ICS1893AF datasheet(74/137 Pages) RENESAS

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ICS1893AF, Rev D 10/26/04

October, 2004

Chapter 8

Management Register Set

ICS1893AF Data Sheet - Release

8.6.5

Technology Ability Field (bits 4.9:5)

When its Auto-Negotiation sublayer is enabled, the ICS1893AF transmits its link capabilities to its remote

link partner during the auto-negotiation process. The Technology Ability Field (TAF) bits 4.12:5 determine

the specific abilities that the ICS1893AF advertises. The ISO/IEC specification defines the TAF

technologies in Annex 28B.

The ISO/IEC specification reserves bits 4.12:10 for future use. When each of these reserved bits is:

• Read by an STA, the ICS1893AF returns a logic zero

• Written to by an STA, the STA must use the default value specified in this data sheet

ICS uses some reserved bits to invoke auxiliary functions. To ensure proper operation of the ICS1893AF,

an STA must maintain the default value of these bits. Therefore, ICS recommends that an STA always write

the default value of any reserved bits during all management register write operations.

Reserved bits 4.12:10 are Command Override Write (CW) bits. Whenever bit 16.15 (the Command

• Zero, the ICS1893AF isolates all STA writes to CW bits, including bits 4.12:10.

• One, an STA can modify the value of bits 4.12:10

Each of the bits 4.9:5 in the TAF represent a specific technology capability. When one of these bits is logic:

• Zero, it indicates to the remote link partner that the local device cannot support the technology

represented by the bit.

• One, it indicates to the remote link partner that the local device can support the technology.

With the exception of bit 4.9, the default settings of the TAF bits depend on the ICS1893AF operating

mode. Bit 4.9 is always logic zero, indicating that the ICS1893AF cannot support 100Base-T4 operations.

The 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.

With the Auto-Negotiation Enable bit (bit 0.12) set to logic:

• Zero (that is, disabled), the ICS1893AF does not execute the auto-negotiation process. Upon completion

of the initialization sequence, the ICS1893AF 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 ICS1893AF 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 ICS1893AF 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

ICS1893AF advertises to its remote link partner. For the ICS1893AF, all of these bits 4.8:5 are set to

logic one, indicating the ability of the ICS1893AF to provide these technologies.

Note:

The ICS1893AF does not alter the value of the Status Register bits based on the TAF bits in

capabilities of the ICS1893AF.

The STA can alter the default TAF bit settings, 4.12:5, and subsequently issue an Auto-Negotiation

Restart.

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