ACR122 - Android / How to extract the UID

Question

I try to integrate an ACR122 to my android app. I'm using the ANDROID Library (http://www.acs.com.hk/en/products/3/acr122u-usb-nfc-reader/) available from ACS.

Everything work, I can detect the presence of a card but I want to extract the UID/ID of the card. Someone know the function to do that?

Do you have an example of this type of integration?

Answer 1

In case of Mifare card you need to send this APDU byte array to the card: (byte) 0xFF, (byte) 0xCA, (byte) 0x00, (byte) 0x00, (byte) 0x00 . I'm not sure about ACR122 API but probably you need to wrap this APDU into specific API method like transmit()

UPDATE

Sample code:

 byte[] command = { (byte) 0xFF, (byte) 0xCA, (byte) 0x00, (byte) 0x00, (byte) 0x00 };
 byte[] response = new byte[300];
 int responseLength;
 responseLength = reader.transmit(slotNum, command, command.length, response,response.length);
 System.out.println(new String(response));

Reader is com.acs.smartcard.Reader object and slotNum is a the slot number. I’m not sure how to find it because I don’t have ACR to test. But if you told that you was able to establish basic communication with reader probably you know slotNum.