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RTOS/AM3352: USB babble error

paddu2017
Expert 2885 points
Part Number: AM3352


Tool/software: TI-RTOS

Hi,

We need below confirmation about AM335x' USB Babble error.

1. When there is a babble error, does AM335x switch OFF the VBUS output?
2. In this case there won't be VBUS error?

Best Regards
Paddu

  • 0
    TI__Guru**** 393215 points
    The RTOS team have been notified. They will respond here.
  • 0 in reply to Biser Gatchev-XID
    TI__Guru* 95265 points
    Hi,

    I searched the USB driver code:

    case HCD_BABBLE_ERROR:
    {
    USBHCDTerm(ulIndex);
    USBHCDDeviceDisconnected(ulIndex, ulInstance);
    UsbPhyOff(ulIndex);
    USBReset(g_USBInstance[ulIndex].uiSubBaseAddr);
    g_sUSBHCD[ulIndex].EventInfo.ulEvent = USB_EVENT_BABBLE_ERROR;
    g_sUSBHCD[ulIndex].EventInfo.ulInstance = ulIndex;
    g_sUSBHCD[ulIndex].pClassDrivers[g_sUSBHCD[ulIndex].iEventDriver]->pfnIntHandler(
    &g_sUSBHCD[ulIndex].EventInfo);
    break;
    }

    Inside USBHCDTerm()

    //
    // Remove power from the USB bus.
    //
    USBHostPwrDisable(g_USBInstance[ulIndex].uiBaseAddr );

    Regards, Eric
  • 0
    TI__Guru**** 174411 points

    paddu2017 said:

    1. When there is a babble error, does AM335x switch OFF the VBUS output?

    Yes, when babble condition happens, AM335x USB controller will drive USBx_DRVVBUS pin low, which will switch OFF the VBUS output.

    paddu2017 said:
    2. In this case there won't be VBUS error?

    I don't have access to the SoC internal of the USB controller, but I never saw VBUS error happens in babble condition.