Having trouble getting USB3300 to work with STM32F407

[KK.2]

Hello there,

I've prototyped a custom PCB, but I'm having issues getting USB to work, Windows is unable to read the Device Descriptor.

The IO, from what I understand, is connected correctly and the generated code is (seemingly) successfully able to initialize the PHY, and the PC will only detect it as plugged in once the `USBD_Start` method within `MX_USB_DEVICE_Init` was executed thats generated by CubeMX.

Apart from having configured the Clocks and USB HS / Device (Com port example) it is a blank project

As the 3300 needs a 24MHz clock I've decided to configure it as shown here by using MCO2. My clock configuration looks like this: https://i.imgur.com/lAhx1jD.png

I've tried to simplify it by setting PLLI2S to x120 / 5 and thus have the MCO2 be /1 with no difference.

I've tried to switch to Full Speed over High Speed with no difference.

Any help would be appreciated, thank you.

[KK.2]

Got a 24M crystal, swapped out the 25M one, changed the clocks so the HSE is passed trough aaand... Now I cant even get it to detect on Full Speed. Back to square one I guess.

Edit: Actually that was my fault, its the same behaviour as before now.

[KK.2]

I'm slowly running out of things to try. Connected the 60MHz clkout line from the PHY to the STM with a jumper and cut the trace to prevent any possible crosstalk from that line, same result

I cut the only trace which goes across the board pretty much (ULPI data 7, because for whatever reason 0-6 are on the same side of the STM chip while 7 is on the complete opposite) and connected it with a jumper instead, same result

I painstakingly botched on a 24MHz crystal onto the PHY with its caps and resistor, same result.

Starting to wonder if all this time I've looked for a hardware bug while its just STM's implementation thats faulty. I also have a second board which confirmed that its not down to some broken component (Same problem)