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HS USB w/ External SMSC PHY

Question asked by Joshua on Oct 18, 2013
Latest reply on Jun 12, 2015 by Clive One
I saw several posts going back a few years regarding an issue with several different STM parts interfacing with external PHYs from SMSC (now Microchip). 

We have successfully implemented a STM32F405 with a USB3300. However, we have not had much luck with a STM32F205 with either the USB3300 or USB3340. Both seem to exhibit the same issue: there is no ChirpK generated by the device, so it ends up enumerating as FS instead of HS.

Working w/ Microchip, they have suggested as a workaround inserting a single clock delay between the ULPI register write and transmit. However, I do not appear to have access to the ULPI registers in the STM32F micros. Am I missing something here? I don't find these registers anywhere in the datasheet.

I have also read that some people had tried the USB3320 part; however there was no follow-up confirming success. Can anyone confirm success with the USB3320? What STM32F part did you implement it with? Did it require any workarounds or tricks?

We're working on a new design around the STM32F427 and would like to get this right the first time.