LAN9211 datasheet(28/147 Pages) SMSC

28 / 147 page

High-Performance Small Form Factor Single-Chip Ethernet Controller with HP Auto-MDIX Support

Datasheet

Revision 2.9 (03-01-12)

SMSC LAN9211

DATASHEET

Destination Address Source Address ……………FF FF FF FF FF FF

00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55 00 11 22 33 44 55

…CRC

It should be noted that Magic Packet detection can be performed when LAN9211 is in the D0 or D1

power states. In the D0 state, “Magic Packet” detection is enabled when the MPEN bit is set. In the

D1 state, Magic Packet detection, as well as wake-up frame detection, are automatically enabled when

the device enters the D1 state.

3.6

Checksum Offload Engines (COE)

The LAN9211 contains two checksum offload engines, which offload the calculation of the 16-bit

checksum for transmitted and received Ethernet frames. The functionality of the checksum offload

engines is described in the following sections:

Receive Checksum Offload Engine (RXCOE)

Transmit Checksum Offload Engine (TXCOE)

3.6.1

Receive Checksum Offload Engine (RXCOE)

The receive checksum offload engine provides assistance to the CPU by calculating a 16-bit checksum

for a received Ethernet frame. The RXCOE readily supports the following IEEE802.3 frame formats:

Type II Ethernet frames

SNAP encapsulated frames

Support for up to 2, 802.1q VLAN tags

The resulting checksum value can also be modified by software to support other frame formats.

The RXCOE has two modes of operation. In mode 0, the RXCOE calculates the checksum between

the first 14 bytes of the Ethernet frame and the FCS. This is illustrated in Figure 3.2.

Figure 3.2 RXCOE Checksum Calculation

DST

SRC

Frame Data

Calculate Checksum

LAN9211 数据表(PDF) 28 Page - SMSC Corporation