pca24s08a NXP Semiconductors, pca24s08a Datasheet - Page 8

• Manufacturer Part Number: pca24s08a
• Description: 1024 ? 8-bit Cmos Eeprom With Access Protection
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA24S08A_1
Product data sheet
Fig 9.
Master read PCA24S08A immediately after first byte (read mode); current address read
6.4.1 RFID access fields (RF)
6.4.2 Protection bits (PB)
6.4 Access protection
S
START condition
1
Write operation on the Access protection registers can be performed when WP pin is
LOW. If the WP pin is HIGH, all write operations are prohibited from the serial port,
although write commands may be used to set the address for a subsequent read
command.
All access protection bits are stored on a separate page of the EEPROM that is not
accessed using the normal commands of a PCA24S08A memory. See
“Access Protection Page (APP)”
Even though the PCA24S08A does not have the RFID capability, RFID access fields (RF)
can be stored in order to keep existing software compatibility. The fields are stored in the
EEPROM and organized as shown in
Table 3.
The protection bits fields in the Access Protection Page determine what type of accesses
will be permitted via the serial port for each of the blocks on the chip. If an illegal access is
attempted, the command will be NACKed. The MSB (if clear) prohibits all access to the
block, and the LSB (if clear) prohibits writes. The fields are stored in the EEPROM and are
organized as shown in
Table 4.
MSB
0
0
1
1
MSB
0
0
1
1
0
1
0
LSB
0
1
0
1
LSB
0
1
0
1
1
RFID access field organization
PB organization
X
X
R/W
Function
no accesses permitted from RFID port
no accesses permitted from RFID port
read only from RFID port
no restrictions for RFID accesses
Function
no accesses permitted in the block
no accesses permitted in the block
read only; writes cause a NACK
read/write; no access constraints for data within this block
1
Rev. 01 — 19 January 2010
A
acknowledge
from slave
Table
4.
n bytes
DATA
for more detail on this information.
1024 × 8-bit CMOS EEPROM with access protection
acknowledge
from master
auto-increment
Table
word address
3.
A
last byte
DATA
no acknowledge
from master
STOP condition
auto-increment
word address
PCA24S08A
A
002aae794
P
Section 6.4.2.2
© NXP B.V. 2010. All rights reserved.
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