TUSB8041: USB 3.0 link

How is your problem similar?  Is the host port reporting entry to compliance mode?  Or is the downstream port of the hub reporting entry to compliance mode?

Regards,

JMMN

It is not related with compliance mode.

I've implemented composite bus powered device using TUSB8041. The problem is sometimes the downstream device linked with USB 2.0. If it is soft reset, then it is linked to USB 3.0.

I've changed reset timing of HUB and downstream devices but not helpful. In addition, sometimes the link is lost. Only after unplug and plug the cable, the link can be recovered.

Is there some check point from experience?

This issue isn't resolved, but I can't clear the flag.

USB_VBUS connected to USB supply through 90.9K and 10K ohm resistors.

FULLPWRMGMTz has external pull-up to disable power management. There is no VBUS control, the downstream device is always on.

Thanks,

HJ

Hi HJ,

Can you share your schematic?  If the downstream device comes out of reset after the hub, it should always connect at USB 3.0 speeds.  If the device doesn't connect at USB 3.0 speeds, does it always drop to USB 2.0 speeds or does it sometimes not connect at all?

Regards,

JMMN

Hi, JMMN,

The downstream device connected at USB 2.0 when it fails on USB 3.0. Could you recommend how much time to delay the reset of downstream device ? and is there any software to monitor the hub device state ?

Best,

HJ

Hi HJ,

Ok, it is good that it always connects at USB 2.0 if it doesn't connect at USB 3.0 speeds, but this indicates the neither the hub or the device is going into USB 3.0 compliance mode which is the typical cause of USB 3.0 connections not occurring during power on of an embedded system.  What operating system are you running on the host?  Can you confirm that the hub is consistently connecting at USB 3.0 and USB 2.0 speeds.  Can you share the system operation steps?  For example, what order these events typically occur in:

1. Hub powered on / exits reset
2. Downstream device powered on / exits reset
3. Cable connected between hub and host

Thanks,

JMMN

Hi, JMMN,

As I've mentioned at Mon, Feb 15 2021 2:55 AM . It is a composite device integrated on the same PCB module. This problem happens when it is plugged into the host port. Mainly, I'm using this module on LINUX machine but it is observed on Windows machine also.

By the way, do you have any advice to modifying schematics ?

Thanks,

HJ

Hi Sympson,

I understand that the hub and the device are permanently connected, but are they powered on together?  Are they bus powered?  And are they powered before the host is connected?

Regards,

JMMN

Hi, JMMN,

It is bus powered module. DcDc used to supply power to all devices on the module. They are supplied altogether but have different reset timing.

It consume about 530mA when it fully operate.

Best 

Sympson

Ok, the hub+device is never powered on before the host then,  Is it just random that sometimes the device connects at USB 3.0 and sometimes USB 2.0?  Can you confirm if the hub connects at both USB 3.0 and USB 2.0 consistently?

Regards,

JMMN