83C795 datasheet(45/136 Pages) SMSC

45 / 136 page

Bit 3: GROUP, Receive Multicast Frames

When GR OUP = 1, this bit enables reception of all

frames that:

• have multicast addresses

• pass the multicast address hashing filter

Bit 2: BROAD, Receive Broadcast Frames

When BR OAD = 1, this bit enables reception of all

frames having a Broadcas t (all ’1’s ) des tination

address .

Bit 1: RUNTS, Receive Runts Frames

When R UNT S = 1, this bit allows reception of

frames having les s than 64 bytes , provided that

they otherwis e meet the requirements of the 802.3

protocol.

Bit 0: SEP, Save Errored Packets

When S E P = 1, it directs the receive unit to s ave

packets having CR C or frame alignment errors in

the buffers .

5.2.24 RDOWNH - Buffer Room Remaining

High Register

Linked-List Map R ead/Write Port = 2:19

T his regis ter contains the upper 8 bits of a regis ter

pair us ed by the DMA controller as a scratch pad

for the buffer room remaining count during the

reception proces s .

Note

Writing to these registers while commu-

nication is taking place may cause er-

rors in the DMA process.

BIT

RDOWNH

RESET

A15

A14

A13

A12

3A11

A10

A09

A08

5.2.25 RDOWNL - Buffer Room Remaining

Low Register

Linked-List Map R ead/Write Port = 2:18

T his regis ter contains the lower 8 bits of a regis ter

pair us ed by the DMA controller as a scratch pad

for the buffer room remaining count during the

reception proces s .

Note

Writing to these registers while commu-

nication is taking place may cause er-

rors in the DMA process.

BIT

RDOWNL

RESET

A07

A06

A05

A04

A03

A02

A01

A00

5.2.26 REND - Receive Buffer End Register

Linked-List Map R ead Port = 2:12 Linked-Lis t Map

Write Port = 0:12

T his regis ter holds the upper 8 bits of the firs t

addres s beyond the end of the receive buffer

descriptor table. T he lower 8 bits are as s umed to

be zero. T he table lies between the numbers

(R BE GIN * 256) and (R E ND * 256 - 1). R efer to

page 88 for more details .

BIT

REND

RESET

RE15

RE14

RE13

RE12

RE11

RE10

RE9

RE8

83C795

ETHERNET SYSTEM CONTROLLER REGISTERS

83C795 Datasheet(PDF) 45 Page - SMSC Corporation

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