LAN9312 Datasheet, PDF (129/458 Pages) SMSC Corporation – High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface

High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
„ 17-Bytes of payload data
„ 16-Byte “Buffer End Alignment”
Figure 9.5 illustrates the TX command structure for this example, and also shows how data is passed
to the TX Data FIFO.
Data Written to the
Memory Mapped
TX Data FIFO Port
31
0
TX Command 'A'
Buffer End Alignment = 1
TX Command 'A'
Data Start Offset = 7
First Segment = 1
TX Command 'B'
Last Segment = 0
Buffer Size = 79
7-Byte Data Start Offset
TX Command 'B'
Packet Length = 111
Data Passed to the
TX Data FIFO
TX Command 'A'
TX Command 'B'
79-Byte Payload
Pad DWORD 1
10-Byte
End Padding
31
TX Command 'A'
Buffer End Alignment = 1
Data Start Offset = 0
First Segment = 0
Last Segment = 0
Buffer Size = 15
TX Command 'B'
Packet Length = 111
0
TX Command 'A'
TX Command 'B'
15-Byte Payload
1B
31
0
TX Command 'A'
Buffer End Alignment = 1
10-Byte
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Data Start Offset = 10
TX Command 'B'
First Segment = 0
Last Segment = 1
10-Byte
Buffer Size = 17
Data Start Offset
TX Command 'B'
Packet Length = 111
17-Byte Payload Data
79-Byte Payload
TX Command 'A'
15-Byte Payload
TX Command 'A'
17-Byte Payload
NOTE: Extra bytes
between buffers are
not transmitted
SMSC LAN9312
5-Byte End Padding
Figure 9.5 TX Example 1
129
DATASHEET
Revision 1.2 (04-08-08)