ICS1893 datasheet(79/153 Pages) RENESAS

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Chapter 8

Management Register Set

ICS1893 Rev C 6/6/00

June, 2000

ICS1893 - Release

8.6.5.2

Technology Ability Field: Software Mode

In Software mode (that is, the HW/SW pin is logic one), these TAF bits are Command Override Write bits.

The default value of these bits depends on the signal level on the HW/SW pin and whether the

Auto-Negotiation sublayer is enabled.

In Software mode, with the Auto-Negotiation Enable bit (bit 0.12) set to logic:

• Zero (that is, disabled), the ICS1893 does not execute the auto-negotiation process. Upon completion of

the initialization sequence, the ICS1893 proceeds to the Idle state and begins transmitting IDLES. Two

Control Register bits – the Data Rate Select bit (bit 0.13) and the Duplex Select bit (bit 0.8) – determine

the technology mode that the ICS1893 uses for data transmission and reception. In this mode, the

values of the TAF bits (bits 4.8:5) are undefined.

• One (that is, enabled), the ICS1893 executes the auto-negotiation process and advertises its capabilities

to the remote link partner. The TAF bits (bits 4.8:5) determine the capabilities that the ICS1893

advertises to its remote link partner. For the ICS1893, all of these bits 4.8:5 are set to logic one,

indicating the ability of the ICS1893 to provide these technologies.

Note:

The ICS1893 does not alter the value of the Status Register bits based on the TAF bits in register

4, as the ISO/IEC definitions for the Status Register bits require these bits to indicate all the

capabilities of the ICS1893.

In this mode, an STA can alter the default TAF bit settings, 4.12:5, and subsequently issue an

Auto-Negotiation Restart.

8.6.6

Selector Field (Bits 4.4:0)

When its Auto-Negotiation Sublayer is enabled, the ICS1893 transmits its link capabilities to its remote Link

Partner during the auto-negotiation process. The Selector Field is transmitted based on the value of bits

4.4:0. These bits indicate to the remote link partner the type of message being sent during the

auto-negotiation process. The ICS1893 supports IEEE Std 802.3, represented by a value of 00001b in bits

4.4:0. The ISO/IEC 8802-3 standard defines the Selector Field technologies in Annex 28A.

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