AX88140AP datasheet(24/46 Pages) ASIX

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AX88140A

PRELIMINARY

ASIX ELECTRONICS CORPORATION

R/W/C

TJT - Transmit Jabber Time-out

Indicates that the transmit jabber timer expired, meaning that the AX88140A transmitter had

been excessively active. The transmission process is aborted and placed in the stopped state.

This event causes the transmit jabber time-out TDES0<14> is set.

R/W/C

TU - Transmit Buffer Unavailable

Indicates that the next descriptor on the transmit list is owned by the host and cannot be acquired

by the AX88140A.The transmission process is suspended. To resume processing transmit

descriptors, the host should change the ownership bit of the descriptor and then issue a transmit

poll demand command.

R/W/C

TPS - Transmit Process Stopped

Asserts when the transmit process enters the stopped state.

R/W/C

TI - Transmit Interrupt

Indicates that a frame transmission was completed, while TDES1<31> is asserted in the first

descriptor of the frame.

Tab - 20 REG5 Status Register Description

4.2.7 Operation Mode Register (REG6)

REG6 establishes the receive and transmit operating modes and commands.

REG6 should be the last REG to be written as part of initialization.

Field

R/W/C

Description

Reserved

All incoming packets will be received

R/W

RA - Receive All

Filtering mode

29:25

Reserved.--Written as “0” for future compatibility concern.

Enable Scrambler

R/W

SCR - Scrambler Mode

Disable Scrambler

PCS functions are active

R/W

PCS - PCS Mode

MII/SYM port is not selected

Threshold is 10Mb/s

R/W

TTM - Transmit Threshold Mode

Threshold is 100Mb/s

Enable Store and Forward

R/W

SF - Store and Forward

Disable Store and Forward

Reserved.--Written as “0” for future compatibility concern.

Heartbeat Disable

R/W

HBD - Heartbeat Disable

Heartbeat Enable

MII/SYM port is selected.

R/W

PS - Port Select

SRL port is selected

17:16

Reserved.--Written as “0” for future compatibility concern.

TR - Threshold Control Bits

The threshold value has a direct impact on the AX88140A bus arbitration scheme . Transmission starts when

the frame size within the transmit FIFO

is larger than the threshold. In addition, full frames with a length

less than the threshold are also transmitted. The transmit process must be in the stopped state to change these

bits.

Controls the selected threshold level for the AX88140A transmit FIFO. Four threshold levels are allowed.

REG6<18>=0

REG6<18>=1

REG6<21>

REG6<15:14>

REG6<22>=X

REG6<22>=1

REG6<22>=0

15:14

R/W

128

256

128

512

160

1024

Store & Forward

Start Transmission

R/W

ST - Start/Stop Transmission

Stop Transmission

Enable force collision

R/W

FC - Force Collision Mode

Disable force collision

00 Normal

01 Internal Loop-back

11:10

R/W

OM - Operating Mode

10 External Loop-back

R/W

FD - Full-Duplex Mode

Full-Duplex

AX88140AP Datasheet(PDF) 24 Page - ASIX Electronics Corporation

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