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Last active Nov 23, 2020
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#include <SPI.h>
#include <MFRC522.h>
In the ESP8266, D3 pin is RST_PIN and
D4 pin is SS_PIN
#define RST_PIN D3
#define SS_PIN D4
MFRC522 reader(SS_PIN, RST_PIN);
MFRC522::MIFARE_Key key;
void setup()
Serial.begin(9600); // Initialize serial communications and wait until it is ready
while (!Serial)
// Nothing here. Just wait for serial to be present
// Just wait some seconds...
// Prepare the security key for the read and write functions.
// Normally it is 0xFFFFFFFFFFFF
// Note: 6 comes from MF_KEY_SIZE in MFRC522.h
for (byte i = 0; i < 6; i++)
key.keyByte[i] = 0xFF; //keyByte is defined in the "MIFARE_Key" 'struct' definition in the .h file of the library
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