DP83846AVHG63SN National Semiconductor, DP83846AVHG63SN Datasheet - Page 30

• Manufacturer Part Number: DP83846AVHG63SN
• Manufacturer: National Semiconductor

Specifications of DP83846AVHG63SN

• Lead Free Status / RoHS Status: Not Compliant

Bit
6:0
15
14
13
12
11
10
9
8
7
Auto-Negotiation
Speed Selection Strap, RW Speed Select:
Restart Auto-
Duplex Mode
Collision Test
Power Down
RESERVED
Negotiation
Bit Name
Loopback
Enable
Isolate
Reset
Strap, RW Auto-Negotiation Enable:
Strap, RW Duplex Mode:
Table 7. Basic Mode Control Register (BMCR), Address 0x00
0, RW/SC Restart Auto-Negotiation:
0, RW/SC Reset:
Default
0, RW
0, RW
0, RW
0, RW
0, RO
1 = Initiate software Reset / Reset in Process.
0 = Normal operation.
This bit, which is self-clearing, returns a value of one until the reset process is
complete. The configuration is re-strapped.
Loopback:
1 = Loopback enabled.
0 = Normal operation.
The loopback function enables MII transmit data to be routed to the MII receive
data path.
Setting this bit may cause the descrambler to lose synchronization and produce a
500 s “dead time” before any valid data will appear at the MII receive outputs.
When auto-negotiation is disabled writing to this bit allows the port speed to be se-
lected.
1 = 100 Mb/s.
0 = 10 Mb/s.
Strap controls initial value at reset.
1 = Auto-Negotiation Enabled - bits 8 and 13 of this register are ignored when this
bit is set.
0 = Auto-Negotiation Disabled - bits 8 and 13 determine the port speed and duplex
mode.
Power Down:
1 = Power down.
0 = Normal operation.
Setting this bit powers down the PHY. Only the register block is enabled during a
power down condition.
Isolate:
1 = Isolates the Port from the MII with the exception of the serial management.
0 = Normal operation.
1 = Restart Auto-Negotiation. Re-initiates the Auto-Negotiation process. If Auto-
Negotiation is disabled (bit 12 = 0), this bit is ignored. This bit is self-clearing and
will return a value of 1 until Auto-Negotiation is initiated, whereupon it will self-
clear. Operation of the Auto-Negotiation process is not affected by the manage-
ment entity clearing this bit.
0 = Normal operation.
When auto-negotiation is disabled writing to this bit allows the port Duplex capa-
bility to be selected.
1 = Full Duplex operation.
0 = Half Duplex operation.
Collision Test:
1 = Collision test enabled.
0 = Normal operation.
When set, this bit will cause the COL signal to be asserted in response to the as-
sertion of TX_EN within 512-bit times. The COL signal will be de-asserted within
4-bit times in response to the de-assertion of TX_EN.
RESERVED: Write ignored, read as 0.
30
Description
www.national.com