ICS1893 Datasheet, PDF (78/152 Pages) Integrated Circuit Systems – 3.3-V 10Base-T/100Base-TX Integrated PHYceiver™

ICS1893 Data Sheet - Release
Chapter 8 Management Register Set
8.6.5 Technology Ability Field (bits 4.9:5)
When its Auto-Negotiation sublayer is enabled, the ICS1893 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 ICS1893 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 ICS1893 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 ICS1893, 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
Register Override bit) is logic:
• Zero, the ICS1893 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 ICS1893 operating mode.
Bit 4.9 is always logic zero, indicating that the ICS1893 cannot support 100Base-T4 operations.
8.6.5.1 Technology Ability Field: Hardware Mode
When the ICS1893 is operating in hardware mode (that is, the HW/SW pin is logic zero), these TAF bits are
Read-Only 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 hardware mode, with the ANSEL pin pulled:
• Low to a disabled state, the ICS1893 does not execute the auto-negotiation process. Upon completion
of the initialization sequence, the ICS1893 proceeds to the idle state and begins ‘sending idles’
according to the technology mode selected by the 10/100SEL pin and the DPXSEL pin. In this mode, the
values of the TAF bits (bits 4.8:5) are undefined.
• High to an enabled state, the ICS1893 executes the auto-negotiation process and advertises its
capabilities to the remote link partner immediately following reset. The 10/100SEL and DPXSEL input
pins determine the single capability that the ICS1893 advertises. The ICS1893 updates the
Auto-Negotiation Advertisement Register TAF field to indicate the selection made by these pins. The
ICS1893 sets only one of these four bits to logic one. The other three bits are a logic zero.
Note: The ICS1893 does not alter the value of the Status Register bits. Although the ICS1893 is
advertising only one technology, the ISO/IEC definitions for the Status Register bits require
these bits to indicate all the capabilities of the ICS1893.
ICS1893 Rev C 6/6/00
Copyright © 2000, Integrated Circuit Systems, Inc.
All rights reserved.
78
June, 2000