TUSB8044AEVM: SuperSpeed USB Connection Issues on a Specific Laptop.

Hi Sam:

    Did you use type-C to A cable? did it work when you flip the cable?

Regards

Brian

Hello Brian,

The upstream port of tusb8044aevm is type-b, so type-c to b cable was used. Flipping the cable does not change the symptoms.

Regards,

Sam

Hi Ubum:

     let me find a USBC to B cable and test with TUSB8044EVM in our lab first.

Regards

Brian

Hello Brian,

Okay. I will be waiting for the results.

For your reference, although I haven't tested on many different types of laptops, the issue occurred only on the Surface Pro 7 among the five types of laptops I have tested.

Regards,

Sam

Hi Sam:

   I tested TUSB8044A EVM with USBC to B cable and USB3  didn't work either. Main issue is the Vbus got from host was  only 1.6V , not 5V.

Can you measure Vbus on J8 ( next to USB  upstream port) on EVM ?

Regards

Brian

Hello Brian,

The VBUS voltage is 5v on J8. It seems to be a different symptom than your test results.

As shown in the attached image, the USB2 hub is recognized normally, but only the USB3 hub experiences enumeration failure.

Initially, I suspected a faulty host controller in a specific laptop, but:

1. The fact that other hubs work without issues on that laptop.
2. The symptom is reproduced in another laptop of the same model when testing with the 8044AEVM,

which leads me to investigate why the 8044AEVM is behaving differently.

On two Surface Pro 7 laptops, the rate of symptom reproduction differs. When tested 10 times each, one shows a reproduction rate of about 10-20%, while the other shows a rate of about 80-90%.

Thanks,

Sam

Hi Ubum:

    If Vbus is 5v, it should work. How is switch setting on your board?

Regards

Brian

Hello Brian,

I am using it with all switches set to off, which is the default setting.

Thanks

Above default setting should be fine Let me test with other laptop and see any difference. 

When it pass during your test, only one side can pass or both sides can pass?

Regards

Brian

Hello Brian,

When it passes, both sides can pass.

Thanks

Hi Ubum:

   Not sure  why both sides can pass  since only one side should be connected inside the cable based on below information.

    I also tested TUSB8044A EVM on other type-C port.

1st port sent out 5v but only enumerated as USB2 hub.

2nd port just sent out 1.5v without any enumeration.

   I will discuss all these test results with our system guy and see why caused different result.

Regards

brian

Hello Brian,

Is there any updated information?

Regards

Hi Ubum:

    I just got type-C analyzer and took some traffic data,, I will review the traffic data and send my feedback to you tomorrow or next monday.

Regards

Brian

This trace is C to A receptacle  connector + A plug to B plug cable + 8044A upstream, you can see  host turn on the Vbus  and  USB3 is working fine

This trace is C to B plug cable + 8044 upstream, it seems host saw the Rd from cable but did not turn on VBus, Rd is only existing 1ms and above case RD is over 100ms. Don't know why Rd on C to B cable is not stable. I may need to get another C to B cable to see any difference.

Regards

Brian

I have a question. When Rd is over 100ms and the VBus does not turn on,

Is the USB highspeed hub recognized normally?

If the VBus does not turn on, wouldn't both USB superspeed and highspeed hubs not be recognized?

Regards,

If the VBus does not turn on from DFP or host  ,  both USB superspeed and highspeed hubs will  not be recognized?

But from your case, I remember Vbus was on, is it?

Regards

Brian

Dear Brian,

Yes. In my case, the VBUS was always on when an issue occurred.

It seems that the symptoms you experienced and mine are different.

I was able to acquire another Surface Pro 7 for testing, and while the success rate was higher than the previous two laptops, the symptoms still reproduced.

The two laptops I had been testing were unable to be updated due to company policy, but this time, with the newly acquired Surface Pro 7, which could be updated, updating the system drivers and BIOS firmware seemed to resolve the issue and the symptoms did not reproduce.

If the same symptoms are found later, I will post again on this forum.

Thanks