

Function

no loopback normal operation

MAC loopback

ENDEC loopback

Transceiver loopback

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 detects this condition

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

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 bit 2 below) The rev C SONIC has the potential to report CRC error’d frames as FAE This bit is also not

set during CRC error’d RUNT packets

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 error occurs)

LBK LOOPBACK PACKET RECEIVED

Indicates that the SONIC has successfully received a loopback packet

PRX PACKET RECEIVED OK

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

DP83932C bảng dữ liệu(PDF) 32 Page - National Semiconductor (TI)