SMSC LAN9311 User Manual

Two Port 10/100 Managed Ethernet Switch with 16-Bit Non-PCI CPU Interface

Datasheet

SMSC LAN9311/LAN9311i

131

Revision 1.4 (08-19-08)

DATASHEET

9.8.6.2

TX Example 2

In this example, a single 183-Byte Ethernet packet will be transmitted. This packet is in a single buffer
as follows:

2-Byte “Data Start Offset”

183-Bytes of payload data

4-Byte “Buffer End Alignment”

illustrates the TX command structure for this example, and also shows how data is passed

to the TX Data FIFO. Note that the packet resides in a single TX Buffer, therefore both the FS and LS
bits are set in TX command ‘A’.

Figure 9.6 TX Example 2

TX Command 'A'

TX Command 'B'

Data Written to the

Memory Mapped

TX Data FIFO Port

TX Command 'B'

183-Byte Payload Data

Data Start Offset = 6
First Segment = 1
Last Segment = 1
Buffer Size =183

Packet Length = 183

TX Command 'A'

TX Command 'B'

Data Passed to the

TX Data FIFO

Buffer End Alignment = 0

3B End Padding

TX Command 'A'

6-Byte Data Start Offset

183-Byte Payload Data

NOTE: Extra bytes between buffers
are not transmitted