Hello guys I have a question. It is more related to electronics than programing but anyhow. I build myself a speedcontroller out of the wii remote, the arduino nano and the nrf24l01. Schematic and everything should be correct but I'm experiencing a strange behaviour. I desoldered the six programmer pins and now when I print the output on the serial monitor it won't output anything if I'm not touch the MISO pin with my finger. I can't figure it out why. When I touch the MISO pin with my finger it starts working and starts outputting on the serial monitor.
Posting in:
https://electronics.stackexchange.com/questions/379004/arduino-miso-pin-noise
PCB
Programm (TX)
I miss the schematics... But that sounds like you're missing a ground connection somewhere 
I added some more pictures in the other forum. I tried connecting the second ground of the arduino ot ground but noting happens. I added a 47nF cap on Vin o GND but nothing happend. The TX line is aways on 4.4V and nothing is send, but when I touch the MISO pin then voltages drops to 2.2V and it starts sending. What is more, every time I touch the Miso pin the CS pin of the nrf changes from 4.4v to 2.2v too.
I got it. I found this LINK: https://www.avrfreaks.net/forum/why-have-pullup-mosi-and-miso
So I added a 47k pullup resistor to my MISO pin and +5V and it works now. The post talks about that there is no need of such thing but now it works. Perhaps there is a pullup resistor in the arduino that isn't activ, but anyhow I will add on externaly.
Perhaps there is a pullup resistor in the arduino that isn't activ,
Yes there is, you enable it with pinMode (pin, INPUT_PULLUP)