TNETX3150A datasheet(29/113 Pages) TI1

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TNETX3150/TNETX3150A

ThunderSWITCH™ 15-PORT 10-/100-MBIT/S ETHERNET™ SWITCH

SPWS027F – FEBRUARY 1997 – REVISED SEPTEMBER 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

uplink frame control (continued)

The FIFO is loaded with two buffers before transmission begins; this ensures a minimum transmission of 128

bytes before potential underrun can occur. Following an underrun, only one buffer is transferred with a minimum

of 64 bytes following an underrun. During transmission of a long frame (during high-traffic loads), multiple

underruns can occur.

If M00RXDVX is taken high during the data receive state of an uplink-frame reception, the data reception is

stalled until M00RXDVX is returned low. This directly connects M00TXER to M00RXDVX. This simplifies the

cascade interface, permitting the transmitting TNETX3150/TNETX3150A to apply frame control (due to

underunning) and the receiving TNETX3150/TNETX3150A to reconstruct the received frame before

transmission.

NMON interface

The NMON interface (see Figure 11) provides complete network monitoring capability at 10 Mbit/s and a partial

capability at 100 Mbit/s for the 10/100-Mbits ports. TNETX3150/TNETX3150A port selection is based on the

NMON register (0xA2). See Table 2.

The interface permits two modes of operation:

D 10-Mbit/s mode (seven-wire SNI): ports 00, 01, and 02 must be used in 10-Mbit/s SNI bit-serial mode of

operation. The signals that are provided by the interface are 10-Mbit/s bit-serial, MXXRXD, MXXRCLK,

MXXCRS, MXXCOL, MXXTXD, MXXTCLK, and MXXTXEN.

D 100-Mbit/s mode (four-bit, MII either RX or TX): if ports 00, 01, and 02 are operated in 100-Mbit/s mode (or

10-Mbit/s non-SNI), the user can select the interface to access RX or TX. If ports 03–14 are monitored in

this mode and enabled by setting the MONWIDE bit high, only the least-significant bit of the interface

contains network data (bits 1–3 are not driven). When monitoring RX data, MXXRXD3–MXXRXD0,

MXXRXDV, MXXRCLK, and MXXSPEED are provided. When monitoring TX data, MXXTXD3–MXXTXD0,

MXXTXEN, MXXTCLK, and MXXSPEED are provided.

This interface monitors the signals before any MAC processing is performed by the TNETX3150/TNETX3150A.

An RMON probe can monitor every packet on the segment connected to the port. The port selection is made

by writing to the NMON port select field.

TNETX3150A 数据表(PDF) 29 Page - Texas Instruments