Help with Interfacing External ULPI PHY (FUSB2805) with STM32H745 in USB HS Mode

[dplogiic]

Hi everyone,

I am working on a project where I need to interface an external ULPI PHY (FUSB2805) with the STM32H745 for high-speed USB communication using USB CDC. This is my first time working with an external USB PHY, and I am facing some difficulties.

My setup:
MCU: STM32H745
External PHY: FUSB2805 (connected via ULPI) with Type-C USB connector
IDE: STM32CubeIDE

What I have done so far:
In STM32CubeMX, I have selected the USB HS mode and configured it as CDC class.
Under USB HS settings, I have selected external PHY.
I followed the hardware design guidelines, and my schematic for connecting FUSB2805 to the STM32H745 as datasheet guidelines.
The USB connection results in a "Unknown device: Descriptor request failed" message when connecting to a PC.

Issues:
--> The USB device is not recognized by the host (shows an error message: "Unknown device: Descriptor request failed").
--> I'm unsure if there are any specific additional settings required for proper ULPI PHY communication, or if I have missed something in the STM32CubeIDE configuration.
--> Is there anything specific I should check in the hardware connection between the STM32H745 and FUSB2805?

I am attaching cubeide setup for reference. I appreciate any guidance or suggestions from those who have experience with external PHYs and the STM32H745.

Thank you in advance!

[FBL]

Hi @dplogiic 

Check which clock configuration or oscillator is configured. Ensuring an accurate clock source for USB HS operation is crucial. 

[dplogiic]

Hi @FBL 

Which is the best clock configuration I should use for an external USB HS PHY with the STM32H745IIK6?

I tried both options, but with the first option (RC48), it only works if I select 12 Mbps speed with the external PHY. However, I want to use USB HS at 480 Mbps.

I have also posted my query below.

Re: STM32H745 + FUSB2805 (ULPI PHY) – USB HS Only ... - STMicroelectronics Community

On the hardware side, I am using the FUSB2805 with a 26 MHz oscillator, and I observe a 60 MHz clock on the USB_OTG_HS_ULPI_CK pin.

However, in 480 Mbps (High-Speed) mode (again using the HS external PHY with the same clock settings), the USB does not work. The host shows a ‘device descriptor request failed’ error during enumeration.