STM32F103C8T6 does not get into DFU Bootloader Mode - no DTR Reset

[mani9876]

Hello!

I have some new Blue Pill Boards with STM32F103C8T6 and I ran into the following issue:

I've uploaded the generic_boot20_pc13.bin (also tried the fastboot version) using an USB-UART Adapter.

This works well, I can program the STM32 via Arduino IDE.

Afterwards, the Blink Example runs, I have a new Serial Port (CDC) which also runs perfectly.

However the Magic Reset via DTR doesn't seem to work, if I try to program the STM32 again, I am never able to get the board into DFU Bootloader Mode again.

Has anyone an idea, why this isn't working? I've tried the same procedure, with an old Bluepill (about 4 years old). And everything works as expected.

Thanks!

EDIT:
I've justed swapped the two STM32F103C8T6 between the two boards - it seems to be an issue directly with the STM32 - do you know if there are any difference although both have written "STM32F103C8T6" on them? Maybe a chinese clone?