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[C5535] USB VBUS interrupt

Kaka
Guru 24520 points

Hi community member,

Please let me confirm the following question.

[Question]

 When the VBUS pin inputs 5V, does the c5535 happen the interrupt?

I checked the TRM, I could not find this interrupt.

Best regards.

Kaka

  • 0
    TI__Mastermind 23785 points
    Kaka-san,
    This is documented in the TRM under "USB Controller Peripheral Mode Operation" section. For C5535 as a peripheral only device, when it detects USB_VBUS goes higher that 4.01V, it enables the data lines and set the SESSION bit. It waits for the host to send reset signal which will trigger the interrupt. In addition to the document, I have confirmed with our USB expert, David also.
    Regards.
  • 0 in reply to Steve Tsang
    Guru 24520 points

    Hi Steve,

    Thank you for your response.
    Please let me confirm your comments.

    [Question.1]
    If the USB_VBUS goes higher than 4.01V, does it set the SESSION bit automatically by device?

    [Question.2]
    To summary your comment, the interrupt for VBUS pin over 4.01V will happen by reset from Host device.

    Is my understanding correct?

    If you have any question, please let me know.
    Best regard,
    Kaka

  • 0 in reply to Steve Tsang
    Guru 24520 points
    Hi Steve,

    Thank you for your response.
    Please let me confirm your comments.

    [Question.1]
    If the USB_VBUS goes higher than 4.01V, does it set the SESSION bit automatically by device?

    [Question.2]
    To summary your comment, the interrupt for VBUS pin will happen by reset from Host device.
    Is my understanding correct?

    If you have any question, please let me know.
    Best regard,
    Kaka
  • 0 in reply to Kaka
    TI__Mastermind 23785 points
    A1: Yes. This is the protocol.A2: Yes.Regards.
  • 0 in reply to Steve Tsang
    Guru 24520 points
    Hi Steve,
    Thank you for your confirming.
    If I get more questions from my customer, please let me confirm them.

    Best regards.
    Kaka
  • 0 in reply to Kaka
    Guru 24520 points
    Hi Steve,
    Please double check your comments.
    If the VBUS pin is gereter or equal to 4.01V, the SOFTCONN bint in the POWER register is automatically set by C5535 USB phy.
    Is my understanding correct?

    I checked this operation with using C5515 EVM.
    When inputted the 5V to VBUS pin, the SOFTCONN bit does not set at this time.
    Thus, we need to set this bit by checking the VUBS bit in DEVCTL register.

    Best regards.
    Kaka
  • 0 in reply to Kaka
    TI__Mastermind 23785 points
    Kaka-san,
    No. The SOFTCONN bit is not automatically set by C5535. It assumes the firmware to set as descripted in TRM:
    "The USB2.0 controller will transition to session when it sees power (must be greater or equal to 4.01V) on
    the USB0_VBUS pin, assuming that the firmware has set the SOFTCONN bit in the POWER register and
    has enabled the data lines and there is an external host sourcing power on the USB0_VBUS line. The
    USB 2.0 controller will then set the SESSION bit upon detecting the power on the USB0_VBUS line and it
    will connect its 1.5Kohm pull-up resistor so it signifies to the external host out it is a Full-Speed device.
    Note that even when operating as a High-Speed; it has to first come up as Full-Speed. The USB2.0
    controller will then wait for a reset signal from the host."Regards.