S-34C02A Datasheet, PDF (18/34 Pages) Seiko Instruments Inc – 2-WIRE CMOS SERIAL E2PROM FOR DIMM SERIAL PRESENCE DETECT

2-WIRE CMOS SERIAL E²PROM FOR DIMM SERIAL PRESENCE DETECT
S-34C02A
Rev.1.2_00
7. 2 Random Read
Random Read is used to read data at an arbitrary memory address.
To load the memory address into an address counter in the S-34C02A, perform Dummy Write with the process
below.
When the S-34C02A receives the 7-bit device address and the Read/Write instruction code “0” after receiving a
start condition, it generates an acknowledgment signal. After that, it generates an acknowledgment signal by
receiving the 8-bit word address. By these operations, the memory address is loaded into the address counter in the
S-34C02A.
After this, in Byte Write and Page Write, the S-34C02A receives Write data, but in Dummy Write, the S-34C02A
does not receive data.
Since the memory address has been loaded into the memory address counter by Dummy Write, the master device
sends a start condition newly and performs the same operation as current Read. The users can read data which
starts from the arbitrary memory address.
Thus, the S-34C02A receives the 7-bit device address and the Read/Write instruction cord “1” after receiving a start
condition, it generates an acknowledgment signal.
And 8-bit data is output from the S-34C02A synchronizing with the SCL clock. After that, the Read operation ends
when the master device transmits a stop condition, not an acknowledgment signal.
S
W
T
R
A
I
S
T
A
R
E
NO ACK from
Master Device
S
T
R
DEVICE
T
R
DEVICE ^A
O
T ADDRESS ^E WORD ADDRESS (n) T
ADDRESS D
DATA
P
SDA
LINE
1 0 1 0 A2 A1 A0 0 _{W7 W6 W5 W4 W3 W2 W1 W0}
1 0 1 0 A2 A1 A0 1 D7 D6 D5 D4 D3 D2 D1 D0
M
LR A
S
S/ C
B
BW K
AM
CS
KB
LR A
S/ C
BW K
ADR INC
DUMMY WRITE
Figure 14 Random Read
18
Seiko Instruments Inc.