Datasheet

Section 19 EEPROM
Rev.5.00 Nov. 02, 2005 Page 357 of 500
REJ09B0027-0500
In case the EEPROM has accessed the last address H'01FF at previous read operation, the
current address will roll over and returns to zero address. In case the EEPROM has accessed
the last address of the page at previous write operation, the current address will roll over within
page addressing and returns to the first address in the same page.
The current address is valid while power is on. The current address after power on will be
undefined. After power is turned on, define the address by the random address read operation
described below is necessary.
The current address read operation is shown in figure 19.5.
SDA
D7
D0
R/W ACK
SCL
ACK
1123456789 8
9
Start
condition
Stop
conditon
[Legend]
R/W: R/W code (0 is for a write and 1 is for a read)
ACK: acknowledge
Read Data
Slave address
Figure 19.5 Current Address Read Operation
2. Random Address Read
This is a read operation with defined read address. A random address read requires a dummy
write to set read address. The EEPROM receives a start condition, slave address + R/W code
(R/W = 0), memory address (upper) and memory address (lower) sequentially. The EEPROM
outputs acknowledgement "0" after receiving memory address (lower) then enters a current
address read with receiving a start condition again. The EEPROM outputs the read data of the
address which was defined in the dummy write operation. After receiving acknowledgement
"1" and a following stop condition, the EEPROM stops the random read operation and returns
to a standby state.
The random address read operation is shown in figure 19.6.