2-WIRE CMOS SERIAL E2PROM
S-24CS01A/02A/04A/08A
Rev.4.4_00
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 VAH.
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. However, the page address (P0) in S-
24CS04A and the page address (P1 and P0) in S-24CS08A become invalid and the memory address of
the current address pointer becomes valid.
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.
NO ACK from
Master Device
S
T
A
R
T
R
E
A
D
S
T
DEVICE
O
P
ADDRESS
A0
A1
1
0
1
0 A2
1
SDA LINE
D7 D6 D5 D4 D3 D2 D1 D0
DATA
M
S
B
L R
A
C
K
/
W
S
B
ADR INC
Remark1. A1 is P1 in S-24CS08A.
2. A0 is P0 in S-24CS04A/08A.
Figure 16 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 bits of the memory address (the upper bits of the word address and page address)*1 are left
unchanged and are not incremented at the falling edge of the SCL clock for the 8th bit of the received
data.
*1. S-24CS01A/02A is the upper 5 bits of the word address.
S-24CS04A is the upper 4 bits of the word address and the page address P0.
S-24CS08A is the upper 4 bits of the word address and the page address P1 and P0.
16
Seiko Instruments Inc.
SII [ SEIKO INSTRUMENTS INC ]
