AC101L-DS04-R datasheet(12/54 Pages) BOARDCOM

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AC101L

Preliminary Data Sheet

8/9/04

B roa dcom Co rpo rat ion

Page 2

Carrier Sense (CRS)/RXDV

Document

AC101L-DS06-R

In 100BASE-FX mode, the external fiber-optic receiver performs the signal energy detection function and communicates this

information directly to the SD signal (PIN 28).

In 10BASE-T mode, a link pulse detection circuit constantly monitors the RXP/RXN pins for the presence of valid link pulses.

CARRIER SENSE (CRS)/RXDV

Carrier sense is asserted asynchronously on the CRS pins as soon as activity is detected on the receive data stream. RXDV

is asserted as soon as a valid SSD (Start-of-Stream Delimiter) is detected. Carrier sense and RXDV are de-asserted

synchronously upon detection of a valid end of stream delimiter or two consecutive idle code groups in the receive data

stream. However, if the carrier sense is asserted and a valid SSD is not detected immediately, RXER is asserted instead of

RXDV.

In 10BASE-T mode, CRS is asserted asynchronously when the valid preamble and data activity is detected on the RXIP and

RXIN pins.

In the half-duplex mode, the CRS is activated during data transmit. In the full-duplex mode, the CRS is activated during data

receiving only.

COLLISION DETECTION

In half-duplex mode, collision detect is asserted on the COL pin whenever carrier sense is asserted and transmission is in

progress.

AUTO-NEGOTIATION

Auto-negotiation selection is on 100BASE twisted-pair PHY only; it is not operating in 100BASE fiber PHY.

In 100BASE-TX mode, auto-negotiation can be enabled or disabled by hardware or software control. When the auto-

negotiation function is enabled, the 100BASE-TX PHY automatically chooses its mode of operation by advertising its abilities

and comparing them with those received from its link partner. 100BASE-TX PHY can be configured to advertise 100BASE-

TX full-duplex or 100BASE-TX half-duplex.

The default auto-negotiation mode is configured via reset read value of ANEN/LED3 signal (pin 23) and SPD100/LED1.

Table 1: Auto-Negotiation Mode

Mode

Mode Name

Link Settings

0.13

Speed Select

The default value is SPD100.

0.12

ANEN Enable

1 = Enable Auto-negotiation.

0 = Disable Auto-negotiation.

0.8

Duplex

The default value is !ANEN && DUPLEX.

4.8/1.14

100BASE-TX Full-Duplex

The default value of this bit is SPD100 && DUPLEX.

AC101L-DS04-R 数据表(PDF) 12 Page - Broadcom Corporation.

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