Datasheet

Lock Bytes (Page 2)

Bytes 2 and 3 of page 2 are referred to as "Lock Bytes". Each page from 0x03 and higher can individually locked by

setting the corresponding locking bit to "1" to prevent further write access, effectively making the memory read only.

For more information on the lock byte mechanism, refer to section 8.5.2 of the datasheet (referenced above).

OTP Bytes (Page 3)

Page 3 is the OTP memory, and by default all bits on this page are set to 0. These bits can be bitwise modified using

the MiFare WRITE command, and individual bits can be set to 1, but can not be changed back to 0.

Data Pages (Page 4-15)

Pages 4 to 15 are can be freely read from and written to, provided there is no conflict with the Lock Bytes described

above.

After production, the bytes have the following default values:

Accessing Data Blocks

In order to access the cards, you must following two steps:

1. 'Connect' to a Mifare Ultralight card and retrieve the 7 byte UID of the card.

2. Memory can be read and written directly once a passive mode connection has been made. No authentication is

required for Mifare Ultralight cards.

Read/Write Lengths

For compatability reasons, "Read" requests to a Mifare Ultralight card will retrieve 16 bytes (4 pages) at a time (which

Page Block 0 Block 1 Block 2 Block 3

----- ---------------------------------------

0 [ Serial Number ]

1 [ Serial Number ]

2 [Serial] - [Intern] - [ Lock Bytes ]

3 [ One Time Programmable Memory ]

4 [ User Data ]

5 [ User Data ]

6 [ User Data ]

7 [ User Data ]

8 [ User Data ]

9 [ User Data ]

10 [ User Data ]

11 [ User Data ]

12 [ User Data ]

13 [ User Data ]

14 [ User Data ]

15 [ User Data ]

Page Byte Values

---- ----------------------

0 1 2 3

4 0xFF 0xFF 0xFF 0xFF

5..15 0x00 0x00 0x00 0x00