Arduino for STM32

I'd like to measure the duty-cycle of an signal with an unknown frequency, somewhere from 200 Hz up to 1 kHz. The real frequency should not matter. Another challenge is, that this signal is only send from time to time, or better to say, as long as the signal is sent, i'd like to measure and act on ...

Can programs be debugged in this setup? I used to do serial writes in Arduino, but here we have no USB-Port.

FINALLY I SUCCEEDED! :D

Downloaded the latest update from ST: https://my.st.com/content/my_st_com/en/products/development-tools/software-development-tools/stm32-software-development-tools/stm32-programmers/stsw-link007.html
and could upgrade my clone without an issue:
st-link_upgrade_successful ...

Ok, i've installed it (the drivers will automatically be installed from there also).
But now i get:

In other tutorials on the web, they have those dedicated option: Am i using the wrong boardmanager?

If i've read it right i have tree options to program the STM:

Using ST-Link programm throught the SWD interface of the chip
Using an UART-Dongle (USB to Serial adapter) with the UART way of programming
Using the USB-Port of the STM (STM32 chip needs to be prepared for this with a special ...

I've bought some bluepill boards to experiment with. After connected to USB of my PC (Win 10) the POWER-LED is on but the PC claims about an unknown device and an error while requesting device information (Code 43).

Then i read about a wrong pull-up resistor and replaced R10 with an 1,5 kOhm ...