Query on requesting APDO from Source

[BhargavGolla]

Hi ,

I am using CCG3PA as DRP , 

Setup: Connected 2 CCG3PA one as source and other sink, 

1. From sink APDO 6 is been request 16v, min 3v3 and 3Amp

2. Source is sending Alert message (Operating condition change) followed by hard reset similar to the below issue posted

https://community.infineon.com/t5/USB-EZ-PD-Type-C/Analysis-of-USB-Packet-Message-using-CY4500/m-p/3...

3. Is the alert expected from source ? if yes, Why there is alert from Source? 

4. In which scenario Operating condition change alert bit is set ? what is the expected behavior from sink for such kind of alert message from source ?

Please find sniffer capture of the scenario from below link,  

Thanks and Regards

Bhargav.

[Wang_Fred]

Hello Bhargav,

Just looks from your capture, the Alert message sent by source is caused by alert type-'Operating Condition Change'. All CCG3PA actions would follow USB-PD Spec definitions.

Please refer to the following content from PD Spec. It demonstrates trigger conditions of Operating Condition Change.

So can you please check whether either one of the conditions mentioned above is triggered on your CCG3PA source?

Thanks.

[BhargavGolla]

hi wang,

Thanks for the quick reply ,

As i mentioned above i am using  2 ccg3pa ,one as source and one as sink, 

Coming to the source part

1.alert message is initiated automatically as i have disable all power protection parameters in configuration utility. you can find the snips of configuration utility below

2.Is this alert message initiated internally or  called from ccg3pa stack..?

i want to disable this alert message automatic sequence,   i am not starting any  timer in ccg_app_task , there is no temperature sensor included in my system and otp feature is disabled in config utility.

If Alert messages are necessary then i need to understand or have full control over the alert message or warning sent as source , so which part of ccg3pa source code i need to go through..?

As of sink part

what is the expected behavior from sink for above kind of alert message from source ?

This is my ccg_app_task function as you can see i am not starting any  timer too.

Then how is the Alert message initiated..? 

wang, Can you guide me to understand the alert message initiating sequence in ccg3pa as source.

These are configuration uitlity captures 

Thanks and regards 

Bhargav

[Wang_Fred · Accepted solution]

Hello Bhargav,

The Alert message of type 'operating condition change' is initiated by PD stack which shall monitor the VBUS voltage and compare the actual value with expected value under PPS mode.

If the deviation is suddenly more than a specified threshold, stack shall consider the current mode is changed from CV to CF and send an alert. This VBUS deviation is perhaps caused by sink drawing more current.

Another issue is, in you cc trace capture, there is no GoodCRC from sink following Alert message. I believe this is perhaps the reason why Alert message repeated 3 times and then softresets sent.

1. we need to make sure what happens on VBUS. Please monitor the precise VBUS change curve at the moment 3.4V PPS contract nearly complete, and try to avoid such VBUS drop.

2. please check if CCG3PA sink device is working finely around the Alerts messages sent as no GoodCRC sent out.

Thanks, Wang

[BhargavGolla]

Hi wang , 

sorry for the late reply working on some other task, this was on hold,

Regarding the alert message issue  can you guide me to the part of the code where ccg3pa is initiating this alert messages.

As i want to have full control over this alert message initiation and condition at which ccg3pa is passing this alert messages.

1.   Vbus at APDO contract happened is 3.3V and after drawing 1 amp Vbus dipped to ~3.15v and feedback logic takes time to settle vbus back to requested voltage, But meanwhile CCg3pa stack is detecting that Vbus dip as initiating Operating conditions change and hence initiating Alert messages continuously. you can see this in below captures.

2. Sink device is working fine as i tried requesting apdo from dedicated PD sources they were providing the vbus as requested and tried drawing current upto 3 amp.

Main concern here is to have full control over Alert message initiated by source(CCG3PA) or at least to have control over the threshold limit (VBUS limit)at which this alert message is initiated as we observe this issue at 3.3v only !

 

Thanks and Regards

Bhargav.

[Wang_Fred]

Hello Bhargav,

Unfortunately the part of initiating Alert message switching between CV/CF mode is untouchable, since it's warpped within stack library.