LAN83C175 Datasheet, PDF (49/92 Pages) SMSC Corporation – Ethernet CARDBUS Integrated Controller With Modem Support

D2 D1 Mode
0 0 Normal operation.
0 1 Internal loopback.
Packets
transmitted are internally looped back
to the receiver without transmission
to the MII.
1 0 External loopback. Turns on the
external loopback mode to signal the
PHY to loop back transmit packets.
1 1 Full Duplex mode. De-couples
transmit and receive blocks to allow
full duplex operation without
collisions.
0 - EARLY TRANSMIT ENABLE: When set,
the transmitter operates in early transmit
mode.
74 - TRANSMIT STATUS
Reset Value: 0000000000000
The transmit status register reports events that
occur on the media at the end of packet
transmission. All bits are cleared prior to
transmission of a packet and are set as
needed. This register may be read when a
transmit underrun occurs (before the TXUGO
bit is set), otherwise it should only be
accessed for test purposes.
31 through 13: Unused.
12 through 8 - COLLISION COUNT: These
bits contain the number of collisions detected
while attempting to transmit the current
packet. Bit 12 also indicates transmit abort for
excessive collisions.
7 - DEFERRING: This bit is set when the
interframe gap state machine is deferring. If
the PHY has asserted the collision line as a
result of jabber, this bit will stay set indicating
the jabber condition. Always returns 0.
6 - OUT OF WINDOW COLLISION: This bit is set
if a collision is detected more than one slot time
after the start of transmission. Transmission is
aborted under these conditions.
5 - COLLISION DETECT HEARTBEAT: This bit is
set to a '1' during transmission of each packet. It
is set to '0' if a collision is detected within 36 bit
times of the end of each packet transmission. If
no collision is detected within this window, it
remains '1'. This bit always returns zero in full
duplex mode.
4 - UNDERRUN: This bit is set when the transmit
DMA is unable to supply the transmitter enough
data to maintain frame transmission.
3 - CARRIER SENSE LOST: This bit is set if the
carrier is lost during packet transmission. Carrier
sense is monitored from its rising edge at the start
of the outgoing frames echo. Transmission is not
aborted upon loss of carrier. This bit will always
return zero in full duplex mode.
2 - TRANSMITTED WITH COLLISIONS: When
set, this bit indicates the frame collided at least
once with another frame on the network. It is not
set for either out-of-window collisions or
excessive collision aborts.
1 - NON-DEFERRED TRANSMISSION: This bit is
set if the frame was transmitted successfully
without deferring. A deferred transmission can
only occur the first time an attempt is made to
send a packet. Collisions are not deferred
transmissions.
0 - PACKET TRANSMITTED: This bit is set to
indicate transmission of a packet without
excessive collisions or abort.
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