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AM5728: Example connection of VBUS when using USB2.0 Host and Device

Guru 14615 points

Replies: 5

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Part Number: AM5728

Hi,

I have a question about AM572x USB2.0 .
My customer are planning to use USB2.0 2port, one port is USB Host and other is USB Device.
They have a question about how to control VBUS detection.

I understood that the companion PMIC need to sense the VBUS when using AM572x.
On the AM5728 IDK EVM, USB2.0 are Device function.
External VBUS are supplied to TPS659037 and GPIO_1 pin of TPS659037 are connected to
one of GPIO pin of AM572x to tell the VBUS detection.

In AM572x Technical Referenc Manual(spruhz6k) page.6179 and page.6180, there are each connection diagram for
USB 2.0 Host and USB2.0 Device but not both cases.
As I mention above, the customer want to use USB2.0 2 port(Host and Device) simutaneouly.
In such case, I guess PMIC need 2 input ports for VBUS and 2 VBUS detection signals are needed.
But TPS659037 have only one VBUS input pin and one VBUS detection pin.
So, how to detect 2 VBUS and who will send the two VBUS detection signal to AM572x?
Please show me the example of signal connection when using USB2.0 2port(Host and Device)?

best regards,
g.f.

  • Hello G.F.,
    I'm looking into this now. I haven't seen this particular request yet so I need to do some digging.
  • In reply to -DK-:

    Hi G.F.,
    I realized that I was overthinking this.

    The answer is that a USB Host doesn't need VBUS sense of any kind. Only USB Peripherals (devices) need VBUS sense as they use this input to attach to the bus and to also de-attach in the event that VBUS isn't present any longer.

    The BeagleBoard X-15 is a community board that uses the AM572x SoC and has both a USB Host and a USB Peripheral port.
  • Guru 14615 points

    In reply to -DK-:

    Hi DK,

    Thank you for the reply.
    I understood that USB2.0 Host doesn't need VBUS sense.
    But let me ask once more again to make me sure.
    In AM572x Technical Reference Manual(spruhz6k)page.6179
    "Figure 24-143. USB1 Controller Application: USB2.0 Host",
    it said as follow:
    **********************************************************
    Figure 24-143 shows typical application of the USB1 controller
    in USB2.0 host mode. TPS2051B power switch drives 5-V VBUS when
    required by monitoring the usb1_drvvbus output from the USB controller.
    VBUS sensing is exported to the companion PMIC. USB driver monitors
    VBUS status by listening to the PMIC interrupts and using
    the I2C1 (PMIC control) interface.
    **********************************************************
    So, VBUS sensing are not required but its optional for USB Host, is it correct.

    By the way, in figure 24-143(USB host example),
    5-V VBUS output of TPS2051B are connected to both PMIC and USB2.0 Type-A.
    So, it looks like PMIC is sensing the VBUS

    best regards,
    g.f.
  • In reply to g.f.:

    Yes,
    For Host mode operation VBUS sensing is optional.

    EDIT: Above response is for AM57xx devices. Each device in the Sitara family of devices may have different requirements.

  • Guru 14615 points

    In reply to -DK-:

    Hi DK,

    Thank you for the reply.
    I understood.

    best regards,
    g.f.

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