Datasheet

Real Time Clock (RTC)
Technical Data MC68HC908LJ12 — Rev. 2.1
220 Real Time Clock (RTC) Freescale Semiconductor
ALMF — Alarm Flag
This clearable, read-only bit is set when the value in the RTC hour and
minute counters matches the value in the alarm hour and alarm
minute registers. When the ALMIE bit in RTCCR1 is set, ALMF
generates a CPU interrupt request. In normal operation, clear the
ALMF bit by reading RTCSR with ALMF set and then reading the
alarm hour register (ALHR). Reset clears ALMF.
1 = RTC hour and minute counters matches the
alarm hour and minute registers
0 = No matching between hour and minute counters and alarm
hour and minute registers
CHRF — Chronograph Flag
This clearable, read-only bit is set on every tick of the chronograph
counter (every counter count). The tick is on every 1/100 or 1/128
seconds (see 12.4.5 Chronograph Functions). When the CHRIE bit
in RTCCR1 is set, CHRF generates a CPU interrupt request. In
normal operation, clear the CHRF bit by reading RTCSR with CHRF
set and then reading the chronograph data register (CHRR). Reset
clears CHRF.
1 = A chronograph counter tick has occurred
0 = No chronograph counter tick has occurred
DAYF — Day Flag
This clearable, read-only bit is set on every increment of the day
counter. When the DAYIE bit in RTCCR1 is set, DAYF generates a
CPU interrupt request. In normal operation, clear the DAYF bit by
reading RTCSR with DAYF set and then reading the day register
(DAYR). Reset clears DAYF.
1 = Day counter incremented
0 = No day counter incremented
HRF — Hour Flag
This clearable, read-only bit is set on every increment of the hour
counter. When the HRIE bit in RTCCR1 is set, HRF generates a CPU
interrupt request. In normal operation, clear the HRF bit by reading
RTCSR with HRF set and then reading the hour register (HRR). Reset
clears HRF.
1 = Hour counter incremented
0 = No hour counter incremented