AM79C971VCW Advanced Micro Devices, AM79C971VCW Datasheet - Page 152

• Manufacturer Part Number: AM79C971VCW
• Description: PCnet-FAST Single-Chip Full-Duplex 10/100 Mbps Ethernet Controller for PCI Local Bus
• Manufacturer: Advanced Micro Devices

BCR4: LED0 Status
BCR4 controls the function(s) that the LED0 pin dis-
plays. Multiple functions can be simultaneously en-
abled on this LED pin. The LED display will indicate the
logical OR of the enabled functions. BCR4 defaults to
Link Status (LNKST) with pulse stretcher enabled
(PSE = 1) and is fully programmable.
Note: When LEDPE (BCR2, bit 12) is set to 1, pro-
gramming of the LED0 Status register is enabled.
When LEDPE is cleared to 0, programming of the
LED0 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
152
PORTSEL[1:0]
LEDOUT
LEDPOL
Name
XX
XX
XX
00
01
10
11
Reserved locations. Written as
zeros and read as undefined.
This bit indicates the current
(non-stretched) value of the LED
output pin. A value of 1 in this bit
indicates that the OR of the en-
abled signals is true.
LED Polarity. When this bit has
the value 0, then the LED pin will
be driven to a LOW level whenev-
er the OR of the enabled signals
is true, and the LED pin will be
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).
Read accessible always. This bit
is read only; writes have no ef-
fect. LEDOUT is unaffected by
H_RESET, S_RESET, or STOP.
Description
(BCR2[1])
ASEL
1
1
1
0
0
0
0
Table 31. Network Port Configuration
P R E L I M I N A R Y
Am79C971
(of 10BASE-T)
Link Status
Don’t Care
Don’t Care
Don’t Care
Don’t Care
Don’t Care
Pass
Fail
13
LEDDIS
(BCR32[14])
Don’t Care
Don’t Care
Don’t Care
Don’t Care
MII Status
LED Disable. This bit is used to
disabled and allowed to float high
whenever the OR of the enabled
signals is false (i.e., the LED out-
put will be an Open Drain output
and the output value 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.
Read/Write accessible always.
LEDPOL is cleared by 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.
Read/Write accessible always.
LEDDIS is cleared by H_RESET
and is not affected by S_RESET
or setting the STOP bit.
0
0
1
10BASE-T
10BASE-T
Network
GPSI
Port
AUI
AUI
MII
MII