RTL8181 ETC, RTL8181 Datasheet - Page 26

• Manufacturer Part Number: RTL8181
• Description: Wireless LAN Access Point/Gateway Controller
• Manufacturer: ETC

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3
2
1
0
Transmit Descriptor
Tx Descriptor Format (before transmitting, OWN=1, LGSEN=0, Tx command mode 1)
O
W
N
=
1
CONFIDENTIAL
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9
Byte
Offset#
0
0
0
0
0
0
0
0
0
E
O
R
F
S
MDM
MDO
MDI
MDC
L
S
Bit# Bit Name Description
31
30
29
28
27
26-19 -
18
17
16
L
G
S
E
N
=
0
R
E
S
V
OWN
EOR
FS
LS
LGSEN
IPCS
UDPCS
TCPCS
R
E
S
V
RESV
R
E
S
V
R
E
S
V
Management Data Mode:
0: MDIO pin is input. MDI bit reflects the state of
MDIO pin. The default value is "0".
1: MDIO pin is output, and the state of MDIO pin
reflects with MDO bit.
MII Management Data-OUT: Used by the NIC to
write data to the MDIO pin.
MII Management Data-IN: Used by the NIC to
read data from the MDIO pin.
Management Data Clock: This bit reflects the state
of MDC pin.
R
E
S
V
When set, indicates that the descriptor is owned by NIC, and the data
relative to this descriptor is ready to be transmitted. When cleared,
indicates that the descriptor is owned by host system. NIC clears this
bit when the relative buffer data is transmitted. In this case, OWN=1.
End of descriptor Ring. When set, indicates that this is the last
descriptor in descriptor ring. When NIC’s internal transmit pointer
reaches here, the pointer will return to the first descriptor of the
descriptor ring after transmitting the data relative to this descriptor.
First segment descriptor. When set, indicates that this is the first
descriptor of a Tx packet, and this descriptor is pointing to the first
segment of the packet.
Last segment descriptor. When set, indicates that this is the last
descriptor of a Tx packet, and this descriptor is pointing to the last
segment of the packet.
A command bit. TCP/IP-Large-send operation enables. Driver sets this
bit to enable NIC to offload CPU operation for TCP/IP fragmentation.
Reserved.
A command bit. IP checksum offload. Driver sets this bit to ask NIC to
offload IP checksum.
A command bit. UDP checksum offload. Driver sets this bit to ask NIC
to offload UDP checksum.
A command bit. TCP checksum offload enable. Driver sets this bit to
ask NIC to offload TCP checksum.
R
E
S
V
R
E
S
V
R
E
S
V
TX_BUFFER_ADDRESS
I
P
C
S
U
D
P
C
S
T
C
P
C
S
Dummy
26
Frame_Length
VLAN_TAG
8
7
R/W 0
R/W X
R
R/W 0
6
5
X
4
3
2
1
0
Offset 0
Offset 4
Offset 8
Offset 12
RTL8181
v1.0