@Yveaux Thanks for your response. I guess that's it. I have to burn a bootloader first :-). I have a USBasp Programmer for that. Can you point me to a wiring diagram that shows how to connect the programmer to the circuit board?
@kalina, Thanks. So it will not work for my configuration. Wall switch (push button) is already installed. No possibilities to draw more electrical wires.
Moreover, if i put the board near the light, i have just the Neutral and the return wire from the wall switch. No Live wire to power on the mysensors board.
I think in my ase the best way is to manage everything in my garage in the electrical main board where all the wires are mapped. I can get L + N for mysensors power supply. And i can continue to reuse the original wall switch independently of the Mysensors board.
I also have project for mini.
The project have pads for battery, battery protection IC, LIPO charger USB for charging... battery voltage measurements....
But the project is not released yet, because high temperature during charging.