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USB EZ-PD™ Type-C Forum Discussions

arun7x8x
Level 1
Level 1
First reply posted First question asked Welcome!

Hi, 

Need to know how we can pass a custom message/command to sink controller from source side. I,e DFP to UFP after cable plugged in. We are looking for a solution(a way) to inform sink side controller to swap the Tx/Rx whenever source Flips the USB cable. We had a limitation in our design by not having a X-bar to map the channel on USB-C cable flip so now we patch up  we want to instruct sink to change the x-bar setting.

Thank you,

Arun

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3 Replies
PranavaYN
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi Arun,

Is CCG3 acting as a Source(UFP) in your design?

You can refer to Host SDK User Guide section 6.3.6.3 Sending a DISCOVER_ID VDM to understand how a VDM can be sent. But this can only be done after a successful PD contract as per the spec.

If you are designing the sink, there should be a way in sink itself to determine the flip information. It would be easier to just get that directly and change the x-bar setting accordingly. 

Please give me some background of your application so that I can help you better.

Best regards,
Pranava
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Hi,

Product is about DP to USB-C hub. We adopted 3125 USB-C host design with x-bar(version 1) solution is  working, later due to EOL of line driver by pericom we need to redesign with new line driver. We missed few note on support of high speed line swap on this line driver and ended up with the issue after board got fabricated.  Hub side cable flip we are not able to send data on correct Tx/Rx channels.

We taught of sending customized message to Sink side and request to  flip the line selection. Suggest for any solution and avoid redesign of platform.

Thank you,

Arun 

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PranavaYN
Moderator
Moderator
Moderator
500 replies posted 250 solutions authored 50 likes received

Hi Arun,

Is it possible to share the block diagram/schematic with me so that I can understand the exact issue?

If the sink has Type-C receptacle, then the flip should be handled at it's side. Even though you share the active CC (flip) information from Source/CCG3 side, it will be useless as cable plug can connect to receptacle in both orientation on the Sink side. Therefore the active CC line should be detected on the sink side and USB3 (Tx Rx) lines should be switched accordingly.

Also, if you don't have control over Sink customization, this custom message handling will not be possible. Please share block diagram/schematic so that I understand your system completely before suggesting some solution.

If you do not wish to share it here, please email it to Pranava.YN@infineon.com

Best regards,
Pranava
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