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NFC reader with mifare tags


wbackup83
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I don't understand why using a mifare tag using the provided code i can read the tag page without authenticating ...moreover the state page ready is never accessed... for this reason the page if i change the tag still remains the same...

can you take a look at my code to understand if i m missing something or what?

Tags are found, i can print the page content without authenticating it...(commented)

 

public class ExampleScanForTags {

    private static final String HOST = "localhost";

    private static final int PORT = 4223;

 

    // Change XYZ to the UID of your NFC/RFID Bricklet

    private static final String UID = "uqB";

 

    private static short currentTagType = 0;

 

    // Note: To make the example code cleaner we do not handle exceptions. Exceptions

    //      you might normally want to catch are described in the documentation

    public static void main(String args[]) throws Exception {

        IPConnection ipcon = new IPConnection(); // Create IP connection

        // Note: Declare nr as final, so the listener can access it

        final BrickletNFCRFID nr = new BrickletNFCRFID(UID, ipcon); // Create device object

 

        ipcon.connect(HOST, PORT); // Connect to brickd

        // Don't use device before ipcon is connected

 

        // Add state changed listener

        nr.addStateChangedListener(new BrickletNFCRFID.StateChangedListener() {

            public void stateChanged(short state, boolean idle) {

            //System.out.println(state);

                try {

                    if(idle) {

                        currentTagType = 0;

                        //(short)((currentTagType + 1) % 3);

                        nr.requestTagID(currentTagType);

                     

                    }

 

                    if(state == BrickletNFCRFID.STATE_REQUEST_TAG_ID_READY) {

                        BrickletNFCRFID.TagID tagID = nr.getTagID();

                        String s = "Found tag of type " + tagID.tagType +

                                  " with ID [" + Integer.toHexString(tagID.tid[0]);

 

                        for(int i = 1; i < tagID.tidLength; i++) {

                            s += " " + Integer.toHexString(tagID.tid);

                        }

 

                        s += "]";

                        System.out.println(s);

                        //added code

                        short[] keys= {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

 

//nr.authenticateMifareClassicPage(5, (short) 0,keys);

short[] data=nr.getPage();

System.out.println(Arrays.toString(data));

                    } 

                    if(state == BrickletNFCRFID.STATE_AUTHENTICATING_MIFARE_CLASSIC_PAGE_READY) {

                    System.out.println("Ready");

                   

                    }

                    if(state == BrickletNFCRFID.STATE_AUTHENTICATING_MIFARE_CLASSIC_PAGE_ERROR) {

                    System.out.println("error");

                   

                    }

 

                } catch(Exception e) {

                    System.out.println(e);

                }

            }

        });

 

        // Start scan loop

        nr.requestTagID(BrickletNFCRFID.TAG_TYPE_MIFARE_CLASSIC);

 

        System.out.println("Press key to exit"); System.in.read();

        ipcon.disconnect();

    }

}

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I think if you call getPage you will get the page from the last successful read.

 

So if you call getPage in the REQUEST_TAG_ID_READY state, you will not actually read a new page.

 

You have to first authenticate, then request the page and then you can call getPage.

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Thanks for the reply...but it is the same: it always returns the same page with different tags and the other states are never accessed.

 

nr.addStateChangedListener(new BrickletNFCRFID.StateChangedListener() {

            public void stateChanged(short state, boolean idle) {

            //System.out.println(state);

                try {

                    if(idle) {

                        currentTagType = 0;

                        //(short)((currentTagType + 1) % 3);

                        nr.requestTagID(currentTagType);

                     

                    }

 

                    if(state == BrickletNFCRFID.STATE_REQUEST_TAG_ID_READY) {

                        BrickletNFCRFID.TagID tagID = nr.getTagID();

                        String s = "Found tag of type " + tagID.tagType +

                                  " with ID [" + Integer.toHexString(tagID.tid[0]);

 

                        for(int i = 1; i < tagID.tidLength; i++) {

                            s += " " + Integer.toHexString(tagID.tid);

                        }

 

                        s += "]";

                        System.out.println(s);

                        //added code

                        short[] keys= {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};

 

nr.authenticateMifareClassicPage(5, (short) 0,keys);

nr.requestPage(5);

short[] data=nr.getPage();

System.out.println(Arrays.toString(data));

                    } 

                    if(state == BrickletNFCRFID.STATE_AUTHENTICATING_MIFARE_CLASSIC_PAGE_READY) {

                    System.out.println("Ready");

                   

                    }

                    if(state == BrickletNFCRFID.STATE_AUTHENTICATING_MIFARE_CLASSIC_PAGE_ERROR) {

                    System.out.println("error");

                   

                    }

 

                } catch(Exception e) {

                    System.out.println(e);

                }

            }

        });

 

        // Start scan loop

        nr.requestTagID(BrickletNFCRFID.TAG_TYPE_MIFARE_CLASSIC);

 

        System.out.println("Press key to exit"); System.in.read();

        ipcon.disconnect();

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Looking at your code, you do:

 

nr.authenticateMifareClassicPage(5, (short) 0,keys);
nr.requestPage(5);
short[] data=nr.getPage();
System.out.println(Arrays.toString(data));

 

I think you should first call

 

nr.authenticateMifareClassicPage(5, (short) 0,keys);

 

then in the state STATE_AUTHENTICATING_MIFARE_CLASSIC_PAGE_READY call

nr.requestPage(5);

 

and then in the state STATE_REQUEST_PAGE_READY call

short[] data=nr.getPage();
System.out.println(Arrays.toString(data));

 

Does it work when you do that?

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Hi, it works after a few tweaks:

 

olaf@pc2:~/build20/java$ javac -cp Tinkerforge.jar:. ExampleScanForTags.java 
olaf@pc2:~/build20/java$ java -cp Tinkerforge.jar:. ExampleScanForTags
Press key to exit
Found tag of type 0 with ID [6d b8 97 f7]
Ready
page ready
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

 

The Problem with your code is that you call "nr.requestTagID(currentTagType);" every time that the Bricklet is in idle state. But it goes into idle state after it reaches any of the new states. So you call requestTagID in a loop. For me it started to work immediately after i commented out the if(idle) {...} block.

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Well, if no tag is there you will get into the state STATE_REQUEST_TAG_ID_ERROR and you have to run requestTagID from there again.

 

I attached a working program that runs in a loop.

 

Please note: All of the steps can create an error. For example: What happens if someone removes the card after the authentication but before the page was read? In this case you probably want to scan for a tag again.

 

You have to handle all of these states if you want it to be robust.

ExampleScanForTags.java

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