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TMS320F28377D: How to change the pin monitoring VBUS.

SY Yoon
Genius 3380 points
Part Number: TMS320F28377D
Other Parts Discussed in Thread: C2000WARE,

Hi, 

My PC can't detect the USB device in custom board.

GPIO46 (VBUS) is not connected USB port and used as other function in custom board.

So I need to change the VBUS pin and GPIO45 is connected to USB port.

I looked for the settings of VBUS, but there are only the GPIO settings in USB Libraries include examples.

Can I just change the GPIO setting for VBUS monitoring? 

GPIO_setMasterCore(45, GPIO_CORE_CPU1);
GPIO_setDirectionMode(45, GPIO_DIR_MODE_IN);

  • 0
    TI__Mastermind 41365 points

    Hi SY Yoon,

    You can configure any GPIO for Vbus monitoring, but it might be best to use one with interrupt capability. Also please note the voltage level requirements.

    Please review section '23.2.3 VBus Recommendations' in the F2837x device TRM:

    https://www.ti.com/lit/spruhm8

    Also the USB library User's Guide within the C2000WARE directory below:

    C:\ti\c2000\C2000Ware_3_03_00_00\libraries\communications\usb\f2837xd\docs

    Best,

    Kevin

  • 0 in reply to Kevin Allen18
    Genius 3380 points

    Hi,

    Could you review the USB schematic in my board?

    TMS320F28377D operates as USB devices, it can be recognized by the Host (PC).

    The 3.3V MCU power is supplied via the USB_5V0 or DC adapter power through the LDO.

    Can the USB host recognize the USB devices without VBUS and ID?

     

  • 0 in reply to SY Yoon
    TI__Mastermind 41365 points

    Hi SY Yoon,

    SY Yoon said:
    Can the USB host recognize the USB devices without VBUS and ID?

    VBUS monitoring is needed for a USB device if it is a self-powered device, i.e. not powered from the host through the USB connector. You said the MCU is powered via the USB_5V0 to LDO for 3.3V, so you wouldn't need to monitor it unless you want to or the device can be powered from elsewhere.

    ID is used for USB on-the-go. It isn't needed if you're not interested in USB OTG.

    Your USB schematic looks OK. A couple comments below:

    • D+ and D- are differential signals and should be routed as such. Ideally having 90 ohm matched impedance (USB spec)
    • May want to replace 100 ohm series resistors with lower values, I think 22 or 33 ohm are more common

    Best,

    Kevin