TUSB8040A: Can I write to control registers using the upstream USB port?

Brian Josel

Part Number: TUSB8040A

I am using an off-the-shelf USB hub that has the TUSB8040A part, and I only have connections to the TUSB8040A through the upstream port, which is connected to my motherboard. Is there a way to read/write to TUSB8040A control registers from the upstream port? Specifically register offset 6h bits [3:] (called batEn[3:0]). We would like to have the ability to power cycle our downstream devices by sending commands via the upstream port.

over 7 years ago

0 Malik Barton57 over 7 years ago

TI__Guru 64326 points

Hi,

If the TUSB8040A hub i configured for power switching then the USB Host can send PORT_POWER commands to TUSB8040A to control downstream port power. Keep in mind that the way USB 3.0 hubs are designed requires the USB 2.0 hub instance and the USB 3.0 hub instance to share port power control, so it is possible that turning port power off for the USB 3.0 hub port may not be enough, you may have to turn it off on the USB 2.0 hub instance as well to get it to actually turn off.

0 Brian Josel over 7 years ago in reply to Malik Barton57

Intellectual 320 points

Hello,

Can you please provide detailed instructions on how to issue PORT_POWER commands to the USB hub?

0 Malik Barton57 over 7 years ago in reply to Brian Josel

TI__Guru 64326 points

Hi,

This commands sent varies based on the OS and USB Host used. The commands to be programmed are not specific TUSB8040A but rather the SOC & OS being used, for this reason we do not provide these instructions. Please see the link below for a command posted by other user which may point you in the right direction.

https://e2e.ti.com/support/interface/f/138/t/733798

0 Malik Barton57 over 7 years ago in reply to Malik Barton57

TI__Guru 64326 points

Is there any more support needed for this issue? If so please reply with any relevant details so that I can further assist you. For now I will be marking this thread as "TI Thinks Resolved". If you have resolved your issue, please post the solution to the original problem/post for others with similar issues.

Interface

Interface forum

TUSB8040A: Can I write to control registers using the upstream USB port?