H1102 datasheet(25/54 Pages) MICREL

25 / 54 page

Micrel, Inc.

KSZ8041NL/RNL

September 2010

M9999-090910-1.4

Receive Data Valid (RXDV)

RXDV is driven by the PHY to indicate that the PHY is presenting recovered and decoded nibbles on RXD[3:0].

•

In 10Mbps mode, RXDV is asserted with the first nibble of the SFD (Start of Frame Delimiter), “5D”, and remains

asserted until the end of the frame.

•

In 100Mbps mode, RXDV is asserted from the first nibble of the preamble to the last nibble of the frame.

RXDV transitions synchronously with respect to RXC.

Receive Data [3:0] (RXD[3:0])

RXD[3:0] transitions synchronously with respect to RXC. For each clock period in which RXDV is asserted, RXD[3:0]

transfers a nibble of recovered data from the PHY.

Receive Error (RXER)

RXER is asserted for one or more RXC periods to indicate that a Symbol Error (e.g. a coding error that a PHY is capable

of detecting, and that may otherwise be undetectable by the MAC sub-layer) was detected somewhere in the frame

presently being transferred from the PHY.

RXER transitions synchronously with respect to RXC. While RXDV is de-asserted, RXER has no effect on the MAC.

Carrier Sense (CRS)

CRS is asserted and de-asserted as follows:

•

In 10Mbps mode, CRS assertion is based on the reception of valid preambles. CRS de-assertion is based on the

reception of an end-of-frame (EOF) marker.

•

In 100Mbps mode, CRS is asserted when a start-of-stream delimiter, or /J/K symbol pair is detected. CRS is de-

asserted when an end-of-stream delimiter, or /T/R symbol pair is detected. Additionally, the PMA layer de-asserts

CRS if IDLE symbols are received without /T/R.

Collision (COL)

COL is asserted in half-duplex mode whenever the transmitter and receiver are simultaneously active on the line. This is

used to inform the MAC that a collision has occurred during its transmission to the PHY.

COL transitions asynchronously with respect to TXC and RXC.

Reduced MII (RMII) Data Interface

The Reduced Media Independent Interface (RMII) specifies a low pin count Media Independent Interface (MII). It provides

a common interface between physical layer and MAC layer devices, and has the following key characteristics:

•

Supports 10Mbps and 100Mbps data rates.

•

Uses a 50MHz reference clock.

•

Provides independent 2-bit wide (di-bit) transmit and receive data paths.

•

Contains two distinct groups of signals: one for transmission and the other for reception.

The KSZ8041NL is configured in RMII mode after it is power-up or reset with the following:

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A 50MHz reference clock connected to REFCLK (pin 9).

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CONFIG[2:0] (pins 18, 29, 28) set to ‘001’.

The KSZ8041RNL is configured in RMII mode and outputs the 50MHz RMII reference clock to the MAC on REF_CLK (pin

19) after it is power-up or reset with the following:

•

A 25MHz crystal connected to XI (pin 9) and XO (pin 8), or a 25MHz reference clock connected to XI (pin 9).

•

CONFIG[2:0] (pins 18, 29, 28) set to ‘001’.

In RMII mode, unused MII signals, TXD[3:2] (pins 27, 26), are tied to ground.

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