Thanks for your replies guys.
The chip most certainly says 16.000.
I managed to take a picture.
My USB output is 5V, of course. And my ~8V external power source connected to the RAW pin, should also create a 5V, if the voltage regulator does what it needs to do, according to the 16.000 reading on the chip, right?
But I get a 3,3V readout.
Both (actually 3 of them) my ProMicro's were programmed as Leonardo indeed, and I did quite some debugging over time so I programmed each chip a lot. Without any errors of unstable operations.
I will try the sketch mentioned and I'll keep you informed.
