LAN9117 Datasheet, PDF (45/114 Pages) SMSC Corporation – HIGH PERFORMANCE SINGLE-CHIP 10/100 NON-PCI ETHERNET CONTROLLER

LAN9117
3.13.6.2 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”
Figure 3-16, "TX Example 2" 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 3-16:
TX EXAMPLE 2
TX Command 'A'
Buffer End Alignment = 0
Data Start Offset = 6
First Segment = 1
Last Segment = 1
Buffer Size =183
Data Written to the
Ethernet Controller
31
0
TX Command 'A'
TX Command 'B'
6-Byte Data Start Offset
TX Command 'B'
Packet Length = 183
Data Passed to the
TX Data FIFO
TX Command 'A'
TX Command 'B'
183-Byte Payload Data
183-Byte Payload Data
3B End Padding
NOTE: Extra bytes between buffers
are not transmitted
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DS00002267A-page 45