
Am79C971
161
P R E L I M I N A R Y
13
LEDDIS
LED Disable. This bit is used to
disable the LED output. When
LEDDIS has the value 1, then the
LED output will always be dis-
abled. When LEDDIS has the val-
ue 0, then the LED output value
will be governed by the LEDOUT
and LEDPOL values.
Read/Write accessible always.
LEDDIS is cleared by H_RESET
and is not affected by S_RESET
or setting the STOP bit.
12
100E
100 Mbps Enable. When this bit
is set to 1, a value of 1 is passed
to the LEDOUT bit in this register
when the Am79C971 controller is
operating at 100 Mbps mode. The
indication is valid with both the in-
ternal and external PHYs.
Read/Write accessible always.
100E is cleared by H_RESET
and is not affected by S_RESET
or setting the STOP bit.
11
MIISE
Media Independent Interface Se-
lected Enable. Indicates when the
MII interface is selected. This will
be set when either the Manage-
ment Port State Machine is se-
lecting the MII or when ASEL
(BCR2, bit1) is disabled and
PORTSEL (CSR15, bits 8-7) se-
lects the MII. This could control
relays to switch in and out appro-
priate filters or could control an
external PHY when sharing an
RJ45 connector.
Read/Write accessible always.
MIISE is cleared by H_RESET
and is not affected by S_RESET
or setting the STOP bit.
10
DXCVRCTL DXCVR Control. When the AUI
interface is the active network
port, DXCVRCTL controls the as-
sertion of the LED3 output. The
polarity of the asserted state is
controlled by the LEDPOL bit
(BCR4, bit 14). The LED3 pin can
be used to control a DC-to-DC
converter in applications that
want to connect a 10BASE2
MAU, as well as a standard DB15
AUI connector to the Am79C971
AUI port. When DXCVRCTL is
set to 1, the LED3 output will be
asserted. This could be used to
enable a DC-to-DC converter for
10BASE2 MAUs (assuming the
enable input of the DC-to-DC
converter is active high and LED-
POL is cleared to 0). When DX-
CVRCTL is cleared to 0, the
LED3 output will be deasserted.
This would power down the DC-
to-DC
converter.
10BASE-T interface is the active
network port, the DXCVR output
is always deasserted.
When
the
Read/Write accessible always.
DXCVRCTL
is
H_RESET and is unaffected by
S_RESET or by setting the STOP
bit.
cleared
by
9
MPSE
Magic Packet Status Enable.
When this bit is set to 1, a value of
1 is passed to the LEDOUT bit in
this register when magic frame
mode is enabled and a magic
frame is detected on the network.
Read/Write accessible always.
MPSE is cleared by H_RESET
and is not affected by S_RESET
or setting the STOP bit.
8
FDLSE
Full-Duplex Link Status Enable.
Indicates the Full-Duplex Link
Test Status. When this bit is set,
a value of 1 is passed to the LED-
OUT signal when the Am79C971
controller is functioning in a Link
Pass state and full-duplex opera-
tion is enabled. When the
Am79C971 controller is not func-
tioning in a Link Pass state with
full-duplex operation being en-
abled, a value of 0 is passed to
the LEDOUT signal.
When the 10BASE-T port is ac-
tive, a value of 1 is passed to the
LEDOUT signal whenever the
Link Test Function (described in
the T-MAU section) detects a
Link Pass state and the FDEN
(BCR9, bit 0) bit is set. When the
AUI port is active, a value of 1 is
passed to the LEDOUT signal
whenever full-duplex operation
on the AUI port is enabled (both