STM32F205ZET + USB3320 (USB HS Host MSC)

[Zaher]

Hello everyone,

I'm working on a new project that needs USB communication between two controllers. My initial design was based on the STM32L552, but due to market availability, I had to switch back to the STM32F205Z. So, everything has changed including the USB section.

I intend to connect the STM32F205Z (host) to another controller on the same board (peripheral). The USB3320 transceiver is used for ULPI link between the two controllers. I made some research and found a lot of contrasting info about this PHY. Some confirm it works for them on F4/F2 and some couldn't figure it out for some reason.

My implementation has to look like the following somehow:

USB signals will be shared between one connector (used to connect to ext. peripheral) and another controller on the same board in HS mode. One of them will be active at a time. The USB implementation is self-powered. Not sure yet if it's better to add FS_OTG for the external peripheral instead of sharing the USB bus signals as in the schematic above.

I thought it would be great to get some insight before proceeding to layout of the board. What do you think? Any known issues/flaws to the above design? Do you recommend another transceiver over the USB3320? Any special guidelines to follow when routing the USB HS signals between two controllers on the same PCB (besides length matching and 90 ohm impedance differentials)? And in this case where power is supplied to the external peripheral device from host, the other controller on board is self-powered, how VBUS should be connected?

Thanks

[farbodmhd]

Hi

It has passed one year from the post and probably you have figured the whole thing out, but a thing that I can tell is that the VCC3V3 (pin 20) is not a power input pin. It is the internal 3.3V regulator output and as the datasheet says, it has to be bypassed to ground with a 2.2uF low ESR capacitor. Instead, if you are powering your MCU IOs with 3.3V, it is better that the VCCIO (pin 32) be powered by 3V3.