AX88772

USB to 10/100 Fast Ethernet/HomePNA Controller

4.1.4

Phy Register Offset for Interrupt Endpoint (0Fh)

Bit 15

Bit 14

Bit 13

Bit 12

Bit 11

Bit 10

Bit 9

Bit 8

Reserved

Phy Register Offset 1

Bit 7

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Reserved

Phy Register Offset 2

Phy Register Offset 1: Fill in Phy’s Register Offset of Primary Phy here. Upon each Interrupt Endpoint issued, its

register value will be reported in byte# 5 and 6 of Interrupt Endpoint packet.

Phy Register Offset 2: Fill in Phy’s Register Offset of Primary Phy here. Upon each Interrupt Endpoint issued, its

register value will be reported in byte# 7 and 8 of Interrupt Endpoint packet.

4.1.5

Max Packet Size High/Low Byte (10h)

Fill in this field the maximum RX/TX MAC frame size supported by this ASIC. The number must be even number in

terms of byte and should be less than or equal to 2500 bytes.

4.1.6

Primary/Secondary Phy_Type and Phy_ID (11h)

The 3 bits Phy_Type field for both Primary and Secondary Phy is defined as follows,

3’b000: 10/100 Ethernet Phy or 1M HOME Phy.

3’b111: non-supported Phy. For example, the High Byte value of “E0h” means that secondary Phy is not supported.

Note that the Phy_ID of the embedded 10/100 Ethernet PHY is being assigned to 5’b1_0000.

4.1.7

Pause Frame High Water and Low Water Mark (12H)

When operating in full-duplex mode, correct setting of this field is very important and can affect the overall packet

receive throughput performance in a great deal. The High Water Mark is the threshold to trigger sending of Pause frame

and the Low Water Mark is the threshold to stop sending of Pause frame. Note that each free buffer count here represents

256 bytes of packet storage space in SRAM.

Total free buffer count = 80

Stop sending Pause frame when free buffer > Low Water Mark

Start sending Pause frame when free buffer < High Water Mark

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