24C32 / 24C64
E
Read Operations
RANDOM READ:
A random read requires a "dummy" byte write sequence to load in the data word address. Once the
device address word and data word address are clocked in and acknowledged by the EEPROM, the microcontroller
must generate another start condition. The microcontroller now initiates a current address read by sending a device
address with the read/write select bit high. The EEPROM acknowledges the device address and serially clocks out the
data word. The microcontroller does not respond with a "0" but does generate a following stop condition (see Figure 8
on page 8).
SEQUENTIAL READ:
Sequential reads are initiated by either a current address read or a random address read. After
the microcontroller receives a data word, it responds with an acknowledge. As long as the EEPROM receives an
acknowledge, it will continue to increment the data word address and serially clock out sequential data words. When
the memory address limit is reached, the data word address will "roll over" and the sequential read will continue. The
sequential read operation is terminated when the microcontroller does not respond with a "0" but does generate a
following stop condition (see Figure 9 on page 8).
¡
Figure 4: Device Address
32K/64K
1
MSB
0
1
0
A2
A1
A0
R/W
LSB
¡
Figure 5: Byte Write
W
S
R
T
I
A
R DEVICE T
T ADDRESS E
SDA LINE
M
S
B
L R AM
S / CS
BWK B
L AM
SCS
B KB
LA
SC
BK
A
C
K
FIRST WORD SECOND WORD
ADDRESS
ADDRESS
DATA
S
T
O
P
¡
Figure 6: Page Write
S
W
T
R
A
I
R DEVICE T
T ADDRESS E
SDA LINE
M
S
B
L R AM
S / CS
BWK B
L AM
SCS
B KB
L
S
B
A
C
K
A
C
K
A
C
K
A
C
K
FIRST WORD SECOND WORD
ADDRESS
ADDRESS
DATA( n )
DATA( n+1 )
DATA( n+x )
S
T
O
P
BEIJING ESTEK ELECTRONICS CO.,LTD
7
ESTEK [ Estek Electronics Co. Ltd ]
