SMSC LAN9312 TX Data FIFO, Data Passed to the

High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface

Datasheet

„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
TX Command 'A'	31	0
	TX Command 'A'
Buffer End Alignment = 1
Data Start Offset = 7	TX Command 'B'
First Segment = 1
Last Segment = 0	7-Byte Data Start Offset
Buffer Size = 79
TX Command 'B'
Packet Length = 111

79-Byte Payload

	10-Byte
	End Padding
31	0
TX Command 'A'	TX Command 'A'
Buffer End Alignment = 1
Data Start Offset = 0	TX Command 'B'
First Segment = 0
Last Segment = 0
Buffer Size = 15	15-Byte Payload
TX Command 'B'
	1B
Packet Length = 111
31	0
TX Command 'A'	10-Byte
	TX Command 'A'
Buffer End Alignment = 1	End Offset Padding
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

Data Passed to theTX Data FIFO

TX Command 'A'

TX Command 'B'

79-Byte Payload

TX Command 'A'

15-Byte Payload

TX Command 'A'

17-Byte Payload

NOTE: Extra bytes between buffers are not transmitted

17-Byte Payload Data

5-Byte End Padding

Figure 9.5 TX Example 1

SMSC LAN9312	129	Revision 1.4 (08-19-08)
	DATASHEET