STM32duino bootloader has been updated to resolve some problems with the fastboot bootloader

[rogerclark]

I noticed that I was not able to upload to the 'fastboot' version of the bootloader, immediately after installing the bootloader, but after I was able to upload the first sketch, by pulling Boot1 high to hold the bootloader in DFU mode, the problem was fixed and I could subsequently upload without a problem.

I think the problem was that the "Congratulations" sketch that is merged with the bootloader, to display the welcome message, had not been updated since 2017, and hence that binary application probably didn't include the code that set flags in the non-volatile storage register which the bootloader uses to hold in DFU mode, which is essential for the fastboot version, as it does not hold in DFU mode otherwise.

I've now recompiled the Congratulations sketch and saved the binary for the generic F103C and also for the Maple mini
I've not updated the GD32 version, as the GD32 variant was removed as an option some time ago due to differences in its functionality from the STM32 and lack of availability of these boards.

[Juraj]

yes. it caused some confusion. thank you