PD Packet Communication Issue with iPad Pro in Powerpack/Hub Development

Hello,

We are currently using Hub which uses CYPD3125 PD chip, It is used to connect with both Android and iOS devices. While our device works seamlessly with Android devices, we are encountering an issue when connecting to iOS devices, specifically the iPad Pro.

Issue Description:

• The Powerpack/Hub is intended to handle Power Delivery (PD) communications.
• When connected to an Android device, the PD packets are exchanged correctly, and the device functions as expected.
• However, when connected to an iPad Pro, we observe abnormal PD packet exchanges which lead to malfunctioning of the Powerpack/Hub.

Observations:

• Attached is a snapshot of the PD packets we captured while troubleshooting the issue in a scenario where the AC power adapter was initially connected. After a few seconds, we removed the plug, waited for a few seconds, and then plugged in the AC power again. This was the scenario when we captured the PD packets, as seen in the snapshot. The packets appear to be different when compared to those captured with an Android device.

• Below is the screenshot of the PD packet capture with Apple device:

• Below is the screenshot of the PD packet capture with Android device:

Technical Observations:

1. Initial Connection: The connection initiates but does not follow the expected PD communication sequence.
2. Packet Structure: In the capture, the iPad Pro shows a series of PD Msg types including Src Cap, Req, and Accept, but there are also unexpected messages such as Hard Reset and Soft Reset that disrupt the communication.
3. Timing Issues: The timestamps show irregular intervals between packets when connected to the iPad Pro, suggesting possible timing synchronization issues.
4. Unexpected Resets: The capture shows a Hard Reset event at packet 9, which is not observed in the Android device captures. This suggests the iPad Pro might be detecting an error and attempting to reset the connection.

Steps Taken:

1. Verified the firmware and hardware implementation of the Powerpack/Hub.
2. Ensured compliance with USB PD standards.
3. Tested with multiple iPad Pro units to rule out device-specific issues.

Additional Details: We have also tested with iPad Air and observed the same issue. The tests were conducted on both iOS version 16 and 17. We are attaching a USB PD capture with an Android device where it is working fine as expected. The PD packets were captured in a scenario where the AC power adapter was initially connected. After a few seconds, we removed the plug, waited for a few seconds, and then plugged in the AC power again. This was the scenario when we captured the PD packets, as seen in the snapshot.

Despite these steps, the issue persists. We seek guidance on any issues or peculiarities with iOS devices and USB PD communication.

Thanks