S7760A Datasheet, PDF (24/54 Pages) Seiko Instruments Inc – PROGRAMMABLE PORT CONTROLLER (PORT EXPANDER WITH BUILT-IN E2PROM CIRCUIT)

PROGRAMMABLE PORT CONTROLLER (PORT EXPANDER WITH BUILT-IN E²PROM CIRCUIT)
S-7760A
Rev.2.0_01
6. Write operation
6. 1 Write
When this IC receives the 7-bit device address and the Read/Write instruction code “0” after receiving a start condition,
it generates an acknowledgment signal.
Next, after it receives the 8-bit word address and generates an acknowledgment signal, it receives a stop condition to
finish the Write command.
In the Write operation to the E²PROM, the Write operation starts with a stop condition, the S-7760A finishes it after the
period to Write (max. 5 ms) has elapsed. During Write to the E²PROM, all operations are inhibited to be performed
and the S-7760A does not send back any acknowledgment signals for command inputs.
S
W
T
R
A
I
R
T
T
DEVICE
E
ADDRESS
S
T
O
P
DATA
SDA LINE
D DD
C C C C3 C2 C1 C0 0
2 10
B7 B6 B5 B4 B3 B2 B1 B0
M
LR A
S
S/ C
B
BW K
A
C
K
Figure 27 Write
6. 2 Write Protect
Write protect is available in the S-7760A.
When the WP pin is connected to VCCH, the Write operation in all memory area is inhibited. When the WP pin is
connected to GND, Write protect becomes invalid so that the Write operation in all memory area is accepted.
Fix the WP pin during the period; from rising of SCL at installing the last bit in Write data until the completion of Write
period (max. 5 ms).
Written data in the address is not assured if the condition of the WP pin is changed during this period. Be sure to
connect the WP pin to GND when you don’t use Write Protect. Write Protect is valid in the range of power supply
voltage.
t_WR
SCL
SDA
B0
Write Data
WP
Acknowledgment
signal
Stop
Condition
Period to fix WP pin
Figure 28 Period to Fix WP Pin
24
Start
Condition