3-WIRE REAL-TIME CLOCK
S-35190A
Rev.2.4_00
Serial Interface
The S-35190A receives various commands via 3-wire serial interface to Read/Write data. Regarding transmission is as
follows.
1. Data Read
When data is input from the SIO pin in synchronization with the falling of the SCK clock after setting the CS pin to “H”, the
data is loaded internally in synchronization with the next rising of the SCK clock. When R / W bit = “1” is loaded at the
eighth rising of the SCK clock, the state of data reading is entered. Data corresponding to each command is then output
in synchronization with the falling of the subsequent SCK clock input. When the SCK clock is less than 8, the IC is in
the clock-wait status, and no processing is performed.
2. Data Write
When data is input from the SIO pin in synchronization with the falling of the SCK clock after setting the CS pin to “H”, the
data is loaded internally in synchronization with the next rising of the SCK clock. When R / W bit = “0” is loaded at the
eighth rising of the SCK clock, the state of data writing is entered. In this state, the data, which is input in synchronization
with the falling of the subsequent SCK clock input, is written to registers according to each command. In data Write, input
a clock pulse which is equivalent to the byte of the register. As well as in Read, when the SCK clock is less than 8, the IC
is in the clock-wait status, and no processing is performed.
3. Data access
(1) Real-time data 1 access
CS
8
56
1
16
64
SCK
SIO
R / W
X
0 1 1 0 0 1 0
B7
B0
B7
B0
Year data
Second data
Fixed code +
command
During reading:
During reading: Output mode switching
Figure 34 Real-Time Data Access 1
30
Seiko Instruments Inc.
SII [ SEIKO INSTRUMENTS INC ]
