We asked for help and got lead to a website where we found a tutorial that explained how to link the Arduino card to the tag reader.

We understood that we needed to modify the tag reader : we cut the wire that linked IRQ pin to pin 2 and re-wired it to 6. We also soldered he RST pin to pin 7.

The problem of the detection of the tag reader by the code was now solved.

We finally mixed the two codes (the one that activates the vibrating motor and the one that detects the RFID tags). We obviously had to make a few modifications in both of the codes but we managed to make them work together.

When a tag is detected, the motor vibrates !

We did it !