5228-DS04-R datasheet(70/100 Pages) BOARDCOM

70 / 100 page

BCM5228

Data Sheet

7/12/04

Broa d c om Co rp o r a t i o n

Page 58

10BASE-T Auxiliary Error and General Status Register

Document

5228-DS09-405-R

All Error bits in the Auxiliary Error and General Status register are read-only and are latched high. When certain types of

errors occur in the BCM5228, one or more corresponding error bits become 1. They remain so until the register is read, or

until a chip reset occurs. All such errors necessarily result in data errors, and are indicated by a high value on the RXER

output pin at the time the error occurs.

MDIX Status. This bit, when read as a 1, indicates that the MDI TD± and RD± signals for the BCM5228 have been

swapped. The cause for this is one of the following:

•

the MDIX Swap bit was manually set to a 1, or

•

the HP Auto-MDIX function is enabled and the BCM5228 has detected an MDI cross-over cable.

MDIX Manual Swap. When this bit is set to a 1, the MDI TD± and RD± signals for the BCM5228 are forced into being

swapped.

HP Auto-MDIX Disable. When this bit is set to a 1, the HP Auto-MDIX function is disabled in the BCM5228.

Manchester Code Error. Indicates that a Manchester code violation was received. This bit is only valid during 10BASE-T

operation.

End-of-Frame Error. Indicates that the end-of-frame (EOF) sequence was improperly received, or not received at all. This

error bit is only valid during 10BASE-T operation.

Auto-Negotiation Indication. A read-only bit that indicates whether auto-negotiation has been enabled or disabled on the

BCM5228. A combination of a 1 in bit 12 of the Control register and a logic 1 on the ANEN input pin is required to enable

auto-negotiation. When auto-negotiation is disabled, bit 15 of the Auxiliary Mode register returns a 0. At all other times, it

returns a 1.

Force 100/10 Indication. A read-only bit that returns a value of 0 when one of following two cases is true:

•

The ANEN pin is low AND the F100 pin is low, or

•

Bit 12 of the Control register has been written 0 AND bit 13 of the Control register has been written 0.

When bit 2 of the Auxiliary Control register is 0, the speed of the chip is 10BASE-T. In all other cases, either the speed is

not forced (auto-negotiation is enabled), or the speed is forced to 100BASE-X.

Speed Indication. A read-only bit that shows the true current operation speed of the BCM5228. A 1 bit indicates 100BASE-

X operation, while a 0 indicates 10BASE-T. While the auto-negotiation exchange is performed, the BCM5228 is always

operating at 10BASE-T speed.

Auto-Negotiation Indication

1 = Auto-negotiation activated

0 = Speed forced manually

Force 100/10 Indication

1 = Speed forced to 100BASE-X

0 = Speed forced to 10BASE-T

Speed Indication

1 = 100BASE-X

0 = 10BASE-T

Full-Duplex Indication

1 = Full-duplex active

0 = Full-duplex not active

a. Preserve existing values of reserved bits by completing a “Read/Modify Write.”

Table 36: 10BASE-T Auxiliary Error and General Status Register (Address 28d, 1Ch)

Note: R/W = Read/Write, RO = Read Only, SC = Self Clear, LL = Latched Low, LH = Latched High, LL and LH Clear

after read operation.

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