LAN9221-ABZJ Standard Microsystems (SMSC), LAN9221-ABZJ Datasheet - Page 34

• Manufacturer Part Number: LAN9221-ABZJ
• Manufacturer: Standard Microsystems (SMSC)

Specifications of LAN9221-ABZJ

• Operating Supply Voltage (typ): 1.8/2.5/3.3V
• Operating Supply Voltage (min): 1.62V
• Operating Supply Voltage (max): 3.6V
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 56
• Lead Free Status / RoHS Status: Compliant

Revision 2.7 (03-15-10)
3.6.2.1
3.7
3.7.1
3.7.2
FIELD
31:28
27:16
15:12
11:0
Note: When the TXCOE is enabled, the third DWORD of the pre-pended packet is not transmitted.
Note: The TX checksum preamble must be DWORD-aligned (i.e., the two least significant bits of the
Note: Software applications must stop the transmitter and flush the TX data path before changing the
TX Checksum Calculation
The TX checksum calculation is performed using the same operation as the RX checksum shown in
Section
transmitted checksum is the one’s-compliment of the final calculation.
Bus Writes
The host processor is required to perform two contiguous 16-bit writes to complete a single DWORD
transfer. This DWORD must begin and end on a DWORD address boundary (A[2] and higher, cannot
change during a sixteen bit write). No ordering requirements exist. The processor can access either
the low or high word first, as long as the next write is performed to the other word. If a write to the
same word is performed, the LAN9221/LAN9221i disregards the transfer.
Bus Reads
The host processor is required to perform two consecutive 16-bit reads to complete a single DWORD
transfer. This DWORD must begin and end on a DWORD address boundary (A[2] and higher, cannot
change during a sixteen bit read). No ordering requirements exist. The processor can access either
the low or high word first, as long as the next read is performed from the other word. If a read to the
same word is performed, the data read is invalid and should be re-read. This is not a fatal error. The
LAN9221/LAN9221i will reset its read counters and restart a new cycle on the next read.
Host Bus Operations
RESERVED
TXCSLOC - TX Checksum Location
This field specifies the byte offset where the TX checksum will be inserted in the TX packet. The
checksum will replace two bytes of data starting at this offset.
Note:
RESERVED
TXCSSP - TX Checksum Start Pointer
This field indicates start offset, in bytes, where the checksum calculation will begin in the associated
TX packet.
Note:
However, 4 bytes must be added to the packet length field in TX Command ‘B’.
Data Start Offset fields in TX Command “A” must be zero). Any valid buffer end alignment
setting can be used.
state of the TXCOE_EN bit. However, the CK bit of TX Command ‘B’ can be set or cleared on
a per-packet basis.
3.6.1.1, with the exception that the calculation starts as indicated by the preamble, and the
The TX checksum cannot be inserted in the MAC header (first 14 bytes) or in the last 4
bytes of the TX packet.
The data checksum calculation must not begin in the MAC header (first 14 bytes) or in
the last 4 bytes of the TX packet.
Table 3.7 TX Checksum Preamble
DATASHEET
34
DESCRIPTION
High-Performance 16-bit Non-PCI 10/100 Ethernet Controller with Variable Voltage I/O
SMSC LAN9221/LAN9221i
Datasheet