TPS65982 PD trace view

Nic Lin

Intellectual 2020 points

Other Parts Discussed in Thread: TPS65982

Hello,

I have two questions that need your help.

(1). I get the TPS65982 EVM PD trace view shown below. What does the Left & Right stand for?

(2). I use the LECROY Mercury T2C to get this PD trace. The Mercury T2C user guide says:

The Device (UFP) should be reconnect to the Connector 1 (Left side), whereas the Host (DFP) should be connected to Connector 2 (Right side).

Is it a must? Does the connector 1&2 related to the Left&Right mentioned above?

Thanks in advance.

Best Regards

Nic

over 9 years ago

0 Rahul Sharma16 over 9 years ago

TI__Expert 6430 points

Hi Nic,

There are two Type-C connectors on the front of Lecroy Mercury-T2. The connector number one is called "Left" and the connector number two is called "Right".

In the recorded log if the packet starts with "Left" then it means that communication was initiated by the device connected to Left or connector number 1 of the Lecroy analyzer. Whereas if a packet starts with "Right" then it means that communication was initiated by the device connected to Right or connector number 2 of the Lecroy analyzer.

Hope it was clear.

Thanks,
Rahul

0 Nic Lin over 9 years ago in reply to Rahul Sharma16

TI__Intellectual 2020 points

Hi Rahul,

If Left &Right refer to the devices connected to the connector No. 1&2 respectively, then I am confused with the PD trace below. It is the TPS65982 EVM PD communication between ID2 & ID5.

Analysis:
“Left”(UFP,SNK) initiated PR_Swap; Msg ID=1;
“Right”(DFP,SRC) replied Good CRC;

“Right”(DFP,SRC) initiated Accept; Msg ID=3;
“Left”(UFP,SNK) replied Good CRC;

“Left”(DFP,SNK) initiated PS Ready; Msg ID=4;
---This packet doesn’t make sense. “Left” swapped the data role from UFP to DFP?
---I think “Left” here should be revised to “Right”. “Right” swapped the power role from SRC to SNK before sending the PS_Ready message. The Msg ID also confirms my thought. It is 4 instead of 2.
“Left”(UFP,SNK) replied Good CRC;

“Right”(UFP,SRC) initiated PS Ready; Msg ID=2;
---“Right” here should be revised to “Left”
“Left”(DFP,SNK) replied Good CRC;
---“Left” here should be revised to “Right”

In conclusion, I think Left &Right refer to SNK &SRC instead of Connector No. 1&2.
Hope I have made my confusion clear.

Thanks.
Nic

0 Rahul Sharma16 over 9 years ago in reply to Nic Lin

TI__Expert 6430 points

Hi Nic,

The name "Left" or "Right" comes from the setting you do in the Protocol Analyzer software and not by detecting Soure or Sink.

Please check the image below.

If you change the name in the setting the log will reflect accordingly.

Hope this was helpful.

Thanks,

Rahul

0 Brian Berner over 9 years ago in reply to Rahul Sharma16

TI__Mastermind 30310 points

Nic,

Usually, it is best to right-click on the Left & Right labels and click "Hide" when analyzing a complex PD Trace.

The data role, DR, (DFP/UFP) and power role, PR, (Source/Sink) in the "PD Msg" section is always accurate because it is decoded from the PD data directly.

But the "Left" and "Right" labels have given me problems during Power Role Swaps: Left & Right end up being backwards because of the Rp/Rd transition during the PR Swap, but the PD Msg data continues to be accurate.

In your PD Trace, PD Packet #183 is the first time the Left and Right labels are wrong, and they will be wrong until another PR_Swap occurs or the Type-C connection is re-established. This is consistent with Rahul's analysis in the previous reply.

0 Nic Lin over 9 years ago in reply to Brian Berner

TI__Intellectual 2020 points

Hi Brian,

Your reply is really helpful to me. Thanks a lot!

Best Regards
Nic

0 Nic Lin over 9 years ago in reply to Rahul Sharma16

TI__Intellectual 2020 points

Hi Rahul,

Thanks a lot. It is very helpful.

Best Regards
Nic

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TPS65982 PD trace view