ICS1893AFILFT datasheet(25/137 Pages) RENESAS

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Chapter 6

Interface Overviews

ICS1893AF, Rev. D 10/26/04

October, 2004

ICS1893AF Data Sheet - Release

6.1

MII Data Interface

The ICS1893AF’s MAC Interface is the Medium Independent Interface (MII) operating at either 10 Mbps or

100 Mbps. The ICS1893AF MAC/Repeater Interface is configured for the MII Data Interface mode, data is

transferred between the PHY and the MAC as framed, 4-bit parallel nibbles. In addition, the interface also

provides status and control signals to synchronize the transfers.

The ICS1893AF provides a full complement of the ISO/IEC-specified MII signals. Its MII has both a transmit

and a receive data path to synchronously exchange 4 bits of data (that is, nibbles).

• The ICS1893AF’s MII transmit data path includes the following:

– A data nibble, TXD[3:0]

– A transmit data clock to synchronize transfers, TXCLK

– A transmit enable signal, TXEN

– A transmit error signal, TXER

• The ICS1893AF’s MII receive data path includes the following:

– A separate data nibble, RXD[3:0]

– A receive data clock to synchronize transfers, RXCLK

– A receive data valid signal, RXDV

– A receive error signal, RXER

Both the MII transmit clock and the MII receive clock are provided to the MAC/Reconciliation sublayer by

the ICS1893AF (that is, the ICS1893AF sources the TXCLK and RXCLK signals to the MAC/repeater).

Clause 22 also defines as part of the MII a Carrier Sense signal (CRS) and a Collision Detect signal (COL).

The ICS1893AF is fully compliant with these definitions and sources both of these signals to the

MAC/repeater. When operating in:

• Half-duplex mode, the ICS1893AF asserts the Carrier Sense signal when data is being either transmitted

or received. While operating in half-duplex mode, the ICS1893AF also asserts its Collision Detect signal

to indicate that data is being received while a transmission is in progress.

• Full-duplex mode, the ICS1893AF asserts the Carrier Sense signal only when receiving data and forces

the Collision Detect signal to remain inactive.

As mentioned in Section 5.1.1.3, “Hot Insertion”, the ICS1893AF design allows hot insertion of its MII. That

is, it is possible to connect its MII to a MAC when power is already applied to the MAC. To support this

functionality, the ICS1893AF isolates its MII signals and tri-states the signals on all Twisted-Pair Transmit

pins (TP_TXP and TP_TXN) during a power-on reset. Upon completion of the reset process, the

ICS1893AF enables its MII and enables its Twisted-Pair Transmit signals.

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