S-24CS64A Datasheet, PDF (15/44 Pages) Seiko Instruments Inc – 2-WIRE CMOS SERIAL E2PROM

Rev.3.3_00
2-WIRE CMOS SERIAL E²PROM
S-24CS64A
7. Read
7.1 Current Address Read
Either in writing or in reading the E²PROM holds the last accessed memory address, internally
incremented by one. The memory address is maintained as long as the power voltage is higher than the
current address hold voltage V_AH.
The master device can read the data at the memory address of the current address pointer without
assigning the word address as a result, when it recognizes the position of the address pointer in the
E²PROM. This is called “Current Address Read”.
In the following the address counter in the E²PROM is assumed to be “n”.
When the E²PROM receives a 7-bit device address and a 1-bit read / write instruction code set to “1”
following a start condition, it responds with an acknowledge.
Next an 8-bit data at the address “n” is sent from the E²PROM synchronous to the SCL clock. The
address counter is incremented at the falling edge of the SCL clock for the 8th bit data, and the content of
the address counter becomes n+1.
The master device outputs stop condition not an acknowledge, the reading of E²PROM is ended.
S
NO ACK from
T
R
Master Device
S
A
R
T
E
DEVICE
A
ADDRESS
D
T
O
P
SDA LINE
1 0 1 0 A2 A1 A0 1 D7 D6 D5 D4 D3 D2 D1 D0
M
LR A
DATA
S
S/ C
B
BW K
ADR INC
Figure 15 Current Address Read
Attention should be paid to the following point on the recognition of the address pointer in the E²PROM.
In the read operation the memory address counter in the E²PROM is automatically incremented at every
falling edge of the SCL clock for the 8th bit of the output data. In the write operation, on the other hand,
the upper 8 bits of the memory address are left unchanged and are not incremented at the falling edge of
the SCL clock for the 8th bit of the received data.
Seiko Instruments Inc.
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