@xydix NRF modules are sensitive to power fluctuations, so take care that you have a stable source. Is the booster of good quality or producing noise on the power lines?. The converter can produce a high frequency signal on the powerline, also know as noise. You can try to filter the noise with a small capacitor like 100nF or maybee even smaller depending on the freqency of the noise coming from the booster. My problem was/is the distance between the GW and the sensor currently, other problems were related to power as well, solved for now (see above my findings) @rubyan Sounds like power trouble and/or distance between GW and sensor. Powering from the Nano is in genaral not a good thing. The supply might be to week. Use an external power source and some capacitors (see above) Also try to see if putting the GW and sensors at a distance helps.

@clio75 Just a warning. Just ignore it and be happy. ;)

@mfalkvidd Thx: sometimes life is so simple. I totally did not notice that this slipped in... Problem solved! And to answer my other question myself: I don't need to enable softspi in the MyConfig.h I guess. Works without it apperently.

@samuel-wieczorek Hi Samuel. I positioned the sensor over the 1 liter wheel. I did not used the TCRT5000 module, but made a custom built PCB. Howver the principle is the same (in fact the schematics is 100% the same as the TCRT module. If you go to https://www.openhardware.io/view/15/Itron-Aquadis-watermeter-sensor-V10 you can see pictures of the module. Some tips I can share with you: Shield the sensor and the rotating disk area from incoming light. This influences the sensor. Use a piece of plastic tube for example. In NL we have electrical wire tubes that can be used (the grey ones) Bring the sensor close to the disk. The reflection should do the rest. Setting up the TCRT is tricky as you have little room to manouver (considering reflection and the point where the schmit trigger swaps state) Be aware that when the disk stops with the edge near the sensor you get false readings. That is why I swapped to a software driven solution using SW hysteresis on the arduino. Hope this helps. If you can open it, I can share a DXF file with the sizes of the bottom plate I use. Let me know! Ralph