AX88141

PRELIMINARY

ASIX ELECTRONICS CORPORATION

22

CONFIDENTIAL

3

R/W/C

TJT - Transmit Jabber Time-out

Indicates that the transmit jabber timer expired, meaning that the AX88141 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.

2

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

AX88141.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.

1

R/W/C

TPS - Transmit Process Stopped

Asserts when the transmit process enters the stopped state.

0

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 - 26 REG5 Status Register Description

4.2.9 Operation Mode Register (REG6)

1.

REG6 establishes the receive and transmit operating modes and commands.

2.

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

Field

R/W/C

Description

31

-

Reserved

1

All incoming packets will be received

30

R/W

RA - Receive All

0

Filtering mode

29:23

-

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

1

Threshold is 10Mb/s

22

R/W

TTM - Transmit Threshold Mode

0

Threshold is 100Mb/s

1

Enable Store and Forward

21

R/W

SF - Store and Forward

0

Disable Store and Forward

20

-

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

1

Heartbeat Disable

19

R/W

HBD - Heartbeat Disable

0

Heartbeat Enable

1

MII port is selected.

18

R/W

PS - Port Select

0

N/A

17:16

-

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

TR - Threshold Control Bits

The threshold value has a direct impact on the AX88141 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 AX88141 transmit FIFO. Four threshold levels are allowed.

REG6<18>=0

REG6<18>=1

REG6<18>=1

REG6<21>

REG6<15:14>

REG6<22>=X

REG6<22>=1

REG6<22>=0

15:14

R/W

0

00

72

72

128

0

01

96

96

256

0

10

128

128

512

0

11

160

160

1024

1

XX

Store & Forward

Store & Forward

Store & Forward

1

Start Transmission

13

R/W

ST - Start/Stop Transmission

0

Stop Transmission

1

Enable force collision

12

R/W

FC - Force Collision Mode

0

Disable force collision

00 Normal

01 Internal Loop-back

11:10

R/W

OM - Operating Mode

10 External Loop-back

1

Full-Duplex

9

R/W

FD - Full-Duplex Mode

0

Half-Duplex

1

Accept broadcast packet

8

R/W

RB - Receive broadcast packet

0

Reject broadcast packet

1

Enable Pass All Multicast

7

R/W

PM - Pass All Multicast

0

Disable Pass All Multicast

6

R/W

PR - Promiscuous Mode

1

Indicates that any incoming valid frame is received, regardless

of its destination address.