DP83858VF datasheet(17/37 Pages) NSC

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4.3 Configuration Register (CONFIG)

Page 0

Address 0h

Page 1

Address 0h

Bit

Bit Name

Access

Bit Description

D15 - D6

reserved

—

For compatibility with future enhanced versions these bits must be written as zero.

They are undeﬁned when read.

REGEN_PRE

r/w

Regenerate Preamble: This bit may be used to overwrite/change the repeater mode

(TX or T4) that is set by the MODE[1:0] pins at power-up. If MODE[1:0] is 1, 1 then

this bit is set, otherwise this bit will be zero.

The time when the preamble is regenerated depends upon the type of the PHY (ei-

ther TX or T4 PHYs) attached to the repeater. For a TX PHY, preamble is regenerat-

ed approximately 4 clocks (RXC) after the /IR_ACTIVE assertion, and for a T4 PHY,

preamble is regenerated approximately 12 clocks after the /IR_ACTIVE assertion.

MGTEN

r/w

Management Enable: This bit enables all the management counters.

Management Counters disabled (default).

Management Counters enabled.

Note: The management counters can only be reliably written to when they are dis-

abled.

COL_LIMIT32

r/w

This bit conﬁgures the collision limit for Auto-Partitioning algorithm:

Consecutive Collision Limit set to 64 consecutive collisions (default). A port will

be partitioned on the 65th consecutive collision.

Consecutive Collision Limit set to 32 consecutive collisions. A port will be parti-

tioned on the 33rd consecutive collision.

DIS_PART

r/w

This bit disables the Auto-Partitioning algorithm:

Auto-Partitioning is not disabled (default).

Auto-Partitioning is disabled.

PHY_ACCESS

r/w

This bit allows the management agent to access the DP83840A PHY chip’s register

via the MII serial protocol.

PHY access disabled (default).

PHY register access enabled.

Note: When in PHY_access mode, RDIO will be driven by the DP83858 during the

read phase for all read commands. This is to allow the DP83840A Physical Layer de-

vices to pass their data through their local DP83858. While in this mode, contention

will result (on the RDIO line) if any device other than this DP83858 or the DP83840A

Physical Layer devices are accessed.

RST_RSM

r/w

Setting this bit holds the Repeater State Machines in reset. The management event

ﬂags and counters are unaffected by this bit. Setting this bit while a reception is in

progress may truncate the packet.

DP83858 in normal operation (default).

DP83858 held in reset.

DP83858VF Datasheet(PDF) 17 Page - National Semiconductor (TI)

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