Finally after some problems I was able to assemble three BL-Ctrl and the serial converter.

Why I have not built four BL-Ctrl is because I broke one Atmega microcontroller while assembling the PCBs.

Next step will be to test the BL-Ctrl modules. To do that I still need some things. First I need some possibility to connect my 12V power supply to the modules and second I need multipin connectors on the BL-Ctrl modules where I can connect the serial converter.

I will look for the parts I need at Reichelt and order them. During the assembly of the modules I realized that I miss some tools so I will order them too.

At least I did one step towards my own Mikrokopter. 😉