TUSB8044RGCT datasheet(21/61 Pages) TI1

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TUSB8044

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8.4 Device Functional Modes

8.4.1 External Configuration Interface

The TUSB8044 supports a serial interface for configuration register access. The device may be configured by an

attached I2C EEPROM or accessed as a slave by an external SMBus master. The external interface is enabled

when both the SCL/SMBCLK and SDA/SMBDAT pins are pulled up to 3.3 V at the de-assertion of reset. The

mode, I2C master or SMBus slave, is determined by the state of SMBUSz/SS_SUSPEND pin at reset. With the

integrated USB HID to I2C master, the I2C interface can also be used to program an external EEPROM or

perform updates of an external MCU's firmware.

8.4.2 I2C EEPROM Operation

The TUSB8044 supports a single-master, fast mode (400KHz) connection to a dedicated I2C EEPROM when the

I2C interface mode is enabled. In I2C mode, the TUSB8044 reads the contents of the EEPROM at bus address

1010000b using 7-bit addressing starting at address 0. The TUSB8044 will read the entire EEPROM contents

using a single burst read transaction. The burst read transaction will end when the address reaches 2DFh.

If the value of the EEPROM contents at address byte 00h equals 55h, the TUSB8044 loads the configuration

registers according to the EEPROM map. If the first byte is not 55h, the TUSB8044 exits the I2C mode and

continues execution with the default values in the configuration registers. The hub will not connect on the

upstream port until the configuration is completed.

NOTE

The bytes located above offset Ah are optional. The requirement for data in those

addresses is dependent on the options configured in the Device Configuration, and Device

Configuration 2 registers.

The minimum size I2C EEPROM required is 8Kbit.

For details on I2C operation refer to the UM10204 I2C-bus Specification and User Manual.

8.4.3 Port Configuration

The TUSB8044 port configurations can be selected by registers or efuse. The Port Used Configuration register

(USED[3:0]) define how many ports can possibly be reported by the hub. The device removable configuration

The USB 2.0 Only Port register (USB2_ONLY[3:0]) define whether or a used port is reported as part of the USB

2.0 hub or both the USB2.0 and USB3.1 hubs. The USB2_ONLY field will enable the USB2.0 port even if the

corresponding USED bit is low. The internal HID port will always be the second highest number USB2.0 port.

The billboard port will always be the highest number USB2.0 port. The table below shows examples of the

possible combinations.

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