NFC reader with mifare tags

wbackup83 · August 7, 2018 at 11:04

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();

}

borg · August 7, 2018 at 19:53

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.

wbackup83 · August 7, 2018 at 20:14

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();

wbackup83 · August 7, 2018 at 20:17

What i would expect it would be to access the STATE_AUTHENTICATING_MIFARE_CLASSIC_PAGE_READY state after calling authenticateMifareClassicPage(). But this does not happen...

borg · August 7, 2018 at 20:26

If you comment in the "//System.out.println(state);", do you get any new state after you call authenticateMifareClassicPage()? Or no new state at all?

wbackup83 · August 8, 2018 at 05:56

If you intend as it is reported there with the print of the state commented, NO, I do not get any state at all...

borg · August 8, 2018 at 07:17

Strange, do you now what kind of mifare classic tag you have? Is it something special? Do you have a second one you could test with?

wbackup83 · August 8, 2018 at 07:26

https://www.amazon.it/gp/product/B01FLOQNMI/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

I have these... I tried with another tag of the same brand and it's the same...

borg · August 8, 2018 at 08:19

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?

wbackup83 · August 8, 2018 at 10:09

Nope...it does not enter in the state ...never..

I attach the java file so you can try it if you want

thanks again for the support

ExampleScanForTags.java

borg · August 8, 2018 at 12:02

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.

wbackup83 · August 8, 2018 at 12:51

can you please attach the code or paste it?

borg · August 8, 2018 at 13:22

See attachment.

Edit: Dont forget to change the UID back to yours.

ExampleScanForTags.java

wbackup83 · August 8, 2018 at 13:35

This works if I put the tag on the reader when i run the main... What i need is to scan and be active for other tags ... for this reason I don't understand where to put the loop ...

borg · August 8, 2018 at 13:48

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

wbackup83 · August 8, 2018 at 14:06

It works like a charm! thanks again for your kind support...I really appreciated

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NFC reader with mifare tags

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