USB2524 datasheet(36/58 Pages) MICROCHIP

36 / 58 page

USB2524

DS00001588B-page 36

 2013 - 2016 Microchip Technology Inc.

7.2

EEPROM Interface

The Microchip Hub can be configured via a 2-wire (I2C) EEPROM (256x8). (please see Table 4-2, "SMBus or EEPROM

Interface Behavior" for specific details on how to enable configuration via an I2C EEPROM).

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 port.

Please see Internal Register Set (Common to EEPROM and SMBus) for a list of data fields available.

7.2.1

I2C MASTER

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

ductor 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 trans-

fer rate and 7-bit addressing) for protocol and electrical compatibility.

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.

7.2.1.1

Implementation Characteristics

The Hub will only access an EEPROM using the Sequential Read Protocol.

7.2.1.2

Pull-Up Resistor

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

 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.

7.2.1.3

I2C EEPROM Slave Address

Slave address is 1010000.

7.2.2

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).

USB_ATTACH

USB Attach (and write protect).

0 = SMBus slave interface is active.

1 = Hub will signal a USB attach event to an upstream device, and the internal

memory (address range 00h-F0h) is “write-protected” to prevent unintentional

data corruption.}

{Note 1: This bit is write once and is only cleared by assertion of the external

RESET_N pin.}

{Note 2: If the SMBus interface is kept active after this bit is set, the

PORT_ASSIGN_12, PORT_ASSIGN_34 PORT_ASSIGN_56,

PORT_ASSIGN_7 and PORT_LOCKOUT registers may be continuously

written to reconfigure port ownership.

Note:

The Hub does not have the capability to write, or “Program”, an external EEPROM. The Hub only has the

capability to read external EEPROMs. The external eeprom will be read (even if it is blank or non-popu-

lated), and the hub will be “configured” with the values that are read.

Note:

Extensions to the I2C Specification are not supported.

Note:

10-bit addressing is NOT supported.

Bit Number

Bit Name

Description

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