Internal Pull Up on USB0_ID. How?

Alexey:

There is an IDPULLUP bit in the ULPI_OTG_CTRL_i registers.

Regards,

Michael T

Alexey,

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?

Thank you

My message was addressed to Michael.

I'll try to answer. Michael will correct me, if I am wrong here, but You will find the description of that registers by the Mentor Graphics Company after signing the NDA ;-). As I find out - this is only way to get them.

The Mentor Graphics did the USB HS Core for the TI.

In the chapter 20.1.14.30 you will find  the following:

20.1.14.30 USB Mentor Core Registers/FIFOs (Base Address + 0x400 – 0x59C)
A description of the Mentor core registers is available in the Mentor specification. The core registers are
described starting at address 0x000, but they are located in the USB 2.0 OTG module starting at 0x400.
To convert, just add 0x400 to the register address in the Mentor core specification.

Sorry, I think, I am wrong here. The FIFO registers description is from Mentors.

But the ULPI regs description is there. See Table 20-109 of the document SPRUGR0B July 2010

Alexey,

I mentioned this table as Table 22-56. USBTLL Registers Mapping Summary (L4-Core Interconnect Register Space)  of AM3715 manual.

But it is the Host related table. I need the OTG.

Look at Figure 20-1. USB Modules Overview in the manual you mentioned please. The top part is the OTG controller. The chapter 20.1 is devoted to it, but the registers you pointed to are located in the chapter 20.2.

Thank you,

Rostislav

 Alexey:

Back to your original question.  The AM3517 has an on-chip USB phy on the OTG port.

There should be NO pull-up or pull-down on the usb0_id signal.   Based on the USB cable

that is connected the usb0_id will get grounded  (in this case AM3517 is host or A device)

or will be left floating (in this case AM3517 is USB peripheral or B device).

The AM3517 on-chip USB phy has a current source and a comparator that effectively measures the

resistance from the usb0_id pin to GND.  This current source is turned on when the USB controller

performs this test.    The ULPI_OTG_CTRL_i  IDPULLUP register bit controls turning on the current source

and this action is performed by the USB controller.  Sorryfor the confusion.

Regards,

Michael T

PS: Please mark this post as answered via the Verify Answer button below if you think it answers your question.  Thanks!

Hello Michael,

About pull Up.

The company, which has developed USB OTG Stack for us, says, that this pin must have a Pull Up on it. It may be done outside of the chip. But it would be better to have one, that can be switched in a software.

Without this pull up USB OTG does not work.

That is not true.

The resistance attached to this pin is only measured when the Mentor OTG controller begins a session.  The OTG controller state machine will turn on the IDPULLUP signal to the internal PHY which enables a current source and voltage comparator while it samples the IDDIG signal sourced by a comparator in the internal PHY.  If the resistance of the ID terminal to ground is less than 10 ohms the IDDIG signal will be low which tells the OTG controller to operate in host mode.  If the resistance of the ID terminal to ground is greater than 100,000 ohms the IDDIG signal will be high which tells the OTG controller to operate in host mode.

The internal current source and comparator circuits operate from an internal core voltage supply.  Therefore the ID terminal should never be connected to an external voltage source like a pull-up resistor. 

Regards,

Paul 

Alexey,

Connecting  an external pull-up is not a good idea.You may read about pull-ups here:

http://www.beyondlogic.org/usbnutshell/usb2.shtml

USB device:

For full speed and  low speed USB pull are connected to different USB signals. For High speed USB the pull up must be disconnected after connection before high speed communication starts.

USB host:

Pull ups are inappropriate.

Only software manipulation with pull ups provides required behavior.

@Rostislav Stepanov

The question was about the USB0_ID pin only.

@peaves

It would be great, if you can tell it to our USB Serial OTG Stack distributor, because it is their requirement for the last bugfix, to have a pullup resistor on that pin.

(unfortunatelly I cann not tel you the name of the company because of NDA).

Wright now my colleague is testing that pullup, if it does, what it should.

Till now I can only say, that with the bugfix from our Stack distributor and withOUT the pullup the USB Serial does not work.

In a few moments, I can tell you, if it works with the pull up.

Alexey

The ID terminal of the AM35xx USB OTG port should never be connected to any external power source via a pull-up.  This may damage the AM37xx device.

You can ask the USB Serial OTG Stack distributor to participate in this discussion.  They may be basing their comments on experience with another device.  For example, the AM37xx requires an external ULPI PHY that may have different requirements for the ID terminal.

I do not understand how the comments from Rostislav Stepanov are related to your question.

Regards,

Paul