USB2.0 compliance testing for USB HUB devices connected to USB 2.0 HSICs in i.mx8qm

[YukioOyama]

Hello,

I would like to do USB2.0 compliance testing to a USB HUB device Microchip USB3503 connected to a USB2.0 HSIC on the i.mx8qm.

It seems to work well as a USB host when it do normal operation not compliance testing.

I don't have an oscilloscope that can analyze the USB signal, so I can't analyze everything, but at least it doesn't respond to TestJ/K/SE0_NAK in the compliance test.

On the other hand, host operation on the i.MX8QM's other USB 2.0 port responds to all compliant signals. It has a USB PHY so USB devices can be connected directly.

So I think your EHSETT for USB 2.0 compliance test with NXP Linux is working correctly.

The PID/VID that excites the compliant test can be read correctly on Linux on any ports.

Can't a USB device connected to the HUB chip excite a compliance test? I am confused if this problem is i.MX8, USB3503 or EHSETT on Linux. Please give me your advice.

Best Regards,

Yukio Oyama

[Chavira]

Hi @YukioOyama !

I am watching for the documentation of Microchip and Microchip provides their hardware design checklist.

For our side, We provide our Hardware Developer’s Guide.

Both documents are very useful to understand the problem and give you a solution.

We can provide you with more support but we need more technical information about the problem like your schematic, some measurements with an oscilloscope, kernel version, etc.

For the description of the problem, I assume that is a little configuration.

if you are using the BSP of Toradex you can consult the drivers/configuration directly with Toradex Support.

If you can't publish your schematic, or reveal more information by confidential terms you can open a new private case following the link:

https://www.nxp.com/support/support:SUPPORTHOME

[Chavira]

Hello @YukioOyama!

Thank you for contacting NXP Support!

It seems like a little error because as you mention the port works but doesn't meet the USB 2.0 compliance.

I think in this case probably should be the board, can you share a schematic, please?

Please try to check the Hardware Developer’s Guide which should meet all the specifications indicated in this guide.

You can try to move the DSE in the pin mux register of the pin to try to improve the signal integrity in the USB.

if you can't publish your schematics here please open a new private case following the link:

https://www.nxp.com/support/support:SUPPORTHOME

[YukioOyama]

Hello Chavira-san,

Let me confirm your thoughts.

When the i.MX8 HSIC receives a PID/VID that excites the test mode for compliance testing, does the HSIC issue an instruction to the hub IC device to emit a test signal for USB 2.0 compliance testing?
Or, when the hub IC device receives the PID/VID for compliance testing, does the hub IC device itself emit signals for compliance testing according to that PID/VID?

Which do you consider? If the latter, does that mean that the hub IC device stops operating the USB hub to the host (i.MX8) and enters test mode?

I am wondering if you think the hub IC device (Microchip) is the cause of this problem? Or are you asking me for schematics and peripherals to find out if it is the i.MX8 or the hub IC device because you yourself are not sure which one it is.

Best Regards,

Yukio Oyama

[Chavira]

Hi @YukioOyama!

I don't know what could be the issue.

It could be the connections or the PCB in theory the IC HUB meets the certification, but it's hard to debug the issue without an oscilloscope or another tool needed for that job.

Searching on the internet I found some oscilloscopes with the function to debug the issues and test the USB, that kinds of tools should be useful to debug the issue.

Best Regards!

Chavira

[YukioOyama]

Hello Chavira-san,

Thanks for your reply.

Our HW is built around a Toradex Apalis iMX8 4GB WB.

https://developer.toradex.com/hardware/apalis-som-family/modules/apalis-imx8/

And in Toradex Apalis iMX8 4GB WB, the schematic for the connection between the i.MX8 and the USB Hub has not been published. Only the block diagram is published. We requested the schematics several times, but they were never released.

Best Regards,

Yukio Oyama

[YukioOyama]

Hello Chavira-san,

So my question is the following.
NXP Linux has a built-in EHSET for USB 2.0 compliance testing.

https://www.usb.org/document-library/embedded-high-speed-host-electrical-test-procedure-version-101

When running NXP Linux on an i.MX8QM, the USB OTG port on the i.MX8 generates test signals with PID/VID for testing.
However, a USB port added to the HSIC with a USB hub IC will not generate a test signal.

Does the combination of your NXP Linux and i.MX8 not generate test signals for USB 2.0 compliance testing on the HSIC?

Best Regards,

Yukio Oyama

[Chavira]

Hello!

Searching internally I found an Application Note.

I hope that document could be useful to resolve all your inquiries and the current issue on your board.

https://www.nxp.com/docs/en/application-note/AN12409.pdf?_gl=1*57nzjo*_ga*MTkyNjUwOTM3OS4xNjg5ODgyMz....

Best Regards.

Chavira

[YukioOyama]

Hello Chavira-san,

Thanks for the documentation.
As written in "3.3.2 Test method and tool", I set the test mode using the HSEHET board, the USB OTG port directly connected to the CPU transitions to test mode, but the USB port by Hub IC connected to the HSIC port does not transition to test mode.

Best Regards,

Yukio Oyama