LAN9500 Datasheet, PDF(30/213 Page) SMSC Corporation – USB 2.0 to 10/100 Ethernet Controller Promiscuous mode

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LAN9500 Datasheet, PDF (30/213 Pages) SMSC Corporation – USB 2.0 to 10/100 Ethernet Controller Promiscuous mode

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LAN950x

5.3.1.3 Endpoint 3 (Interrupt)

The Interrupt endpoint is responsible for indicating device status at each polling interval. The Interrupt endpoint is imple-

mented via the CTL module. When the endpoint is accessed, the Interrupt packet specified in Table 5-2 is presented to

the Host.

TABLE 5-2: INTERRUPT PACKET FORMAT

Bits

31:20

10:0

Description

RESERVED

MACRTO_INT

RX FIFO Has Frame. The RX FIFO has at least one complete Ethernet frame.

TXSTOP_INT

RXSTOP_INT

PHY_INT

TXE

TDFU

TDFO

RXDF_INT

GPIO_INT

If there is no interrupt status to report, the device responds with a NAK.

Note: The polling interval is static and set through the EEPROM. The Host can change the polling interval by

updating the contents of the EEPROM and resetting the part.

The interrupt status can be cleared by writing to Interrupt Status Register (INT_STS) on page 119.

5.3.1.4 Endpoint 0 (Control)

The Control endpoint is handled by the CTL (USB Control) module. The CTL module is responsible for handling USB

standard commands, as well as USB vendor commands. In order to support these commands, the CTL must compile

a variety of statistics and store the programmable portions of the USB descriptors. The supported USB commands can

be found in Section 5.3.2, "USB Standard Commands," on page 37.

5.3.1.5 USB Command Processing

The UDC is programmed to decode USB commands. After a standard command is decoded by the UDC, it may be

passed to the CTL for completion. The CTL is responsible for implementing the Get Descriptor and vendor commands.

In order to implement the Get Descriptor command for string descriptors, the CTL manages a 128x32 register file which

stores the string values for Language ID, Manufacturer ID, Product ID, Serial Number, Configuration, and Interface. The

RAMâs contents is initialized via the EEPROM, after a system reset occurs.

TABLE 5-3: STRING DESCRIPTOR INDEX MAPPINGS

Index

String Name

Language ID

Manufacturer ID

Product ID

Serial Number

Configuration String

Interface String

When the UDC decodes a Get Descriptor command, it will pass a pointer to the CTL. The CTL uses this pointer to deter-

mine what the command is and how to fill it.

DS00001875A-page 30

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