I have published all the documentation in a Github repository. If someone wants to make PCBs, I recommend that you wait a little longer until you receive my PCBs and try them.
https://github.com/giltesa/SmartHome
Ok, finally I found the Problem.
I changed the prescaler value of Timer0 becuase I needed a higher PWM Frequenciy.
Unfortuneatly this also affects the millis() function that is used in gw.wait.
It turns out taht with the changed TImer 0 Prescaler 1ms was not 1ms anymore but less. So the gw.wait(750) where only 750ms/64 which is not enough for DS18S20 conversion to take place.
this kind of optic fiber is probably only plastic so for a full DIY , you can use also fishing wire with a big power led or an old chistmass tree optic fiber lighted.....
