TUSB8044A: TUSB8044A

Hello,

Please confirm that:

• A blank EEPROM is not connected to the hub.
• SMBUSz = 1
• USB_VBUS is > 450 mV
• A good thermal pad connection to ground is available.

Regards,

JMMN

Thank you. JMMN

I can confirm:

1. A blank AT24C04 is connected to the HUB, but HUB-PIN 38 (SCL/SMBCLK) and HUB-PIN 37 (SDA/SMBDAT) are connected to the AT24C04 without being pulled up or pulled down.
2. Yes. SMBUSz is high level.
3. Yes. USB_VBUS is > 450 mV, approximately 516mV.
4. Yes. A good thermal pad connection to ground is available.
5. 24MHz clock is good.
6. HUB-PIN 49(TEST) is left unconnected but measured low level. 

Ok, can you install usbview.exe or usb device tree viewer and send a screen shot of what appears when the hub is attached?

Regards,

JMMN

Thank you, JMMN.

Hello, JMMN.

1. A blank AT24C04 is connected to the HUB, but HUB-PIN 38 (SCL/SMBCLK) and HUB-PIN 37 (SDA/SMBDAT) are connected to the AT24C04 without being pulled up or pulled down.

Did this situation cause this problem?

I would not have expected the I2C to be an issue if there is no pullups on SDA/ SCL, but I noticed that the PID on the USB is set to 0002, which seems to indicate the hub read in all zeros from the EEPROM. 

Can you try removing it?

Thank you, JMMN

I removed the AT24C04, but the problem is still there. The display in the usb device tree viewer is exactly the same. So I won't send you the screenshot.

Thank you, JMMN

My schematic diagram is as follows, please check it for me.

SCHEMATIC_USB3-HUB.pdf

Hello,

I don't see the AC caps installed on the upstream SS TX pair, those need to be installed for an USB 3.0 connection to be made.

It appears that the upstream port receptacle is a Type-A receptacle instead of the expected Type-B or Type-C used for upstream facing ports.  Can you confirm the cabling is straight thru since you already have the RX - TX accounted for in the board layout?  Also, do you have access to a scope to check for traffic on the USB DP / DM lines from the upstream port to the host?

Regards,

JMMN

Thank you very much, JMMN

On the second question, "the cabling is straight thru about type-b?"，I don't have the document and schematic here. Would you like to help me and give me more instructions and specifications?

Thank you.

Hello, JMMN

I checked my board.

Although I used Type-A, pin 5 of Type-A  is connected to pin 56 of TUSB8044A. I think these connection maybe correct ?

R455 and R458 were replaced by capacitances.

Hello,

So a typical USB Type A to Type B style cable swaps RX and TX inside the cable.  It appears that typical Type A to Type A cables also do this.  See section from the USB 3.1 specification below.  This may be causing the issue since you are also swapping the RX and TX lines in your routing.

Regards,

JMMN

Thank you very much, JMMN.

1. It is true that my cables are Rx and Tx switched. I changed it.

2. TUSB8044A‘s USB2.0 HUB is working properly.

3. TUSB8044A's USB3.0 HUB does not work, and the USB device tree viewer shows that it is not a HUB.

That entry on Usb viewer is reporting as a high-speed device, it seems like the USB 3.0 handshake is not occurring.  Can you confirm the rework?  Do you have a scope available to look at the lines?

Regards,

JMMN

Thank you very much, JMMN.

The Upstream interface's Tx signal shows in the scope::

This signalling looks like LFPS polling which means that the USB 3.0 handshake is not completed.

Can you check if you see similar LFPS polling on the TX from the host?

Regards,

JMMN

Thank you, JMMN.

I don’t know What causes this problem？Is it signal integrity?

Thank you, JMMN.

I got the waveforms of TUSB8044a Tx and Rx from the scope.   Tx is first.

Since there is signalling seen on both the TX and RX sides of the connection, I believe this is a signal quality issue that is preventing the USB 3.0 link from being successfully made.  

Regards,

JMMN

Thank you, JMMN.

If there is any way to save it?  Please tell me.

I wanted to make 8044's usb3.0 work, even if it wasn't stable, and at least it can offer some improvements to the redesign.

Thanks.

Can you accept my friend request and send me a photo of your board rework over direct message?

Regards,

JMMN