TPS65986: Bypassing "NoResponseTimeOut" hard reset in TPS65986

Roy Hsu

Genius 9320 points

Part Number: TPS65986

Hi there,

Is there a way to bypass "NoResponseTimeOut" hard reset in TPS65986?

Since the Type-C host does not support PD, we're encountering hard reset as the log attached.

acer_didn't work.usb

Could you please advise?

Thank you.

Best regards,

Roy Hsu

over 6 years ago

0 Eric Beljaars over 6 years ago

TI__Mastermind 36751 points

Hi Roy,

From looking at your PD trace, I do not see any PD Message being sent in the first place, just the Hard Reset message. Typically the Hard Reset for NoResponseTimeOut will be sent if the device is waiting for a response to Source Capabilities. Is the TPS65986 a Source in this application?

Thank you,
Eric

0 Roy Hsu over 6 years ago in reply to Eric Beljaars

TI__Genius 9320 points

Hi Eric,

No, it's a sink. Please refer to the attached project file.

986 UFP DP - Ver_20171025.pjt

Also, here's another log file where the operation was normal.

acer_worked.usb

Do you see what might be the problem by comparing the two log files?

Thank you.

Best regards,

Roy Hsu

0 Eric Beljaars over 6 years ago in reply to Roy Hsu

TI__Mastermind 36751 points

Hi Roy,

I see a few items of concern in your .pjt file. First, I noticed that you had enable Try.SRC in the System Configuration, if your application is a Sink only, this setting could cause issues when accepting a standard Type-C implicit contract. Secondly, in your Sink Capabilities, you had the minimum current set to 900mA. If your Type-C source is USB2.0 only, it will only be able to provide 500mA. I would suggest changing the minimum to 500mA.

Thank you,
Eric

0 Roy Hsu over 6 years ago in reply to Eric Beljaars

TI__Genius 9320 points

Hi Eric,

My customer tried the project files attached but they still observed the same phonemonon.

986 UFP DP - Ver_20180116_NoTrySRC.pjt

986 UFP DP - Ver_20180116_NoTrySRC_500mA.pjt

Since the host does not support PD, there would be no PD contract going on. However, would TPS65986 still be able to support USB 2.0 under this condition?

Besides, below are the waveforms measured by my customer: (CH1: Vbus, CH2: CC1, CH3: CC2)

Could you please comment on what the problem might be?

Thank you!

Best regards,

Roy Hsu

0 Eric Beljaars over 6 years ago in reply to Roy Hsu

TI__Mastermind 36751 points

Hi Roy,

If you look at section 6.4.1.1.2 of the USB PD Spec there is a SinkWaitCapTimer timeout that will send a Hard Reset when the sink does not receive a source capabilities message from the source. This is expected behavior if you are using a Type-C only source as it will not send any PD Source Capabilities.

Thank you,
Eric

0 Roy Hsu over 6 years ago in reply to Eric Beljaars

TI__Genius 9320 points

Hi Eric,

Thanks for the information.

Another thing I'd like to know is whether TPS65986 is able to support USB 2.0 after this kind of Hard Reset?

I suppose it should be able to support USB 2.0 after the hard reset but I'm not sure if there's anything that needs to be set in the configuration.

Could you please advice?

Thank you!

Best regards,

Roy Hsu

0 Eric Beljaars over 6 years ago in reply to Roy Hsu

TI__Mastermind 36751 points

Hi Roy,

USB2.0 should not be affected in this state.

Thank you,
Eric

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TPS65986: Bypassing "NoResponseTimeOut" hard reset in TPS65986