ICS1890
Functional Blocks
Media Independent Interface (MII) Overview
The MII consists of a data interface, basic register set, and a
serial management interface to the register set.
The data interface is a nibble wide transmit and receive data
interface between the MAC and PHY devices. The interface
supports data transfers at 25 MHz for 100Base-T and 2.5 MHz
for 10Base-T.
The register set consists of basic and extended standard
registers as well as vendor specific registers. There are two
basic registers, a control register to handle basic device
configuration, and a status register to report basic device
abilities and status. The standard extended registers provide
access to an Organizationally Unique Identifier and Auto-
Negotiation functionality.
The
ICS1890
also provides vendor specific registers that
enhance the device operation. Among these is the QuickPoll
Detailed Status register which provides a comprehensive set
of real-time device information with only single register access.
The
ICS1890
auto-negotiation logic is designed to operate
with legacy 10Base-T networks or newer systems with multiple
connection technology options. When operating with a legacy
10Base-T remote partner, the
ICS1890
will select the 10Base-
T operating mode transparently to the remote partner thus
allowing the preservation of existing legacy network structures
without management intervention.
Auto-negotiation is accomplished using a physical signaling
scheme that is transparent at the packet and higher level
protocols. This scheme builds upon the 10Base-T link test
pulse sequence by using a burst of pulses to signal
configuration information between the two devices.
The Fast Link Pulse Bursts are simultaneously exchanged by
both nodes on a link segment the local node encodes the data
from the Auto-negotiation Advertisement Register (register
4) into the FLP Bursts it transmits. The data received from the
link partners FLP Bursts is placed into the Auto-Negotiation
Link Partner Ability Register (register 5). When Auto-Negotiation
is complete (1:5=1 or 17:4=1), the highest priority technology
from the following table that is common in the two registers is
automatically selected as the operating mode.
Priority Resolution Table
Highest Priority Listed first.
1)
2)
3)
4)
5)
8
100Base-TX Full Duplex
100Base-T4
100Base-TX
10Base-T Full Duplex
10Base-T
Auto-Negotiation
The auto-negotiation logic of the
ICS1890
has three main
purposes. Firstly, to determine the capabilities of the remote
partner (device at the other end of the cable). Secondly, to
advertise its own capabilities to the remote partner. And thirdly,
to establish a connection with the remote partner using the
highest performance common connection technology.
ICS [ INTEGRATED CIRCUIT SYSTEMS ]
