AX88140AP ETC, AX88140AP Datasheet - Page 24

• Manufacturer Part Number: AX88140AP
• Description: Fast Ethernet MAC Controller
• Manufacturer: ETC

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.
4.2.7 Operation Mode Register (REG6)
Field
29:25
17:16
15:14
11:10
31
30
24
23
22
21
20
19
18
13
12
9
3
2
1
0
AX88140A
R/W/C
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
-
-
-
-
R/W/C
R/W/C
R/W/C
R/W/C
Reserved
RA - Receive All
Reserved.--Written as “0” for future compatibility concern.
SCR - Scrambler Mode
PCS - PCS Mode
TTM - Transmit Threshold Mode
SF - Store and Forward
Reserved.--Written as “0” for future compatibility concern.
HBD - Heartbeat Disable
PS - Port Select
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.
ST - Start/Stop Transmission
FC - Force Collision Mode
OM - Operating Mode
FD - Full-Duplex Mode
REG6<21>
0
0
0
0
1
Tab - 20 REG5 Status Register Description
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.
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.
TPS - Transmit Process Stopped
Asserts when the transmit process enters the stopped state.
TI - Transmit Interrupt
Indicates that a frame transmission was completed, while TDES1<31> is asserted in the first
descriptor of the frame.
REG6<15:14>
XX
00
01
10
11
REG6<18>=0
REG6<22>=X
24
Store & Forward
Description
128
160
72
96
00 Normal
01 Internal Loop-back
10 External Loop-back
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
All incoming packets will be received
Filtering mode
Enable Scrambler
Disable Scrambler
PCS functions are active
MII/SYM port is not selected
Threshold is 10Mb/s
Threshold is 100Mb/s
Enable Store and Forward
Disable Store and Forward
Heartbeat Disable
Heartbeat Enable
MII/SYM port is selected.
SRL port is selected
Start Transmission
Stop Transmission
Enable force collision
Disable force collision
Full-Duplex
ASIX ELECTRONICS CORPORATION
REG6<18>=1
REG6<22>=1
Store & Forward
128
160
72
96
PRELIMINARY
REG6<18>=1
REG6<22>=0
Store & Forward
1024
128
256
512