AM79C978A AMD [Advanced Micro Devices], AM79C978A Datasheet - Page 148

• Manufacturer Part Number: AM79C978A
• Description: Single-Chip 1/10 Mbps PCI Home Networking Controller
• Manufacturer: AMD [Advanced Micro Devices]

LED1 register is disabled. Writes to those registers will
be ignored.
Note: Bits 15-0 in this register are programmable
through the EEPROM.
Bit
31-16 RES
15
14
148
LEDOUT
LEDPOL
Name
This bit indicates the current
Reserved locations. Written as
zeros and read as undefined.
(non-stretched) value of the
LED output pin. A value of 1 in
this bit indicates that the OR of
the enabled signals is true.
The logical value of the LEDOUT
status signal is determined by the
settings of the individual Status
Enable bits of the LED register
(bits 8 and 6-0).
This bit is always read accessi-
ble. This bit is read only; writes
have no effect. LEDOUT is unaf-
fected by H_RESET, S_RESET,
or STOP.
LED Polarity. When this bit has
the value 0, then the LED pin
will be driven to a LOW level
whenever the OR of the enabled
signals is true, and the LED pin
will be disabled and allowed to
float high whenever the OR of
the enabled signals is false (i.e.,
the LED output will be an Open
Drain output and the output val-
ue will be the inverse of the
LEDOUT status bit).
When this bit has the value 1,
then the LED pin will be driven to
a HIGH level whenever the OR of
the enabled signals is true, and
the LED pin will be driven to a
LOW level whenever the OR of
the enabled signals is false (i.e.,
the LED output will be a Totem
Pole output and the output value
will be the same polarity as the
LEDOUT status bit).
The setting of this bit will not ef-
fect the polarity of the LEDOUT
bit for this register.
This bit is always read/write ac-
cessible. LEDPOL is cleared by
Description
Am79C978A
13
12
11-10 RES
9
8
LEDDIS
100E
MPSE
FDLSE
LED Disable. This bit is used to
Reserved locations. Written and
Full-Duplex Link Status Enable.
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
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.
This bit is always read/write ac-
cessible. LEDDIS is cleared by
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
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 Am79C978A controller
is operating at 100 Mbps mode.
This bit is always read/write ac-
cessible. 100E is cleared by
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
read as zeros.
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 Packet
mode is enabled and a Magic
Packet frame is detected on the
network.
This bit is always read/write ac-
cessible. MPSE is cleared by
H_RESET and is not affected
by S_RESET or setting the
STOP bit.
Indicates the Full-Duplex Link
Test Status. When this bit is
set, a value of 1 is passed to
the LEDOUT signal when the
Am79C978A controller is func-
tioning in a Link Pass state and
full-duplex operation
abled. When the Am79C978A
controller is not functioning in a
Link Pass state with full-duplex
is en-