Arduino for STM32

Hello
In an Arduino program, I use DMA transfer to the timer. At the end of the transfer, I want to stop the timer. With STM32CubeIDE, I can do this using the "handler": HAL_TIM_PWM_PulseFinishedCallback.

But in STMduino, this callback doesn't seem to be called.

Here is my code:

extern "C" void ...

you must use PB6 instead of PB3 in the initialization! Yet the first in MX, we speak first of PB3??

on a G041F8Px I can't use the UART1 (PB7, PB3)
Even if I initialize the port with I can't send or receive.
What is strange is that the TX (PB3) is at idle low (and not high)??
Anyone have any idea, am I doing something wrong?