ISOUSB211DPEVM: USB flash drive is not recognized when the PC restarts.

Hi Watanabe-san,

Welcome to TI E2E forum!

Thanks for letting us know about the issue you are facing.
Since you are using the EVM, I am assuming that the upstream side is powered by the USB port from PC and the downstream side is powered by the isolated power supply generated by the onboard device SN6507.

Please allow me to test this setup by restarting the PC and come back to you by Wednesday next week. Thanks.

Regards,
Koteshwar Rao

Hi Koteshwar Rao,

How were the test results below ?
We are incorporating ISOUSB211 into our product during production, but this issue is also occurring on the customer's side.
Could you please advise us on possible countermeasures?

Thank you and best regards,

Hi Watanabe-san,

We have tested the EVM by connecting it to a laptop. We do see that the USB flash drive is not detected when the laptop is refreshed but if the laptop is shutdown and then started again, we see the flash drive being recognized correctly. Not sure if you will be able to follow shutdown and start method, but this seems to avoid the issue.

We are currently investigating this issue. It might take some time for us to understand more and find out a solution. Apologies for the inconvenience.

Regards,
Koteshwar Rao

Hi Koteshwar Rao,

Thank you for your reply.

I recorded the behavior when the PC was restarted with a USB flash drive and a USB camera connected.
Neither device is recognized correctly after the restart, but they are recognized when re-plugged.

Thank you and best regards,

Hi Watanabe-san,

Thank you for sharing the video, this is very helpful. I understand the issue clearly now, we are looking into this. I will be able to come back to you at a later time with suitable suggestions, thanks.

Regards,
Koteshwar Rao

Hi Koteshwar Rao,

How has it been since then? We look forward to your suggestions on countermeasures.

Thank you and best regards,

Hi Watanabe-san,

Accidentally marked this resolved, I have set the status to open thread again. Please let me know if any issue occurred with this E2E thread.

Regards,
Aaditya Vittal

Hi Aaditya Vittal,

How has it been since then? We look forward to your suggestions on countermeasures.

Thank you and best regards,

Hi Watanabe-san,

Thank you for your patience.
The device doesn't have any options to externally configure or restart, therefore, this issue can't be addressed using any external components. We are still looking into this to understand how best this can be addressed. At the moment, we haven't arrived at any solution.

If it is an option for you to implement a solution to power cycle the device by turning OFF/ON the power supply to ISOUSB211 after PC is restarted through software control, then this issue can be addressed at system-level. Let us know if this is something you will be able to implement in your system. Thanks.

Regards,
Koteshwar Rao

Hi Watanabe-san,

Hope you are doing good.

While we are investigating this issue, we now are unable to recreate the issue you have reported. We are not quite sure the reason for disappearance of the issue but we did have our PC OS updated with security update from Windows. I am sharing below the latest configuration of the PC we have used for testing and unable to recreate the issue.

Edition    Windows 11
Version    23H2
OS build    22631.4602
Experience    Windows Feature Experience Pack 1000.22700.1055.0

If possible, could you please share your PC OS build information in the above format?
If your build is older than the one I have listed and if you see an option to update your OS, could you please update and try again?

Regards,
Koteshwar Rao

Hi Koteshwar Rao,

Thank you for your reply.

The OS build information of my PC is as follows. I have also attached an image.

Edition Windows 11 Pro
Version 23H2
OS build 22631.4751
Experience Windows Windows Feature Experience Pack 1000.22700.1055.0

Thank you and best regards,

I will inform you of the additional information.

I shared the video three months ago, but the USB memory is still not recognized under the following conditions.

• When the PC is powered on
• When the PC is restarted
• When the PC wakes up from sleep

I have found that when a USB hub is inserted between the PC and the EVM, the recognition issue does not occur, and the USB memory is recognized normally. I have attached a photo. This may be because the power-on reset function of the hub IC inside the USB hub is working.

I hope this information helps resolve the issue.

Hi Watanabe-san,

I appreciate your response and for sharing additional test information with the USB hub. This is useful and will help us resolve the issue better. Thanks again.

Regards,
Koteshwar Rao

Hi Watanabe-san,

We are still unable to create the issue on our EVM, we have tried with multiple EVMs and multiple PCs.
Can you please share a close-up photograph of ISOUSB211 chip so that I can read the top marking?

I am showing below an example chip where the top marking is clearing visible. Thanks.

Regards,
Koteshwar Rao

Hi Koteshwar Rao,

Thank you for your reply.

I will send you an image of my EVM.

Thank you and best regards,

Hi Watanabe-san,

Thank you for your quick response, appreciate it.

It looks like the EVM has pre-production X-marked sample (XISOUSB211). It would be helpful to test the current samples. To order current samples for free, could you please place a request at the link below by clicking "Request sample" under the column "Samples"?

https://www.ti.com/product/ISOUSB211#order-quality

Once you receive the samples, please replace the EVM with new samples, test again and let us know the results. Thanks.

Regards,
Koteshwar Rao

Hi Koteshwar Rao,

Thank you for your reply.

I replaced it with a new isolator IC without the X-mark and confirmed that the issue was resolved.

Does this issue occur with the X-marked sample (XISOUSB211)?

Thank you and best regards,