Posted on June 20, 2018 at 22:13Hello,
We've implemented an OS-less bootloader application using the STM32_USB_Host_Library and FatFs running in a STM32F427 processor created using the CubeMX tool. The application behaves perfectly when we use USB 2.0 flash drives but it hangs when a USB 3.0 flash drive is inserted in the USB port if the board is reset using the reset pin of the CPU. When we pause the debugger in this circumstance it looks like the enumeration process cannot complete, some of the debugger screen captures are attached.
There is no issue when the board is power cycled and if the USB drive is removed and inserted again it will be recognized.
My worry is that as we use an external watchdog and if somehow the external watchdog is not cleared the board will be stuck in this state where it won't be able to detect the USB drive.
Can anyone suggest where to look for the cause of this issue, I can use a logic analyzer on the USB data lines but haven't done that yet.
Thanks a lot,
Doru
