AM625: USB VBUS on and off test

Hi,

CWL said:

I'm developing a usb vbus on/off checking test.

Can you please explain the purpose of the test? Is it to simulate USB connect/disconnect?

The purpose of test is to verify is the voltage of VBUS are able to control by USB_DRVVBUS pin from USB IP. The control of USB_DRVVBUS via GPIO and USB IP is included. For now, I'm working in how to control the USB_DRVVBUS by USB IP and verify the VBUS by VBUS detection.

The USB configuration is USB Host-only connections.

Hi,

The USB_DRVVBUS pin shouldn't be in GPIO mode to control the VBUS power supply.

The xHCI controller register has a bit which can be used to control USB_DRVVBUS pin, but I haven't used it for years. I will look it up and provide the details.

Hi, Bin Liu. Yes, you are right. For GPIO control, it is just take in consideration that other GPIO(s) used to control the VBUS which is not controllable by the USB IP. You can forget about GPIO part. I'm working in USB IP part, control USB_DRVVBUS and detect VBUS by USB IP. 

I can't find a clearly instructions for these parts. 

Hi,

Thanks for the quick reply. Yes, I think these are the information I wanted. I will test it out later in EVK module.

Can guide/share me where to find this eXtensible Host Controller Interface for Universal Serial Bus [USB] Specification 3.0?

I also would like to find out how to use the VBUS detection part too. 

Hi,

The xHCI spec is available on Intel website.

VBUS is an input signal to AM62x. In USB host mode, VBUS input can be ignored in software, xHCI doesn't care about the VBUS input.

Hi, 

Before use xHCI to control the USB_DRVVBUS, other than initialise the LPSC_USB_0/LPSC_USB_1 module domain. Anything is required to be done? Is xHCI required to be initialise too? At this moment, I able to toggle PORTSC register address for USB0 and USB1. But the USB_DRVVBUS is not toggle as expected.

Hi,

Are you not doing these tests in Linux?

I have never done such PORTSC/USB_DRVVBUS test out side of Linux, and am not sure what software sequence should be done before xHCI controller can manipulate USB_DRVVBUS.