BR24G256-3 Datasheet, PDF (17/33 Pages) Rohm – Serial EEPROM Series Standard EEPROM

BR24G256-3
Datasheet
WP Valid Timing (Write Cancel)
WP is usually fixed to 'H' or 'L', but when WP is used to cancel write cycle and so on, pay attention to the following WP valid
timing. During write cycle execution, inside cancel valid area, by setting WP='H', write cycle can be cancelled. In both byte
write cycle and page write cycle, the area from the first start condition of command to the rise of clock to take in D0 of
data(in page write cycle, the first byte data) is the cancel invalid area.
WP input in this area becomes ‘Don't care’. The area from the rise of SCL to take in D0 to the stop condition input is the
cancel valid area. Furthermore, after the execution of forced end by WP, the IC enters standby status.
・Rise of D0 taken clock
SCL
SDA
D1 D0 ACK
Enlarged view
・Rise of SDA
SCL
SDA D0 ACK
Enlarged view
SDA
WP
S
T _Slave
A
R ^Address
T
A
C ^Word
K
L
Address
A
C
K
L
A
D7 D6 D5 D4 D3 D2 D1 D0 _C
K
L
Data
AS
CT
KO
LP
t_WR
WP Cancel Invalid Area
WP Cancel Valid Area WP Cancel Invalid Area
Data is not written.
Figure 42. WP Valid Timing
Command Cancel by Start Condition and Stop Condition
During command input, by continuously inputting start condition and stop condition, command can be cancelled. (Figure
43.) However, within ACK output area and during data read, SDA bus may output 'L'. In this case, start condition and stop
condition cannot be input, so reset is not available. Therefore, execute software reset. When command is cancelled by
start-stop condition during random read cycle, sequential read cycle, or current read cycle, internal setting address is not
determined. Therefore, it is not possible to carry out current read cycle in succession. To carry out read cycle in succession,
carry out random read cycle.
SCL
SDA
1
0
1
0
Start Condition Stop Condition
Figure 43. Case of Cancel by Start, Stop Condition during Slave Address Input
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