ST802RT1B datasheet(36/58 Pages) STMICROELECTRONICS

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Registers and descriptors description

ST802RT1A, ST802RT1B

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Doc ID 17049 Rev 1

HCD 10BaseT: Bits 15:11 of the auxiliary PHY register are five read-only bits that report the

highest common denominator (HCD) result of the auto-negotiation process. Immediately

upon entering the link pass state after each reset or restart auto-negotiation, only one of

these five bits will be a “1”. The link pass state is identified by a “1” in bit 6 or 7 of this

ST802RT1x is reset. Note that for their intended application, these bits uniquely identify the

HCD only after the first link pass after reset or restart of auto-negotiation. On later link fault

and subsequent re-negotiations, if the ability of the link partner is different, more than one of

the above bits may be active. These bits are only set for full auto-negotiation handshake,

and not for parallel detection of forced speed modes. Note that bit 14, HCD_T4, is never set

in the ST802RT1x.

Reserved: Ignore when read.

Restart auto-negotiation: A self-clearing bit that allows the auto-negotiation process to be

restarted, regardless of the current status of the state machine. For this bit to work, auto-

negotiation must be enabled. Writing a “1” to this bit restarts auto-negotiation. Since the bit

is self-clearing, it always returns a “0” when read. The operation of this bit is identical to bit 9

of the control register.

Auto-negotiation complete: This read-only bit returns a “1” after the auto-negotiation

process has been completed. It remains “1” until the auto-negotiation is restarted, a link fault

occurs, or the chip is reset. If auto-negotiation is disabled, or the process is still in progress,

the bit returns a “0”.

Auto-negotiation ack: This read-only bit is set to “1” when the arbitrator state machine

exits the acknowledged detect state. It remains high until the auto-negotiation process is

restarted, or the ST802RT1x is reset.

Auto-negotiation ability: This read-only bit returns a “1” when the auto-negotiation state

machine is in the ability detect state. It enters this state a specified time period after the

auto-negotiation process begins, and exits after the first FLP burst or link pulses are

detected from the link partner. This bit returns a “0” any time the auto-negotiation state

machine is not in the ability detect state.

Super isolate: Writing a “1” to this bit places the ST802RT1x into the super isolate mode.

Similar to the isolate mode, all MII inputs are ignored, and all MII outputs are tri-stated.

Additionally, all link pulses are suppressed. This allows the ST802RT1x to coexist with

another PHY on the same adapter card, with only one being activated at any time.

Table 29.

RN1F [0d31, 0x1F]: Shadow registers enable register

Bit

Bit name

Description

Default

Type

15:8

RESERVED

NOT USED

00000000b

Shadow

Registers Enable

1 -> Shadow registers enabled

0 -> Normal operation

When this bit is set, registers at addresses 1B are masked

by correspondent shadow registers

Self-clearing functionality added to this bit when shadow

registers are enabled

0RW

6:0

RESERVED

Not used

0000000b

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