Code is compatible to Arduino and ESP8266 (NodeMCU)
Set the Pin for the RST and i2c address!
#define RST_PIN 6 // Arduino UNO
// #define RST_PIN 14 // D5 on NodeMCU
// 0x28 is i2c address of the NFC Reader. Check your address with i2cscanner if not match.
MFRC522mfrc522(0x28,RST_PIN);// Create MFRC522 instance.