R2025S/D
Typical Software-based Operations
• Initialization at Power-on
Start
*1)
Power-on
*2)
No
PON=1?
*3)
VDET=0?
Yes
Yes
*4)
Set
Control Register 1 and 2,
etc.
No
Warning Back-up
Battery Run-down
*1) After power-on from 0 volt, the start of oscillation and the process of internal initialization require a time
span on the order of 1 to 2sec, so that access should be done after the lapse of this time span or more.
*2) The PON bit setting of 0 in the Control Register 1 indicates power-on from backup battery and not from 0v.
For further details, see "P.31 Power-on Reset, Oscillation Halt Sensing, and Supply Voltage Monitoring
PON, /XST, and VDET ".
•
*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, etc.
• Writing of Time and Calendar Data
*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 "P.27 Data Transmission under Special
Condition".
*1)
*2) Any writing to the second counter will reset divider units lower than the
Start Condition
second digits.
*3) Please see “P,28 The Necessity for Correction of Time Count
*2)
Deviations”
Write to Time Counter and
*4) Take care so that process from Start Condition to Stop Condition will be
Calendar Counter
complete within 0.5sec. (Detailed in "P.27 Data Transmission under
Special Condition".
Write to Clock Adjustment *3)
The R2025S/D may also be initialized not at power-on but in the process
of writing time and calendar data.
Register
*4)
Stop Condition
42
RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
