5222-DS02-R datasheet(26/76 Pages) BOARDCOM

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BCM5222

Preliminary Data Sheet

7/20/04

Broadcom Corporation

Page 14

10BASE-T Serial Mode

Document 5222-DS02-405-R

10BASE-T SERIAL MODE

The BCM5222 supports 10BASE-T serial mode, also known as the 7-wire interface. In this mode, 10BASE-T transmit and

receive packets appear at the MII in serial fashion, at a rate of 10 MHz. Receive packet data is output on RXD0

synchronously with RXC. Transmit packet data must be input on TXD0 synchronously with TXC. Both clocks toggle at

10 MHz.

The 10BASE-T serial mode is enabled by writing a 1 to bit 1 of the Auxiliary Multiple-PHY register (1Eh). This mode is not

available in 100BASE-TX mode. Table 4 on page 14 shows the MII pins used in this mode and their direction of operation.

SPECIAL LED MODES

FORCE LEDS ON

The SPDLED, LNKLED, ACTLED, and FDXLED outputs can be forced on (0 value) by writing a 01 to bit 5 and 4 of Shadow

DISABLE LEDS

The SPDLED, LNKLED, ACTLED, and FDXLED outputs can be forced off (1 value) by writing a 10 to bit 5 and 4 of Shadow

INTERRUPT MODE

The BCM5222 can be programmed to provide an interrupt output that is shared between the two PHYs. Three conditions

can cause an interrupt to be generated: changes in the duplex mode, changes in the speed of operation or changes in the

link status. The interrupt feature is disabled by default and is enabled by setting MII register 1Ah, bit 14. The INTR pin is

open-drain and can be wire-ORed with INTR pins of other chips on a board. The status of each interrupt source is reflected

in register 1Ah, bits 1, 2 and 3. If any type of interrupt occurs, the Interrupt Status bit, register 1Ah, bit 0, is set.

Table 4: 10BASE-T Serial Mode (7-Wire) Signals

pin LABEL

Type

DESCRIPTION

TXD0

Serial Transmit Data

TXC

Transmit Data Clock (10 MHz)

TXEN

Transmit Enable

RXD0

Serial Receive Data

RXC

Receive Data Clock (10 MHz)

CRS

Carrier Sense

COL/RXEN

Collision Detect

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