24RF08 データシートの表示（PDF） - Atmel Corporation
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24RF08 Datasheet PDF : 21 Pages
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Byte 15 contains device revision information. It is set at the
wafer production facility and cannot be changed in the field,
so any write to this byte will be ignored. The least
significant three bits are used to show the production
revision for the part. The next three bits are used to denote
the option set chosen and the most significant two bits
describe the basic functionality of the device. The value of
this byte is 01 001 001, or 49 (hex).
The memory map for the access protection page is shown
in the table below. In this table, an x means that the value is
a don’t care upon writing and that it is undefined upon
reading. The RF and PB fields are all two bits wide, and the
Device Revision field is 8 bits wide. All other fields are one
bit wide.
APP Memory Map
Address
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Bit 7
SB0
SB1
SB2
SB3
SB4
SB5
SB6
SB7
SBAP
WP7
DE
Bit 6
TW0
TW1
TW2
TW3
TW4
TW5
TW6
TW7
x
WP6
DC
Bit 5
Bit 4
Bit 3
RF0
x
RF1
x
RF2
x
RF3
x
RF4
x
RF5
x
RF6
x
RF7
x
x
x
x
WP5
WP4
WP3
x
x
x
reserved
reserved
reserved
reserved
Device Revision
Bit 2
x
x
x
x
x
x
x
x
x
WP2
x
Bit 1
Bit 0
WP1
PB0
PB1
PB2
PB3
PB4
PB5
PB6
PB7
PBAP
WP0
x
Tamper
With the exception of the 9 sticky bits (SB) and the two coil
detect bits (DE and DC), all bits within the Access
Protection Page are stored in EEPROM memory. Their
state does not change if power is removed or when the
PROT pin is held low.
The following page of memory (accessed with A4 = 1)
contains the ID field transmitted by the device from the
RFID port. Bytes within it are accessed via a device
address byte of B8 / B9 (write / read, hex) and a byte
address of 10 through 1F (hex). Reading and writing to this
ID page is permitted when PBAP is 11. The least significant
three bits of the first byte should vary to optimize multiple
tag performance.
The MSB of the last byte of the ID page is a lock bit that
controls writes to the ID page from the RFID port. If this bit
is a 0, writes to this page from the RFID part are locked out
(prohibited). This bit does not affect operation from the
serial side, and can be read and written to either state
normally from the serial port. The ID page can always be
read from the RFID port.
Please note that neither the RF fields nor the TW bits
protect the ID page against writes from the RFID port.
Unless the ID value is locked using the ID lock bit, the user
can write to the ID page regardless of the state of any
access control bits.
Other than setting the tamper bit via the RFID commands
or reading the ID field when so directed, there is no way for
the RFID port to directly read or write the access protection
page.
6
AT24RF08C
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