In this project you’re going to build a time attendance system with MFRC522 RFID Reader and Arduino. When you swipe an RFID tag next to the RFID reader, it saves the user UID and time in an SD card. It also shows if you are late or in time accordingly to a preset hour and minute.

Before getting started it’s important to layout the project main features:

It contains an RFID reader that reads RFID tags;
Our setup has a real time clock module to keep track of time;
When the RFID reader reads an RFID tag, it saves the current time and the UID of the tag in an SD card;
The Arduino communicates with the SD card using an SD card module;
You can set a check in time to compare if you are in time or late;
If you are on time, a green LED lights up, if you are late, a red LED lights up;
The system also has a buzzer that beeps when a tag is read.”

Link