IRQ D2 connection of NRF24L01+
Some sketches here on the forum use D2 as an input.
Acording to http://www.mysensors.org/build/connect_radio this port is used by the NR24L01+.
And according to https://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo, the connection of the IRQ pin is not needed by most software.
Which leads to the question: is this connection really used by mysensors?
No D2/IRQ functionality is currently not used by the MySensors library. So you can safely use the pin for something else if you want. But I'd still like to have it connected in the guides for future needs.