RS5C316A/B
29
Ensure stable oscillation by preventing the following:
1) Condensation on the crystal oscillator
2) Instantaneous disconnection of power
3) Generation of clock noises, etc, in the crystal
oscillator
4) Charge of voltage exceeding prescribed maxi-
mum ratings to the individual pins of the IC
13. Typical Software-based Operations
13.1 Initialization upon Power-on
13.2 Write Operation to Clock and Calendar Counters
Start
XSTP=0?
BSY=0?
Interrupt cycle register
←0h
Control register 2
←3h
(BANK
←1)
10-hour alarm register
←0h
(ALE
←0)
Control register 1
←3h
Control register 2
←1h, 9h
Set clock and calendar
counters and interrupt cycles.
Wait or
other
operations.
Power-on
YES
NO
YES
NO
*1
*2
*3
*4
*6
*5
BSY=0?
Write to clock and
calendar counters.
CE=L
Wait or
other
operations.
CE=L
Control register 1
←0h
CE=H
YES
NO
*1
*2
*3
*4
*1) Switch the CE pin to the low level immediately after power-on.
*2) When not making oscillation halt sensing (data validity), the XSTP bit
need not be checked.
*3) Turn off the INTR pin, whose output is uncertain at power-on.
*4) Set the ADJ bit to 1. When writing control register 1, if the oscillator has
operated, the XSTP bit is changed from 1 to 0.
*5) It takes about 0.1 to 2 seconds to be set the BSY bit to 0 from oscillation
starting upon power-on from 0V. Provide an exit from an oscillation start
loop to prepare for oscillation failure.
*6) Set the XSTP bit to 0 by writing data to the control register 1, and set to
the control register 2,
0h for the 12-hour time display system.
4h for the 24-hour time display system.
*1) After switching the CE pin to the high level, hold it at the high level until
any subsequent operation requires switching it to the low level. (Note
that switching the CE pin to the low level sets the WTEN bit to 1.)
*2) WTEN bit is set to 0.
*3) The BSY bit is held at 1 for a maximum duration of 122.1s.
*4) Switch the CE pin to the low level to set the WTEN bit to 1. During write
operation to the clock and calendar counters, one 1-second digit carry
causes a 1-second increment while two 1-second digit carries also cause
only a 1-seconds increment, which, in turn, causes a time delay.
When Using the XSTP Bit