RV5C339A_03 Datasheet, PDF (45/46 Pages) RICOH electronics devices division – 3-WIRE SERIAL INTERFACE REAL-TIME CLOCK IC WITH VOLTAGE MONITORING FUNCTION

RV5C339A
8.3-3 Applied Process of Reading Time and Calendar Data Synchronized with Periodic Interrupt Function
Time data need not be read from all the time counters when used for such ordinary purposes as time count
indication. This applied process can be used to read time and calendar data with substantial reductions in the load
involved in such reading.
For Time Indication in “Day-of-month, Day-of-week, Hour,
Minute, and Second” Format:
Write “×,×,×,×,0,1,0,0”
to control Register 1
Write “×,1,×,1,×,0,1,1”
*¹
to Control Register 2
Generate Interrupt to CPU
NO
CTFG=1?
YES
*² _NO
Second Digit=00?
YES
Read Minute, Hour, Day-of-week,
and Day-of-month Counters
Other Interrupt
Processes
*³
Use Previous Minute,
Hour, Day-of-week,
and Day-of-month Data
Write “×,1,×,1,×,0,1,1”
to Control Register 2
*⁴
*^{1) This step is intended to select the level mode as a waveform mode for the periodic interrupt function.}
*^{2) If this step is completed within 1 second, the step of waiting described in “8.3-1 Ordinary Process of Reading Time and Calendar Data” above need not be}
conducted. This step is detailed in “1.5 Considerations in Reading and Writing Time Data”.
*^{3) This step is intended to read time data from all the time counters only in the first session of reading time data after writing time data.}
*^{4) This step is intended to set the CTFG bit to 0 in the control register 2 to cancel an interrupt to the CPU.}
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