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[AM335x] USB1 Host-mode disconnected when the cable for USB0(device-mode ) was removed.

Guru 24520 points

Hi Community member,

Please let me advice for the following phenomenon.

[Phenomenon]

 My customer have used the USBs function for their application. One of them, the USB0 is used device mode, and others is used host mode.When they removed the USB cable for USB0, the USB1(Host) disconnected.  Thus, we asked to my customer to check the USB1_VBUS.As a result, the voltage of USB1_VBUS was below 4.4V by noise.  So I think that this phenomenon is caused by noise.However when checked the interrupt of USB1IRQSTATRAW1, the value is 0x000C.  It means that Sitara was not set the USB_8 and USB_7. Thus, it seems that this phenomenon is not caused by that noise.

Just for your information, when the USB1 was powered down, the kernel showed "CAUTION: musb: Babble Interrupt Occurred".

Do you have any idea?

If you need more information in order to resolve this, please let me know.

Best regards.

Kaka

  • Hi Kato-san,

    What software (and which version) is your customer using?

  • Hi Biser,

    Thank you for your response.
    They have used the Linux 3.8 which it is provide by Beaglebone.org.
    I know that they should asked this question to Beglebone.org, but we need to answer for this as in terms of device.

    Best regards.
    Kaka
  • Sorry, kernel 3.8 is a community project and it is not supported by TI.

  • Hi Biser,
    OK. I understand.

    Please let me confirm the following question.
    [Question]
    When the USB1_VBUS is below the 4.4V, does it set the USB_7 bit and USB_6 bit on USB1IRQSTATRAW1?
    If it will set any other interrupt in this case, please let me know.

    Best regards.
    Kaka
  • I have asked the USB experts to help on this.

  • Kaka,

     

    Kato Motoki said:
    When the USB1_VBUS is below the 4.4V, does it set the USB_7 bit and USB_6 bit on USB1IRQSTATRAW1?

    For bit6 - Interrupt status for SRP detected, I am not sure, we don't support dymanic role switching including SRP, so I am not sure which condition generates SRP detected interrupt.

    For bit7 - Interrupt status for VBUS < VBUS_valid, it depends:

    - If any reason, for example in-rush current, causes VBUS drooping to below VBUS_valid, yes, bit7 interrupt generates;

    - but if other reason, for example babble condition, causes the controller to turn off session, which will turn off VBUS to 0v, then bit7 will not generate.

    It seems your case is the latter, since the reigster is 0x000C, which sets bit2 - babble condition interrupt.

    BTY, not related to this issue, but I strongly recommend your customer to move to TI SDK8.0 kernel, which has much more muture USB support than that in 3.8 kernel.

  • Hi Bin,
    Thank you for your gracious answer.
    I can understand it and will inform this to my customer.

    If I get more question from them, please let me confirm it.
    Best regards.
    Kaka