So i delete while(RFID.available() < 4) { } and i write >=4 in the if
I've another trouble, but it happened randomly..
sometimes i have this trouble:
- scan right key -> led on -> delay -> led off
- scan wrong key -> led on -> delay -> led off
- scan wrong key -> led off
Maybe it's because i scan the right key in a wrong part of code, and the id is "saved" for the next scan?