10.0 Internal Registers
(Continued)
10.3 REGISTER DESCRIPTIONS
(Continued)
TRANSMIT CONFIGURATION REGISTER (TCR)
0DH (WRITE)
The transmit configuration establishes the actions of the transmitter section of the ST-NIC during transmission of a packet on
the network.
LB1 and LB0 which select loopback mode power up as 0.
7
6
5
4
3
2
1
0
Ð
Ð
Ð
OFST
ATD
LB1
LB0
CRC
Bit
Symbol
Description
D0
CRC
Inhibit CRC
0: CRC appended by transmitter
1: CRC inhibited by transmitter
In loopback mode CRC can be enabled or disabled to test the CRC logic
D1
LB0
Encoded Loopback Control:
These encoded configuration bits set the type of loopback that is to be
performed. Note that loopback in mode 2 places the ENDEC Module in loopback mode and that D3 of the
and
and
DCR must be set to zero for loopback operation.
D2
LB1
LB1
LB0
Mode 0
0
0
Normal Operation (LPBK
e
0)
Mode 1
0
1
Internal NIC Module Loopback (LPBK
e
0)
Mode 2
1
0
Internal ENDEC Module Loopback (LPBK
e
1)
Mode 3
1
1
External Loopback (LPBK
e
0)
D3
ATD
Auto Transmit Disable:
This bit allows another station to disable the ST-NIC’s transmitter by transmission
of a particular multicast packet. The transmitter can be re-enabled by resetting this bit or by reception of a
second particular multicast packet.
1: Reception of multicast address hashing to bit 62 disables transmitter, reception of multicast address
hashing to bit 63 enables transmitter.
D4
OFST
Collision Offset Enable:
This bit modifies the backoff algorithm to allow prioritization of nodes.
0: Backoff Logic implements normal algorithm.
1: Forces Backoff algorithm modification to 0 to 2
min(3
a
n, 10)
slot times for first three collisions, then follows
standard backoff. (For the first three collisions, the station has higher average backoff delay making a low
priority mode.)
D5
Reserved
Reserved
D6
Reserved
Reserved
D7
Reserved
Reserved
30
Obsolete