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STM32F7 Discovery USB FS CDC Host demo

Question asked by Turboman on Mar 24, 2016
Latest reply on Mar 30, 2016 by Turboman
Having problems getting this to work. I discovered that optimisation may have been the cause of a couple of errors.

So, if I turn off all optimisation in SW4STM32 (eclipse IDE + gcc toolchain), I can get the F7 disco board to recognise what's plugged in, return VIDs and PIDs ok, and get as far as reporting "Device not supporting CDC class" which you can debug on and find that it's failed to init that class ok. I think it's failed to init that class (using USBH_CDC_InterfaceInit) because the USBH_FindInterface is returning 0xFF instead of 0.

If I set USBH_FindInterface to always return 0, then a prolific chipset usb-serial adaptor will get as far as initialising, displaying "press button to send data" and then "sending data ..." but alas, no data on the scope. An FTDI device plugged in like this will say "CDC class started" but not ask to press the button, because the state machine in USBH_Process function is not handling a USBH_NOT_SUPPORTED status in the HOST_REQUEST state.

Anyone got any advice for getting an STM32F7 Discovery USB Host CDC project working?