USB 2.0 Hi-Speed Hub Controller

Datasheet

8.2.1.35Register FFh: Status/Command

BIT

 

 

NUMBER

BIT NAME

DESCRIPTION

 

 

 

7:3

Reserved

Reserved

 

 

 

2

INTF_PW_DNSMBus Interface Power Down

 

 

‘0’ = Interface is active

 

 

‘1’ = Interface power down after ACK has completed

 

 

 

1

RESETReset the SMBus Interface and internal memory back to RESET_N

 

 

assertion default settings.

 

 

‘0’ = Normal Run/Idle State

 

 

‘1’ = Force a reset of registers to their default state

 

 

 

0

USB_ATTACH

USB Attach (and write protect)

 

 

‘0’ = SMBus slave interface is active

 

 

‘1’ = The hub will signal a USB attach event to an upstream device, and the

 

 

internal memory (address range 00h-FEh) is “write-protected” to prevent

 

 

unintentional data corruption.

 

 

 

8.2.2I2C 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 SMSC hub’s I2C EEPROM interface is designed to attach to a single “dedicated” I2C EEPROM, and it conforms to the Standard-mode I2C specification (100 kbit/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.

8.2.2.1Implementation Characteristics
The hub will only access an EEPROM using the sequential read protocol.
8.2.2.2Pull-Up Resistor

The circuit board designer is required to place external pull-up resistors (10 kΩ recommended) on the SDA / SMBDATA & SCL / SMBCLK / CFG_SEL[0] lines (per SMBus 1.0 specification, and EEPROM manufacturer guidelines) to VDD33 in order to assure proper operation.

8.2.2.3I2C EEPROM Slave Address
The slave address is 1010000.Note: 10-bit addressing is NOT supported.

8.2.3In-Circuit EEPROM Programming

The EEPROM can be programmed via ATE (automatic test equipment) by pulling RESET_N low (which tri-states the hub’s EEPROM interface and allows an external source to program the EEPROM).

Revision 1.0 (3-11-09)

52

SMSC USB251x

DATASHEET