R1EX24256BSAS0A_12 Datasheet, PDF (8/18 Pages) Renesas Technology Corp – Two-wire serial interface 256k EEPROM (32-kword 8-bit)

R1EX24256BSAS0A/R1EX24256BTAS0A
Device Addressing
The EEPROM device requires an 8-bit device address word following a start condition to enable the chip for a read or a
write operation. The device address word consists of 4-bit device code, 3-bit device address code and 1-bit
read/write(R/W) code. The most significant 4-bit of the device address word are used to distinguish device type and
this EEPROM uses “1010” fixed code. The device address word is followed by the 3-bit device address code in the
order of A2, A1, A0. The device address code selects one device out of all devices which are connected to the bus.
This means that the device is selected if the inputted 3-bit device address code is equal to the corresponding hard-wired
A2-A0 pin status. The eighth bit of the device address word is the read/write(R/W) bit. A write operation is initiated if
this bit is low and a read operation is initiated if this bit is high. Upon a compare of the device address word, the
EEPROM enters the read or write operation after outputting the zero as an acknowledge. The EEPROM turns to a
stand-by state if the device code is not “1010” or device address code doesn’t coincide with status of the correspond
hard-wired device address pins A0 to A2.
Device Address Word
Device address word (8-bit)
Device code (fixed)
Device address code
256k
1
0
1
0
A2
A1
A0
Note: 1. R/W=“1” is read and R/W = “0” is write.
R/W code*¹
R/W
R10DS0005EJ0101 Rev.1.01
Jul. 26, 2012
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