R2023T-E2-F Datasheet, PDF (42/56 Pages) RICOH electronics devices division – 2-wire Serial Interface Real Time Clock IC

R2023x
* R2023K (FFP12) is the discontinued product as of February, 2016.
• Alarm Interrupt
The alarm interrupt circuit is controlled by the enable bits (i.e. the WALE and DALE bits in the Control Register
1) and the flag bits (i.e. the WAFG and DAFG bits in the Control Register 2). The enable bits can be used to
enable this circuit when set to 1 and to disable it when set to 0. When intended for reading, the flag bits can
be used to monitor alarm interrupt signals. When intended for writing, the flag bits will cause no event when
set to 1 and will drive high (disable) the alarm interrupt circuit when set to 0.
The enable bits will not be affected even when the flag bits are set to 0. In this event, therefore, the alarm
interrupt circuit will continue to function until it is driven low (enabled) upon the next occurrence of a match
between current time and preset alarm time.
The alarm function can be set by presetting desired alarm time in the alarm registers (the Alarm_W Registers
for the day-of-week digit settings and both the Alarm_W Registers and the Alarm_D Registers for the hour and
minute digit settings) with the WALE and DALE bits once set to 0 and then to 1 in the Control Register 1.
Note that the WALE and DALE bits should be once set to 0 in order to disable the alarm interrupt circuit upon
the coincidental occurrence of a match between current time and preset alarm time in the process of setting
the alarm function.
Interval (1min.) during which a match
between current time and preset alarm time
occurs
INTRB
(INTRA)
WALE←1 current time =
WALE←0
WALE←1
(DALE) preset alarm time (DALE)
(DALE)
INTRB
(INTRA)
WALE←1 current time =
(DALE) preset alarm time
WAFG←0
(DAFG)
current time =
preset alarm time
current time =
preset alarm time
After setting WALE(DALW) to 0, Alarm registers is set to current time, and WALE(DALE) is set to 1, INTRB
or INTRA will be not driven to “L” immediately, INTRB or INTRA will be driven to “L” at next alarm setting
time.
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