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2-Port USB 2.0 Hub Controller
Datasheet
SMSC USB2502 19 Revision 2.3 (08-27-07)
DATASHEET
5.2 EEPROM Interface
The SMSC Hub can be configured via a 2-wire (I2C) EEPROM. (Please see Table 4.1, "7-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 Ta ble 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 (10KΩ 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 2 0424 0424 Vendor ID (assigned by USB-IF).
PID 3:2 2 2502 2502 Product ID (assigned by Manufacturer).
DID 5:4 2 0000 0000 Device ID (assigned by Manufacturer).