I finally found a way to use your fingerprint sensor using this library : Adafruit_Fingerprint.h I tried this : #include <Adafruit_Fingerprint.h> #include <HardwareSerial.h> HardwareSerial mySerial(0); Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial); I solved it with this code. :D :D a...