S-24CS64A Datasheet, PDF (16/44 Pages) Seiko Instruments Inc – 2-WIRE CMOS SERIAL E2PROM

2-WIRE CMOS SERIAL E²PROM
S-24CS64A
Rev.3.3_00
7.2 Random Read
Random read is used to read the data at an arbitrary memory address.
A dummy write is performed to load the memory address into the address counter.
When the E²PROM receives a 7-bit device address and a 1-bit read / write instruction code set to “0”
following a start condition, it responds with an acknowledge. The E²PROM then receives an 8-bit upper
word address and responds with an acknowledge. Next the E²PROM then receives an 8-bit lower word
address and responds with an acknowledge. The memory address is loaded to the address counter in the
E²PROM by these operations. Reception of write data does not follow in a dummy write whereas reception
of write data follows in a byte write and in a page write.
Since the memory address is loaded into the memory address counter by dummy write, the master device
can read the data starting from the arbitrary memory address by transmitting a new start condition and
performing the same operation in the current address read.
That is, when the E²PROM receives a 7-bit device address and a 1-bit read / write instruction code set to
“1”, following a start condition signal, it responds with an acknowledge. Next, 8-bit data is transmitted
from the E²PROM in synchronous to the SCL clock. The master device outputs stop condition not an
acknowledge, the reading of E²PROM is ended.
S
W
S
T
R
T
R
A
I
A
E
R
DEVICE
T
R
DEVICE
A
T
ADDRESS
E UPPER WORD ADDRESS LOWER WORD ADDRESS _T
ADDRESS
D
NO ACK from
Master Device
S
T
O
DATA
P
SDA
LINE
1 0 1 0 A2 A1 A0 0
XX X X W12W11W10W9 W8 W7 W6 W5 W4 W3 W2 W1 W
1 0 1 0 A2 A1 A0 1 D7 D下6図D5へD続4 くD3 D2 D1 D0
M
LR A
A
S
S/ C
C
B
BW K
K
AM
CS
KB
LR A
S/ C
BW K
ADR INC
DUMMY WRITE
Figure 16 Random Read
16
Seiko Instruments Inc.