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Nowadays it is extensively used in offices where employees have issued an RFID card and their attendance is marked when they touch their card to the RFID reader. It’s a new technology and is expanding day by day. It is an RFID module and is used for scanning RFID cards. MFRC522 RFID Reader is a very simple yet effective module. In this project, we have designed RFID RC522 Based Attendance System Using Arduino with Data Logger. RFID RC522 Attendance System Using Arduino with Data Logger

You can only write within a file at once, so you need to close a file before proceeding to the next one. To read the data saved on your file: dataFile.read() You can also use the print() or println() functions to print data into the file: dataFile.print(data) ĭataFile.println(data) // followed by a new line In which the dataFile is the file object created previously and the data is what you want to write in the file. To write data to the currently open file, you use: dataFile.write(data) If the data.txt file already exists, Arduino will open the file instead of creating another one. This line of code creates a file called data.txt on your SD card. The first parameter of this function is the name of the file, data.txt, and the FILE_WRITE argument enables you to read and write into the file. For example: dataFile = SD.open("data.txt", FILE_WRITE)

To open a new file in the SD card, you need to create a file object that refers to your data file. You also have to initialize the SD card module at the Chip Select (CS) pin – in our case, pin 4. To write and read from the SD card, first you need to include the SPI and SD libraries: #include The SD library provides useful functions for easily write in and read from the SD card.