So i delete while(RFID.available() < 4) { } and i write >=4 in the if
Yes.
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
You need to write out what you read, to see what is going on. During the delay, scanning a tag is a waste of time.