RV5C387A_03 Datasheet, PDF (46/49 Pages) RICOH electronics devices division – I2C bus SERIAL INTERFACE REAL-TIME CLOCK IC WITH VOLTAGE MONITORING FUNCTION

RV5C387A
8. Typical Software-based Operations
8.1 Initialization at Power-on
Start
*¹
Power-on
XSTP=1?
*^{2 NO}
YES
*⁴
Set Oscillation Adjustment Register
and Control Registers 1 and 2, etc.
*³
NO
VDET=0?
YES
Warning of Backup Battery
Run-down
*1) After power-on from 0 volts, the start of oscillation and the process of internal initialization require a time span on the order of 1 to 2 seconds, so that
access should be done after the lapse of this time span or more.
*2) The XSTP bit setting of 0 in the control register 1 indicates power-on from backup battery and not from 0 volt. The XSTP bit may fail to be set to 1 in the
presence of any excessive chattering in power supply in such events as installing backup battery. Should there be any possibility of this failure occurring,
it is recommended to initialize the RV5C387A regardless of the current XSTP bit setting. For further details, see “3. Oscillation Halt Sensing and Supply
Voltage Monitoring”.
*^{3) This step is not required when the supply voltage monitoring circuit is not used.}
*^{4) This step involves ordinary initialization including the oscillation adjustment register and interrupt cycle settings.}
8.2 Writing of Time and Calendar Data
Start condition
*¹
Write to clock and
calendar counters
*²
Stop condition
*³
*1) When writing to clock and calendar counters, do not insert stop condition
until all times from second to year have been written to prevent error in
writing time. (Detailed in “1.2-6 Data transmission under special
condition”.
*2) Any writing to the second counter will reset divider units lower than the
second digits.
*3) Take care so that process from start condition to stop condition will be
complete within 0.5sec. (Detailed in “1.2-6 Data transmission under
special condition”.
The RV5C387A may also be initialized not at power-on but in the process
of writing time and calendar data.
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