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USB EZ-PD Type-C

New Contributor

Dear,

I made a dock and used the CYPD4236-40LQXI_dock sample code.

Connect to a host, CC can't communicate, fail rate is about 60%.

But on other hosts, no communication has ever failed.

(1) How can I prove that this is a hosting issue?

(2) How to prove CYPD4236-40LQXI internal CC PD Pull low?

PASS Case

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Fail Case

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Best Regards,

Manu

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1 Solution
Employee

Hi Manu,

I hope, you are capturing the traces at dock end.

As you can see for passing case, dock locks as DFP (i.e., applying Rp) and Rd is applied on CC2 line.

However, on failing case, two things are possible:

- there was some bad pull-up applied on CC2 line from notebook.

- there was bad pull-down applied from notebook on CC2 line when dock switching to Rp.

However, there is no VBUS applied. I suspect dock is doing Type-C error recovery.

Regards,

Muthu

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3 Replies
Employee

Hi Manu,

I hope, you are capturing the traces at dock end.

As you can see for passing case, dock locks as DFP (i.e., applying Rp) and Rd is applied on CC2 line.

However, on failing case, two things are possible:

- there was some bad pull-up applied on CC2 line from notebook.

- there was bad pull-down applied from notebook on CC2 line when dock switching to Rp.

However, there is no VBUS applied. I suspect dock is doing Type-C error recovery.

Regards,

Muthu

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New Contributor

Hi Muthu,

How do I see bad pull-up and bad pull-down from the waveform?

Best Regards,

Manu

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Moderator
Moderator

Hi Manu,

You can check the voltage levels from the cc waveforms to see if they comply with specified levels.

For further debug, CC traces/logs are needed.

Regards,

Rajath

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