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USB device (gadget) pull up is missing. AM3715 OTG

Rostislav Stepanov
Prodigy 250 points
Other Parts Discussed in Thread: AM3715

Hi,

I have a problem with the USB pull up on the OTG port.

I found that three ULPI_OTG_CTRL_i registers are presented for three host ports in High-Speed USB Host Subsystem. The list of ULPI access registers is located in the Table 22-56. USBTLL Registers Mapping Summary (L4-Core Interconnect Register Space)  of AM3715 manual.

The manual doesn't mention anything about ULPI control for High-Speed USB OTG Controller.

Where may I find anything about access the ULPI control register for OTG controller?

I believe that problem appears because the OTG controller intellectual property belongs to Mentor Graphics.

 

 

  • 0
    TI__Guru 63145 points

    There are two signals connected between USB OTG controller and PHY which are used to enable the ID pin sensing circuit in the PHY and return the status of the ID pin.  The IDPULLUP output from the USB OTG controller is used to enable the ID pin sensing circuit in the PHY.  The IDDIG output from the PHY reflects the state of the ID pin of the device’s mini-AB receptacle.  Note: These signals are sent in-band across ULPI signals when the USB OTG controller is connected to an external ULPI PHY.

     

    Whether the USB OTG controller initially operates in Host mode or in Peripheral mode depends on whether it is being used in an ‘A’ device or a ‘B’ device, which in turn depends on whether the IDDIG input is low or high. When the USB OTG controller is operating as an ‘A’ device, it is initially configured to operate in Host mode. When operating as a ‘B’ device, the USB OTG controller is initially configured to operate in Peripheral mode.

     

    The device type is determined by sampling the resistance attached to the ID pin, this sampling being enabled only when required through use of the USB OTG controller IDPULLUP output to switch in an appropriate pull-up resistor on the ID pin.

     

    The USB OTG controller will automatically enable ID pin sensing (IDPULLUP = high) when a session is started. This causes the PHY to drive the IDDIG input low if an A-type connection is detected or high if a B-type connection is detected.

     

    The USB OTG controller does not require the ID pin to be pulled high when the IDDIG input is not being sampled, so you should not need to manually control the ID pin pullup.    

     

    Regards,

    Paul

  • 0 in reply to peaves
    Prodigy 250 points

    The core functionality of the OTG module is provided by a third-party IP, the Inventra MUSBMHDRC from Mentor Graphics Corporation.

    How may I obtain this module manual that is not described in the AM3715 manual?