Thank you so much for your help! After uploading the test file the "sound sensor reading" says 0, no response for sounds, however both led diods on the sound sensor desk are lit. I have tried another sound sensor with the same result. The connection of the sound sensor have been made according to the wiring scheme (pin A6). The touch sensor connection was wrong and after correction it works fine now.

Tomáš Vlasák try to adjust the resistivity by rotating the small potentiometer on the sensor with the screwdriver, it could be that is all dialled down. You can also connect to other pin like A3 for example and also change in the code to see if there is any difference.

So the touch sensor is fine?

Thank you again!! The potentiometer was not the problem. There has to be something wrong with the pin A6 on my I/O shield. The A3 pin works perfect and the sensor problem is solved now. Finally I managed to assemble my first Otto! Both my girls are excited and tomorrow I'm going to build the second one (for my younger daughter). After that I'm thinking about Otto Wheels and then maybe Ninja, who knows. :-) I any case Otto DIY is a great project. Thank you for creating it!

Tomáš Vlasák you are welcome keep us updated here in the community of your progress