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Android APIs
public final class

MifareUltralight

extends Object
implements TagTechnology
java.lang.Object
   ↳ android.nfc.tech.MifareUltralight

Class Overview

Provides access to MIFARE Ultralight properties and I/O operations on a Tag .

Acquire a MifareUltralight object using get(Tag) .

MIFARE Ultralight compatible tags have 4 byte pages PAGE_SIZE . The primary operations on an Ultralight tag are readPages(int) and writePage(int, byte[]) .

The original MIFARE Ultralight consists of a 64 byte EEPROM. The first 4 pages are for the OTP area, manufacturer data, and locking bits. They are readable and some bits are writable. The final 12 pages are the user read/write area. For more information see the NXP data sheet MF0ICU1.

The MIFARE Ultralight C consists of a 192 byte EEPROM. The first 4 pages are for OTP, manufacturer data, and locking bits. The next 36 pages are the user read/write area. The next 4 pages are additional locking bits, counters and authentication configuration and are readable. The final 4 pages are for the authentication key and are not readable. For more information see the NXP data sheet MF0ICU2.

Implementation of this class on a Android NFC device is optional. If it is not implemented, then MifareUltralight will never be enumerated in getTechList() . If it is enumerated, then all MifareUltralight I/O operations will be supported. In either case, NfcA will also be enumerated on the tag, because all MIFARE Ultralight tags are also NfcA tags.

Note: Methods that perform I/O operations require the NFC permission.

Summary

Constants
int PAGE_SIZE Size of a MIFARE Ultralight page in bytes
int TYPE_ULTRALIGHT A MIFARE Ultralight tag
int TYPE_ULTRALIGHT_C A MIFARE Ultralight C tag
int TYPE_UNKNOWN A MIFARE Ultralight compatible tag of unknown type
Public Methods
void close ()
Disable I/O operations to the tag from this TagTechnology object, and release resources.
void connect ()
Enable I/O operations to the tag from this TagTechnology object.
static MifareUltralight get ( Tag tag)
Get an instance of MifareUltralight for the given tag.
int getMaxTransceiveLength ()
Return the maximum number of bytes that can be sent with transceive(byte[]) .
Tag getTag ()
Get the Tag object backing this TagTechnology object.
int getTimeout ()
Get the current transceive(byte[]) timeout in milliseconds.
int getType ()
Return the MIFARE Ultralight type of the tag.
boolean isConnected ()
Helper to indicate if I/O operations should be possible.
byte[] readPages (int pageOffset)
Read 4 pages (16 bytes).
void setTimeout (int timeout)
Set the transceive(byte[]) timeout in milliseconds.
byte[] transceive (byte[] data)
Send raw NfcA data to a tag and receive the response.
void writePage (int pageOffset, byte[] data)
Write 1 page (4 bytes).
[Expand]
Inherited Methods
From class java.lang.Object
From interface android.nfc.tech.TagTechnology
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Constants

public static final int PAGE_SIZE

Added in API level 10

Size of a MIFARE Ultralight page in bytes

Constant Value: 4 (0x00000004)

public static final int TYPE_ULTRALIGHT

Added in API level 10

A MIFARE Ultralight tag

Constant Value: 1 (0x00000001)

public static final int TYPE_ULTRALIGHT_C

Added in API level 10

A MIFARE Ultralight C tag

Constant Value: 2 (0x00000002)

public static final int TYPE_UNKNOWN

Added in API level 10

A MIFARE Ultralight compatible tag of unknown type

Constant Value: -1 (0xffffffff)

Public Methods

public void close ()

Disable I/O operations to the tag from this TagTechnology object, and release resources.

Also causes all blocked I/O operations on other thread to be canceled and return with IOException .

Requires the NFC permission.

Throws
IOException

public void connect ()

Enable I/O operations to the tag from this TagTechnology object.

May cause RF activity and may block. Must not be called from the main application thread. A blocked call will be canceled with IOException by calling close() from another thread.

Only one TagTechnology object can be connected to a Tag at a time.

Applications must call close() when I/O operations are complete.

Requires the NFC permission.

Throws
IOException

public static MifareUltralight get ( Tag tag)

Get an instance of MifareUltralight for the given tag.

Returns null if MifareUltralight was not enumerated in getTechList() - this indicates the tag is not MIFARE Ultralight compatible, or that this Android device does not implement MIFARE Ultralight.

Does not cause any RF activity and does not block.

Parameters
tag an MIFARE Ultralight compatible tag
Returns
  • MIFARE Ultralight object

public int getMaxTransceiveLength ()

Return the maximum number of bytes that can be sent with transceive(byte[]) .

Returns

public Tag getTag ()

Get the Tag object backing this TagTechnology object.

Returns

public int getTimeout ()

Get the current transceive(byte[]) timeout in milliseconds.

Requires the NFC permission.

Returns
  • timeout value in milliseconds

public int getType ()

Return the MIFARE Ultralight type of the tag.

One of TYPE_ULTRALIGHT or TYPE_ULTRALIGHT_C or TYPE_UNKNOWN .

Depending on how the tag has been formatted, it can be impossible to accurately classify between original MIFARE Ultralight and Ultralight C. So treat this method as a hint.

Does not cause any RF activity and does not block.

Returns
  • the type

public boolean isConnected ()

Helper to indicate if I/O operations should be possible.

Returns true if connect() has completed, and close() has not been called, and the Tag is not known to be out of range.

Does not cause RF activity, and does not block.

Returns
  • true if I/O operations should be possible

public byte[] readPages (int pageOffset)

Read 4 pages (16 bytes).

The MIFARE Ultralight protocol always reads 4 pages at a time, to reduce the number of commands required to read an entire tag.

If a read spans past the last readable block, then the tag will return pages that have been wrapped back to the first blocks. MIFARE Ultralight tags have readable blocks 0x00 through 0x0F. So a read to block offset 0x0E would return blocks 0x0E, 0x0F, 0x00, 0x01. MIFARE Ultralight C tags have readable blocks 0x00 through 0x2B. So a read to block 0x2A would return blocks 0x2A, 0x2B, 0x00, 0x01.

This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
pageOffset index of first page to read, starting from 0
Returns
  • 4 pages (16 bytes)
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled

public void setTimeout (int timeout)

Set the transceive(byte[]) timeout in milliseconds.

The timeout only applies to transceive(byte[]) on this object, and is reset to a default value when close() is called.

Setting a longer timeout may be useful when performing transactions that require a long processing time on the tag such as key generation.

Requires the NFC permission.

Parameters
timeout timeout value in milliseconds

public byte[] transceive (byte[] data)

Send raw NfcA data to a tag and receive the response.

This is equivalent to connecting to this tag via NfcA and calling transceive(byte[]) . Note that all MIFARE Classic tags are based on NfcA technology.

Use getMaxTransceiveLength() to retrieve the maximum number of bytes that can be sent with transceive(byte[]) .

This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with IOException if close() is called from another thread.

Requires the NFC permission.

Throws
IOException
See Also

public void writePage (int pageOffset, byte[] data)

Write 1 page (4 bytes).

The MIFARE Ultralight protocol always writes 1 page at a time, to minimize EEPROM write cycles.

This is an I/O operation and will block until complete. It must not be called from the main application thread. A blocked call will be canceled with IOException if close() is called from another thread.

Requires the NFC permission.

Parameters
pageOffset index of page to write, starting from 0
data 4 bytes to write
Throws
TagLostException if the tag leaves the field
IOException if there is an I/O failure, or the operation is canceled