Voltage of USB OTG DP pin of i.MX6

[宗標廖]

Hello,Community

I have an issue about the voltage of USB OTG DP pin of i.MX6.

In normal case, the DP pin should have a voltage change as bellow when the kernel is starting up.

※I measured it on i.MX6DLSabreAuto and connected the OTG port to PC.

But my customer met an problem. On their board, after the D+ pin rising to 0.6V, it will not fall down

and keep on 0.6V for ever.

Could you give me some advice to analyze the reason?(I think it is something about kernel,but I have not find it)

Best Regards,

ZongbiaoLiao

[igorpadykov]

Hi ZongbiaoLiao

main points for check USB_LDO (VDD_VBUS_CAP) voltage,

24MHz signal quality and possibility of ESD damage. It may be useful

to check sect.3.14 i.MX6 System Development User’s Guide (rev.1, 6/2013)

http://cache.freescale.com/files/32bit/doc/user_guide/IMX6DQ6SDLHDG.pdf

Best regards

igor

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[宗標廖]

Hi Igor

Please help me!

Thank you very much!

[igorpadykov]

Hi ZongbiaoLiao

behaviour of usb signals is described in USB 2.0 specificaion

USB.org - Documents

Best regards

igor

[宗標廖]

Hi Igor

Thank you for your reply!

In normal case,why does OTG D+ pin have a voltage change as above(why does it need this)?

Please explain the reason.

Best Regards,

ZongbiaoLiao