Product specifications

VT8235 V-Link South Bridge
Revision 1.22 October 24, 2002 -120- Device 18 Function 0 LAN Registers
LAN I/O Registers
Offset 05-00 – Ethernet Address ......................................RW
Unless the EEPROM is disabled, the Ethernet Address is
loaded to this register from the EEPROM every time the
system starts up.
Offset 06 – Receive Control (00h) ....................................RW
7-5 Receive FIFO Threshold
This field determines the threshold required before
data in the receive FIFO is forwarded. When the
FIFO reaches the level selected in this field, data will
start being forwarded.
000 64 byte................................................... default
001 32 byte
010 128 byte
011 256 byte
100 512 byte
101 768 byte
110 1024 byte
111 Store & Forward (data is forwarded after the
entire packet has been received)
4 Physical Address Packets Accepted
0 Packets with a physical destination address are
not accepted........................................... default
1 All packets with a physical destination address
are accepted........................................... default
3 Broadcast Packets Accepted
0 Broadcast packets are rejected .............. default
1 Broadcast packets are accepted
2 Multicast Packets Accepted
0 Multicast packets are rejected ............... default
1 Multicast packets are accepted
1 Small Packets Accepted
0 Packets smaller than 64 bytes are rejected .. def
1 Packets smaller than 64 bytes are accepted
0 Error Packets Accepted
0 Packets with receive errors are rejected ...... def
1 Packets with receive errors are accepted
Offset 07 – Transmit Control (08h)................................. RW
7-5 Transmit FIFO Threshold
This field determines the threshold required before
data in the transmit FIFO is forwarded. When the
FIFO reaches the level selected in this field, data will
start being forwarded.
100T
10T
000 128 byte 64 byte ................................default
001 256 byte 128 byte
010 512 byte 256 byte
011 1024 byte 512 byte
1xx Store & Forward
4 Reserved ........................................always reads 0
3 Backoff Priority Selection
This bit determines the backoff algorithm used when
collision occurs.
0 VIA backoff algorithm
1 NSC compatible backoff algorithm...... default
2-1 Transmit Loopback Mode
00 Normal...................................................default
01 Internal loopback (signal is looped back to the
host from the MAC)
10 MII loopback (signal is looped back to the host
from the PHY)
11 -reserved- (do not program)
0 Reserved ........................................always reads 0