Specifications

DP83848Q-Q1
SNLS341C –MARCH 2011–REVISED MARCH 2015 www.ti.com
5.6.1 Register Definition
In the register definitions under the ‘Default’ heading, the following definitions hold true:
• RW = Read Write access
• SC = Register sets on event occurrence and Self-Clears when event ends
• RW/SC = ReadWrite access/Self Clearing bit
• RO = Read Only access
• COR = Clear On Read
• RO/COR = Read Only, Clear On Read
• RO/P = Read Only, Permanently set to a default value
• LL = Latched Low and held until read, based upon the occurrence of the corresponding event
• LH = Latched High and held until read, based upon the occurrence of the corresponding event
5.6.1.1 Basic Mode Control Register (BMCR)
Table 5-9. Basic Mode Control Register (BMCR), address 0x00h
BIT BIT NAME DEFAULT DESCRIPTION
15 RESET 0, RW/SC Reset:
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.
14 LOOPBACK 0, RW 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
µs “dead time” before any valid data will appear at the MII receive outputs.
13 SPEED SELECTION Strap, RW Speed Select:
When auto-negotiation is disabled writing to this bit allows the port speed to be selected.
1 = 100 Mb/s.
0 = 10 Mb/s.
12 AUTO-NEGOTIATION Strap, RW Auto-Negotiation Enable:
ENABLE
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.
11 POWER DOWN 0, RW 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.
10 ISOLATE 0, RW Isolate:
1 = Isolates the Port from the MII with the exception of the serial management.
0 = Normal operation.
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