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PN532-RFID-NFC-Carte-et-tag-MiFare (voir la source)
Version du 31 juillet 2015 à 10:52
, 31 juillet 2015 à 10:52→Cartes MiFare Ultralight
14 [ User Data ]
14 [ User Data ]
15 [ User Data ]</nowiki>
15 [ User Data ]</nowiki>
=== Lock Bytes (page 2) ===
Lock Bytes sont les octets de blocage. Pour rappel, un ''Byte'' (''anglais'') est un ''octet'' (Français) et contient 8 bits.
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) ===
OTP Bytes signifie "One Time Programming Bytes" et représente des octets qui ne peuvent être écrit qu'une seule fois.
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.
=== Pages de données (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:
<nowiki> Page Byte Values
---- ----------------------
0 1 2 3
4 0xFF 0xFF 0xFF 0xFF
5..15 0x00 0x00 0x00 0x00</nowiki>
=== Accès aux blocs de données ===
In order to access the cards, you must following two steps:
# 'Connect' to a Mifare Ultralight card and retrieve the 7 byte UID of the card.
# Memory can be read and written directly once a passive mode connection has been made. No authentication is required for Mifare Ultralight cards.
=== Longueur Lecture/Ecriture ===
For compatability reasons, "Read" requests to a Mifare Ultralight card will retrieve 16 bytes (4 pages) at a time (which corresponds to block size of a Mifare Classic card). For example, if you specify that you want to read page 3, in reality pages 3, 4, 5 and 6 will be read and returned, and you can simply discard the last 12 bytes if they aren't needed. If you select a higher page, the 16 byte read will wrap over to page 0. For example, reading page 14 will actually return page 14, 15, 0 and 1.
"Write" requests occur in pages (4 bytes), so there is no problem with overwriting data on subsequent pages.
{{PN532-RFID-NFC-TRAILER}}
{{PN532-RFID-NFC-TRAILER}}