ASIX ELECTRONICS CORPORATION

11

AX88178 L

USB to 10/100/1000 Gigabit 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 when Jumbo Frame mode is disabled. The

number must be even number in terms of byte and should be less than or equal to 2500 bytes. When Jumbo Frame mode

is enabled, the maximum MAC frame size is fixed to 9216 bytes and this setting is ignored.

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 (Link reports as normal case).

3’b100: Special case 1 (Link reports as always active).

3’b001: Gigabit Ethernet Phy.

3’b111: non-supported Phy. For example, the High Byte value of “E0h” in EEPROM offset of “11h” means that

secondary Phy is not supported.

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.

When Jumbo frame mode is not disabled, user can fill in a smaller value in High Water Mark and a larger value in Low

Water Mark fields to have more efficient use of SRAM for packet buffering.

Total free buffer count = 80

Start sending Pause frame when free buffer < High Water Mark

0

Stop sending Pause frame when free buffer > Low Water Mark