Am79C978A
153
by S_RESET or setting the
STOP bit.
5
RCVME
Receive Match Status Enable.
When this bit is set, a value of 1 is
passed to the LEDOUT bit in this
register when there is receive ac-
tivity on the network that has
passed the address match func-
tion for this node. All address
matching modes are included:
physical, logical filtering, broad-
cast, and promiscuous.
This bit is always read/write ac-
cessible. RCVME is cleared by
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
4
XMTE
Transmit Status Enable. When
this bit is set, a value of 1 is
passed to the LEDOUT bit in this
register when there is transmit
activity on the network.
This bit is always read/write ac-
cessible. XMTE is set to 1 by
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
3
POWER
Power. When this bit is set to 1,
the device is operating in HIGH
power mode.
2
RCVE
Receive Status Enable. When
this bit is set, a value of 1 is
passed to the LEDOUT bit in this
register when there is receive
activity on the network.
This bit is always read/write ac-
cessible. RCVE is cleared by
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
1
SPEED
Speed. When this bit is set to 1,
the device is operating in HIGH
speed mode.
0
COLE
Collision Status Enable. When
this bit is set, a value of 1 is
passed to the LEDOUT bit in this
register when there is collision
activity on the network.
This bit is always read/write ac-
cessible. COLE is cleared by
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
BCR9: Full-Duplex Control
Note:
Bits 15-0 in this register are programmable
through the EEPROM.
Bit
Name
Description
31-3
RES
Reserved locations. Written as
zeros and read as undefined.
2
FDRPAD
Full-Duplex Runt Packet Accept
Disable. When FDRPAD is set to
1 and full-duplex mode is en-
abled, the Am79C978A controller
will only receive frames that meet
the minimum Ethernet frame
length of 64 bytes. Receive DMA
will not start until at least 64 bytes
or a complete frame have been
received. By default, FDRPAD is
cleared to 0. The Am79C978A
controller will accept any length
frame and receive DMA will start
according to the programming of
the receive FIFO watermark.
Note that there should not be any
runt packets in a full-duplex net-
work, since the main cause for
runt packets is a network collision
and there are no collisions in a
full-duplex network.
This bit is always read/write ac-
cessible. FDRPAD is cleared
by H_RESET and is not affect-
ed by S_RESET or by setting
the STOP bit.
1
RES
Reserved locations. Written as
zeros and read as undefined.
0
FDEN
Full-Duplex Enable. FDEN con-
trols whether full-duplex opera-
tion is enabled. When FDEN is
cleared and the Auto-Negotiation
is disabled, full-duplex operation
is
not
enabled
Am79C978A controller will al-
ways operate in half-duplex
mode. When FDEN is set, the
Am79C978A controller will oper-
ate in full-duplex mode.
and
the