README.md

Android Things RC522

An Android Things libray to control RFID readers based on the RC522 reader.

Based on pi-rc522 by user ondryaso

Features

• Detect MIFARE 1k tags (not tested in other tags)
• Authenticate, read and write to tags
• Change authentication keys and access bits (must be done manually)
• Increment, decrement, transfer and restore for value blocks
• Easier way of changing keys and access bits

Planned features

• Helper functions
• Better error handling

Connections

The connections vary based on the board used.

RST pin is configured programatically.

Raspberry Pi 3

RC522 Pin	RPi Pin name	RPi Pin number
SDA	GPIO8, CE0	24
SCK	GPIO11, SCKL	23
MOSI	GPIO10, MOSI	19
MISO	GPIO9, MISO	21
GND	GND	6, 9, 20, 25
RST	Any GPIO pin	--
3.3V	3V3V	1, 17

Installing

This library is available at jCenter. To install add this to your module's build.gradle

dependencies {
    compile 'com.galarzaa.android-things:rc522:1.0.0'

Usage

The use of interruptions is not supported yet.

The RC522 must be polled until a card is found, and then perform any operations you want.

Unfortunately, in Android, the UI thread shouldn't be blocked, so the polling has to be done on a separate thread e.g. AsyncTask, Runnable, etc.

To use the libary, a SpiDevice object must be passed in the constructor, along with a Gpio object for the RST pin.

Polling state

import com.galarzaa.androidthings.Rc522;
public class MainActivty extends AppCompatActivity{
    private Rc522 mRc522;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        PeripheralManagerService pioService = new PeripheralManagerService();
        try {
            /* Names based on Raspberry Pi 3 */
            SpiDevice spiDevice = pioService.openSpiDevice("SPI0.0");
            Gpio resetPin = pioService.openGpio("BCM25");
            /* Names based on NXP Pico i.MX7D I/O */
            SpiDevice spiDevice = pioService.openSpiDevice("SPI3.0");
            Gpio resetPin = pioService.openGpio("GPIO5_IO00");
            mRc522 = new Rc522(this, spiDevice, resetPin);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    private void readRFid(){
        while(true){
            boolean success = mRc522.request();
            if(!success){
                continue;
            }
            success = mRc522.antiCollisionDetect();
            if(!success){
                continue;
            }
            byte[] uid = mRc522.getUid();
            mRc522.selectTag(uid);
            break;
        }
        // Factory Key A:
        byte[] key = {(byte)0xFF, (byte)0xFF, (byte)0xFF, (byte)0xFF, (byte)0xFF, (byte)0xFF};
        // Data that will be written
        byte[] newData = {0x0F,0x0E,0x0D,0x0C,0x0B,0x0A,0x09,0x08,0x07,0x06,0x05,0x04,0x03,0x02,0x01,0x00};
        // Get the address of the desired block
        byte block = Rc522.getBlockAddress(3, 2);
        //We need to authenticate the card, each sector can have a different key
        boolean result = rc522.authenticateCard(Rc522.AUTH_A, block, key);
        if (!result) {
            //Authentication failed
            return;
        }
        result = rc522.writeBlock(block, newData);
        if(!result){
            //Could not write, key might have permission to read but not write
            return;
        }
        //Buffer to hold read data
        byte[] buffer = new byte[16];
        //Since we're still using the same block, we don't need to authenticate again
        result = rc522.readBlock(block, buffer);
        if(!result){
            //Could not read card
            return;
        }
        //Stop crypto to allow subsequent readings
        rc522.stopCrypto();
            
        
    }
}

Contributing

This library is still in development, suggestions, improvements and fixes are welcome. Please submit a pull request

Resources

• This library's javadoc
• MFRC522 product data sheet, pdf, 95 pages
• MIFARE Classic EV1 1K tags data product data sheet, pdf, 20 pages