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AT24CS01_14 Datasheet, PDF (10/23 Pages) ATMEL Corporation – Factory Programmed 128-bit Serial Number
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8. Device Addressing
Standard EEPROM Access: The 1K and 2K EEPROM device requires an 8-bit device address word following
a Start condition to enable the chip for a read or write operation.
The device address word consists of a mandatory ‘1010’ (Ah) sequence for the first four most significant bits
as shown in Figure 8-1. This is common to all Serial EEPROM devices.
The next three bits are the A2, A1, and A0 device address bits for the 1K and 2K EEPROM. These three bits
must compare to their corresponding hard-wired input pins A2, A1, and A0 in order for the part to acknowledge.
The eighth bit of the device address is the read/write operation select bit. A read operation is initiated if this bit is
high and a write operation is initiated if this bit is low.
Upon a valid compare of the device address with hard-wired input pins A2, A1, and A0, the EEPROM will output
a zero. If a compare is not successfully made, the chip will return to a standby state.
Serial Number Access: The AT24CS01 and AT24CS02 utilizes a separate memory block containing a factory
programmed 128-bit serial number. Access to this memory location is obtained by beginning the device address
word with a ‘1011’ (Bh) sequence.
The behavior of the next three bits (A2, A1, and A0) remain the same as during a standard EEPROM
addressing sequence. These three bits must compare to their corresponding hard-wired input pins A2, A1, and
A0 in order for the part to acknowledge.
The eighth bit of the device address needs be set to a one to read the Serial Number. A zero in this bit position,
other than during a dummy write sequence to set the address pointer, will result in a unknown data read from
the part. Writing or altering the 128-bit serial number is not possible.
Further specific protocol is needed to read the serial number from of the device. See Section 10., “Read
Operations” on page 12 for more details on accessing the special feature.
Figure 8-1. Device Address
Density
1K
2K
Access Area
EEPROM
Serial Number
EEPROM
Serial Number
Bit 7
1
1
1
1
MSB
Bit 6
0
0
0
0
Bit 5
1
1
1
1
Bit 4
0
1
0
1
Bit 3
A2
A2
A2
A2
Bit 2
A1
A1
A1
A1
Bit 1
A0
A0
A0
A0
Bit 0
R/W
1
R/W
1
LSB
10 AT24CS01/02 [DATASHEET]
Atmel-8815D-SEEPROM-AT24CS01-02-Datasheet_082014
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