Datasheet

16-bit Non-PCI Small Form Factor 10/100 Ethernet Controller with Variable Voltage I/O & HP Auto-MDIX Support
Datasheet
Revision 2.9 (03-01-12) 64 SMSC LAN9220
DATASHEET
3.13.2 RX Packet Format
The RX status words can be read from the RX status FIFO port, while the RX data packets can be
read from the RX data FIFO. RX data packets are formatted in a specific manner before the host can
read them as shown in Figure 3.26. It is assumed that the host has previously read the associated
status word from the RX status FIFO, to ascertain the data size and any error conditions.
Figure 3.27 shows the RX packet format when the RX checksum is enabled. The RX checksum data
appended to the data payload is treated just as an additional 4-bytes within the RX Data FIFO. The
RX checksum is enabled by setting the RXCOE_EN bit in the COE_CR—Checksum Offload Engine
Control Register. For more information on the RX checksum, refer to Section 3.6.1, "Receive
Checksum Offload Engine (RXCOE)".
Figure 3.26 RX Packet Format
ofs + First Data DWORD
.
.
.
.
Last Data DWORD
031
Host Read
Order
1st
2nd
Last
Optional Pad DWORD0
.
.
Optional Pad DWORDn
Optional offset DWORD0
.
.
Optional offset DWORDn