TUSB4020BI: controlling on/off of downstream communication by I2C

Ryo Akashi

Genius 9470 points

Part Number: TUSB4020BI

Hello experts,

I got question about TUSB4020BI use case from customer.

They plan to use TUSB4020BI on 1 board. (No need USB connector)

Depends on situation, they need to control on/off of downstream communication.

Is it possible to do by I2C only? or SMBus is required?

Thanks and best regards,

Ryo Akashi

over 5 years ago

0 JMMN over 5 years ago

TI__Guru 60870 points

Hello Ryo,

The downstream port power and data cannot be independently controlled by the TUSB4020B hub. USB hubs are slave devices that are controlled by commands from the USB host controller. The TUSB4020B cannot be configured to report itself as a 1 port hub.

Regards,

JMMN

0 Ryo Akashi over 5 years ago in reply to JMMN

TI__Genius 9470 points

Hello JMMN,

Thank you for your reply.

I understand that slave devices that are controlled by commands from the USB host controller.

I2C signal through SDA pin is for I2X EEPROM only, not for control. Is it correct?

Also, SMBus is same as I2C use case?

Thanks and best regards,

Ryo Akashi

0 JMMN over 5 years ago in reply to Ryo Akashi

TI__Guru 60870 points

Hello Ryo,

The I2C and SMBUS are only for hub configuration: setting battery charging modes or descriptors, not active interaction or configuration of the USB system.

Regards,

JMMN

0 Ryo Akashi over 5 years ago in reply to JMMN

TI__Genius 9470 points

Hello JMMN,

Thank you for your reply. I understand I2C/SMBus is for hub configuration.

Through signal from upstream line, can we control on/off of downstream communication?

Also, do you have reference design which use TUSB4020BI?

Thanks and best regards,

Ryo Akashi

0 JMMN over 5 years ago in reply to Ryo Akashi

TI__Guru 60870 points

Hello Ryo,

Yes, downstream port power control can be set / cleared by USB commands sent from the USB host controller, but TI does not have a utility that can generate these commands. These commands are described in the USB 2.0 specification (available on usb.org) - search for PORT_POWER.

Our EVM serves as the reference design: http://www.ti.com/product/TUSB4020BI/technicaldocuments

Regards,

JMMN

0 Ryo Akashi over 5 years ago in reply to JMMN

TI__Genius 9470 points

Hello JMMN,

Thank you for your reply.

I understand. I will refer EVM.

Thanks and best regards,

Ryo Akashi

Interface

Interface forum

TUSB4020BI: controlling on/off of downstream communication by I2C