
RS5C316A/B
18
4. Write Data (For the RS5C316B)
Writing data to the real-time clock requires inputting setting data (control bits, address bits and data bits) to the
SIO pin and then establishing the write mode by using a control bit R/W in the same manner as in read operation.
Data bits
D3-D0: Inputs the data bits MSB to LSB in the addressing table describing the functions
4.1 Write Cycle Flow
1. The CE pin is switched from “L” to “H”.
2. Four control bits (with the first bit ignored) and four write address bits are input from the SIO pin. At this time,
control bits R/W and DT are set equally to 0 while a control bit AD is set to 1. (see the SCLK 1A-8A)
3. Four control bits and four bits of data to be written are input in the descending order of their significance.
At this time, control bits R/W and AD are set equally to 0 while a control bit DT is set to 1. (see the SCLK 1B-8B)
4. When write cycle is continued, control bits and address bits are input at the shift clock pulse 1C and later in the
same manner as at the shift clock pulse 1A.
5. At the end of write operation, control bits R/W, AD, and DT are set equally to 0 (at the rising edge of shift clock
pulse 5A and later from the SCLK pin) or the CE pin is switched from “H” to “L” (after tCEH from the rising edge
of the eighth shift clock pulse from the SCLK pin). Following on write cycle, read operation can be performed by
setting control bits in the read mode at the shift clock pulse 1C and later with the CE pin held at “H”.
R/W
AD
DT
A3
A2
A1
A0
R/W
AD
DT
D3
D2
D1
D0
R/W
AD
*
CE
(Internal process)
SCLK
Input to
SIO pin
Output
from SIO
pin
Writing to shift
register
Writing to address
register
Setting of
control bits
End of write
operation
Setting of
control bits
Control bits
Address bits
Control bits
Data bits
(Hiz)
1A
2A
3A
4A
5A
6A
7A
8A
1B
2B
3B
4B
5B
6B
7B
8B
1C
2C
3C
*) In the above figure, the “*” mark indicates arbitrary data; and the diagonally shaded area of CE and SCLK indicates “H” or “L”.
*) Control bits and address bits are described in the previous section on read cycle.