Hi there,
We are designing in the STM32H753 and would like to use the factory DFU bootloader. We are able to use the bootloader on the H743 nucleo board, but on our PCB it fails to complete any actions giving a "connection to the target" lost error in STM32Cube Programmer.
At first we thought there was an issue with the USB hardware/routing, however our application is able to use the USB as a virtual COM port with no issues when using an external crystal (HSE) for both the main system clock and USB clock. However, when using the internal oscillator we get some issues - the device always enumerates, but sometimes fails with device code error 10: failed to restart device. Again though, using an external crystal we have no issues.
I have seen in the errata sheet that the CRS system using USB SOF does not work, and I am wondering whether this could cause the issues. It would explain why using the internal oscillator gives us problems in our applications. What does the factory bootloader use as the CRS source - is it USB SOF, or an external crystal? We note that the dev kit has both an LSE and HSE fitted. We can modify our design to add these if they will correct the issue, but need some guidance. Any other pointers to investigate the issue would also be appreciated.
Thanks,
Travis
