STUSB4500 issue with USB2.0 data with macOS

[RRicci]

We have an application where the STUSB4500 is used in conjunction with and STM32L4 family MCU, handling USB2.0 data.

So the STUSB provides power (USBPD) and the DP DM lines are routed to the MCU.

There is an issue specifically when using a macOS laptop (version 12.4) and connecting our device by using a USBC-to-USBC cable. The laptop correctly negotiates a power contract but does not appear as a device.

I am pretty sure this is USBPD related since if I use a USBA-to-USBC cable it works fine.

It's worth noting that this happens with both M1 and not-M1 MacBooks, while this issue does not manifest with linux and windows machine.

[NBALL]

Hello

Could you please ensure that you have set, stusb4500, bit USB_COMM_CAPABLE in NVM ?

I suspect that the macOS is checking all bits in Request message and enables its DFP only if Sink is UFP capable.

While using A-to-C cable, legacy host port always enables DFP terminations.

If you have possibility to share USBPD trace, it would be nice.

Best regards

Nathalie

[RRicci]

Dear Nathalie,

Thanks for your reply. I will check the USB_COMM_CAPABLE bit, in the meantime please see attached screenshot and csv export of pd trace.

[RRicci]

Dear Nathalie,

The USB_COMM_CAPABLE bit was not set, changing it in NVM solve the issue.

Thanks for your help

[NBALL]

Welcome 🙂

Nathalie