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Datasheet 29
Networking Silicon — 82555
7.2.1.2 Register 1: Status Register Bit Definitions
11 Power-Down This bit sets the 82555 into a low power mode.
1 = Power-down enabled
0 = Power-down disabled (normal operation)
0RW
10 Isolate This bit allows the 82555 to electrically isolate the Media
Independent Interface. When the MII is isolated, the
82555 does not respond to TXD[3:0], TXEN, and TXERR
input signals. Also, the 82555 presents high impedance
on its TXC, RXC, RXDV, RXERR, RXD[3:0], COL, and
CRS output signals. In the TX mode, the 82555 responds
to management transactions.
1 = Electrically isolate MII
0 = Normal operation
0RW
9 Restart Auto-
Negotiation
This bit restarts the Auto-Negotiation process and is self-
clearing.
1 = Restart Auto-Negotiation process
0 = Normal operation
0RW
SC
8 Duplex Mode This bit controls the duplex mode when Auto-Negotiation
is disabled. If the 82555 reports that it is only able to
operate in one duplex mode, the value of this bit shall
correspond to the mode which the 82555 can operate.
When the 82555 is placed in Loopback mode, the
behavior of the PHY shall not be affected by the status of
this bit, bit 8.
1 = Full Duplex
0 = Half Duplex
0RW
7 Collision Test This bit will force a collision in response to the assertion
of the transmit enable signal.
1 = Force COL
0 = Do not force COL
0RW
6:0 Reserved These bits are reserved and should be set to 0000000b. 0 RW
Bit(s) Name Description Default R/W
15 100BASE-T4 1 = 82555 able to perform 100BASE-T4
0 = 82555 not able to perform 100BASE-T4
-- RO
P
14 100BASE-TX Full
Duplex
1 = 82555 able to perform full duplex 100BASE-TX
0 = 82555 not able to perform full duplex in repeater
mode
-- RO
P
13 100 Mbps Half
Duplex
1 = 82555 able to perform half duplex 100BASE-TX
0 = 82555 not able to perform 100BASE-TX
-- RO
P
12 10 Mbps Full
Duplex
1 = 82555 able to operate at 10 Mbps in full duplex
mode
0 = 82555 not able to operate in full duplex mode in
10BASE-T
-- RO
P
11 10 Mbps Half
Duplex
1 = 82555 able to operate at 10 Mbps in half duplex
mode
0 = 82555 not able to operate in 10BASE-T
-- RO
P
10:7 Reserved These bits are reserved and should be set to 0000b. 0 RO
Bit(s) Name Description Default R/W