USB2502-HT datasheet(19/44 Pages) SMSC

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2-Port USB 2.0 Hub Controller

Datasheet

SMSC USB2502

Revision 2.1 (12-06-06)

DATASHEET

5.2

EEPROM Interface

The SMSC Hub can be configured via a 2-wire (I2C) EEPROM. (Please see Table 4.1, "2-Port Hub

Pin Descriptions" for specific details on how to enable the I2C EEPROM option).

The Internal state-machine will, (when configured for EEPROM support) read the external EEPROM

for configuration data. The hub will then “attach” to the upstream USB host.

Please see Table 5.1 User-Defined Descriptor Data for a list of data fields available.

5.2.1

I2C EEPROM

The I2C EEPROM interface implements a subset of the I2C Master Specification (Please refer to the

Philips Semiconductor Standard I2C-Bus Specification for details on I2C bus protocols). The Hub’s I2C

EEPROM interface is designed to attach to a single “dedicated” I2C EEPROM, and it conforms to the

Standard-mode I2C Specification (100kbit/s transfer rate and 7-bit addressing) for protocol and

electrical compatibility.

Note:

Extensions to the I2C Specification are not supported.

The Hub acts as the master and generates the serial clock SCL, controls the bus access (determines

which device acts as the transmitter and which device acts as the receiver), and generates the START

and STOP conditions.

5.2.1.1

Implementation Characteristics

Please refer to the MicroChip 24AA00 DataSheet for Protocol and Programming specifics.

5.2.1.2

Pull-Up Resistor

The Circuit board designer is required to place external pull-up resistors (10K

Ω recommended) on the

SDA/SMBDATA & SCL/SMBCLK/CFG_SELO lines (per SMBus 1.0 Specification, and EEPROM

manufacturer guidelines) to Vcc in order to assure proper operation.

5.2.1.3

I2C EEPROM Slave Address

Slave address is 1010000.

Note:

10-bit addressing is NOT supported.

5.2.2

In-Circuit EEPROM Programming

The EEPROM can be programmed via ATE by pulling RESET_N low (which tri-states the Hub’s

EEPROM interface and allows an external source to program the EEPROM).

5.2.3

EEPROM DATA

Table 5.1 User-Defined Descriptor Data

FIELD

BYTE

MSB:

LSB

SIZE

(BYTES)

DEFAULT

CFG

SELF

(HEX)

DEFAULT

CFG

BUS

(HEX)

DESCRIPTION

VID

1:0

0424

Vendor ID (assigned by USB-IF).

PID

3:2

2502

Product ID (assigned by Manufacturer).

DID

5:4

0000

Device ID (assigned by Manufacturer).

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