rpi-mfrc522

A NodeJS module that provides methods to operate an MFRC522 RFID card reader connected to a Raspberry Pi through the SPI interface.

install

In your node project directory use npm to install the module...

npm install --save rpi-mfrc522

usage

In your node application require the rpi-mfrc522 module, create an instance from the module, and begin calling the rpi-mfrc522 module methods to control the MFRC522 board attached to the SPI interface.

detect card example

This example assumes the Raspberry Pi is configured with SPI device 0.0 enabled and the MFRC522 board is connected to the Raspberry SPI pins for device 0.0.

const RPiMfrc522 = require('rpi-mfrc522');
 
// create an instance of the rpi-mfrc522 class using the default settings
let mfrc522 = new RPiMfrc522();
 
// initialize the class instance then start the detect card loop
mfrc522.init()
  .then(() => {
    loop();
  })
  .catch(error => {
    console.log('ERROR:', error.message)
  });
 
 
// loop method to start detecting a card
function loop () {
  console.log('Loop start...');
  cardDetect()
    .catch(error => {
      console.log('ERROR', error.message);
    });
}
 
 
// delay then call loop again
function reLoop () {
  setTimeout(loop, 25);
}
 
 
// call the rpi-mfrc522 methods to detect a card
async function cardDetect () {
  // use the cardPresent() method to detect if one or more cards are in the PCD field
  if (!(await mfrc522.cardPresent())) {
    console.log('No card')
    return reLoop();
  }
  // use the antiCollision() method to detect if only one card is present and return the cards UID
  let uid = await mfrc522.antiCollision();
  if (!uid) {
    // there may be multiple cards in the PCD field
    console.log('Collision');
    return reLoop();
  }
  console.log('Card detected, UID ' + uidToString(uid));
  await mfrc522.resetPCD()
  reLoop();
}
 
 
// convert the array of UID bytes to a hex string
function uidToString(uid) {
  return uid.reduce((s, b) => { return s + (b < 16 ? '0' : '') + b.toString(16); }, '');
}

methods

constructor

The rpi-mfrc522 module is a Javascript class with a constructor. Create a new instance with the new operator and pass an object with any needed settings overrides.

I.E.

// load the module
const RPiMfrc522 = require('rpi-mfrc522');
 
// create an instance of the rpi-mfrc522 class
let mfrc522 = new RPiMfrc522({
  resetGPIO: 18, // override the default hardware reset GPIO of 25
  spiDevice: 1   // override the default spi device number of 0
});

resetGPIO

The restGPIO setting is the GPIO number that is used for the hardware reset on the MFRC522 board. The default GPIO is 25.

resetTime

The resetTime setting is the number of milliseconds the reset pin will be held low when the hardware reset method is called. The default is 250 milliseconds.

spiBus

The spiBus setting is the number of the SPI bus that is used. The default value is 0 for /dev/spidev0.0

spiDevice

The spiDevice setting is the number of the SPI device that is used. the default value is 0 for /dev/spidev0.0

init ()

The init method is asynchronous and should be called before using other methods from an instance of rpi-mfrc522.

I.E.

const RPiMfrc522 = require('rpi-mfrc522');
let mfrc522 = new RPiMfrc522();
 
// initialize the class instance then start the detect card loop
mfrc522.init()
  .then(() => {
    console.log('Init complete');
  })
  .catch(error => {
    console.log('ERROR:', error.message)
  });

destroy ()

Call the asynchronous destroy() method when finished with the rpi-mfrc522 instance and all resources will be released. I.E.

mfrc522.destroy()
  .then(() => {
    console.log('rpi-mfrc522 instance destroyed');
    process.exit(0);
  })
  .catch(error => {
    console.log('rpi-mfrc522 instance destroy failed');
    process.exit(1);
  });

cardPresent ()

The asynchronous cardPresent() method is used to check if one or more cards are present in the electrical field of the MFRC522. I.E.

mfrc522.cardPresent()
  .then(present => {
    if (present) {
      console.log('Card present');
    }
    else {
      console.log('No card present');
    }
  })
  .catch(error => {
    console.log('Error checking for present card.', error.message);
  });

antiCollision ()

After a card is detected in the field use the antiCollision() asynchronous method to verify if only one card is detected and return the UID array for the card. I.E.

mfrc522.antiCollision()
  .then(uid => {
    if (uid) {
      console.log('Anti-collision success, UID array:', uid);
    }
    else {
      console.log('Collision, multiple cards in the field?');
    }
  })
  .catch(error => {
    console.log('Error checking anti-collision.', error.message);
  });

selectCard (uid)

Prepare to communicate with a detected card by selecting the card with the asynchronous selectCard() method. I.E.

mfrc522.selectCard(uid)
  .then(select => {
    if (select) {
      console.log('Card successfully selected.');
    }
    else {
      console.log('Failed to select card.');
    }
  })
  .catch(error => {
    console.log('Error selecting card.', error.message);
  });

auth1A (sector, key, uid)

Attempt authentication with a selected card using the specified memory sector on the card, with the provided key array and card uid array. I.E.

let key = [0xFF,0xFF,0xFF,0xFF,0xFF,0xFF]; // default manufacturer key
mfrc522.auth1A(8, key, uid)
  .then(auth => {
    if (auth) {
      console.log('Authentication successful.');
    }
    else {
      console.log('Authentication failed.');
    }
  })
  .catch(error => {
    console.log('Error authenticating.', error.message);
  });

stopCrypto1()

Stop cryptographic communication between the MFRC522 board and the RFID card. I.E.

mfrc522.stopCrypto1()
  .then(() => {
    console.log('Crypto communication stopped.');
  })
  .catch(error => {
    console.log('Error stopping crypto.', error.message);
  });

readSector (sector)

After authentication it is possible to read the 16 byte sector on the card. I.E.

mfrc522.readSector(8)
  .then(data => {
    console.log('Sector 8:', data);
  })
  .catch(error => {
    console.log('Error reading sector.', error.message);
  });

writeSector (sector, data)

Write 16 bytes to a sector.

mfrc522.writeSector(8, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15])
  .then(write => {
    if (writeSPI) {
      console.log('Write successful.');
    }
    else {
      console.log('Write failed.');
    }
  })
  .catch(error => {
    console.log('Error writing sector.', error.message);
  });

idlePCD ()

Place the MFRC522 in an idle state.

mfrc522.idlePCD()
  .catch(error => {
    console.log('Error idling PCD.', error.message);
  });

resetPCD ()

Software reset the MFRC522.

mfrc522.resetPCD()
  .catch(error => {
    console.log('Error resetting PCD.', error.message);
  });

hardwareReset ()

Perform a hardware reset on the MFRC522

mfrc522.hardwareReset()
  .catch(error => {
    console.log('Error hardware resetting PCD.', error.message);
  });

TODO

• implement key write