
Functional Controller Registers
MC68HC08LK60 MC68HC908LK60 Advance Information Data Sheet, Rev. 1.1
Freescale Semiconductor
103
NOTE
When a periodic interrupt of 4 Hz is selected, the periodic interrupt will vary
from 5 Hz to 3.3 Hz with an average of 4 Hz.
8.8.3 RTC Status Register
The RTC status register (RTCSR) is a read-only register containing six status bits. See
Figure 8-6.PRQF — Periodic interrupt flag
PRQF is a status bit indicating that the 1 Hz, 2 Hz, or 4 Hz interval has elapsed. When a a periodic
interrupt of 4 Hz is selected, the periodic interrupt will vary from 5 Hz to 3.3 Hz with an average of 4 Hz.
Reset clears PRQF. A CPU interrupt will be generated if the PRQ1 and PRQ0 bits are set in the
RTCCR.
0 = Flag cleared by a read of the RTC Status Register with the PRQF flag set, followed by a read
of the RTC control register. Both read operations need not be consecutive.
1 = Flag automatically set at 1 Hz, 2 Hz, or 4 Hz intervals. When a a periodic interrupt of 4 Hz is
selected, the periodic interrupt will vary from 5 Hz to 3.3 Hz with an average of 4 Hz.
HORF — Hours flag
HORF is a status bit indicating that the hours counter has rolled over. Reset clears HORF. A CPU
interrupt will be generated if the HRIE bit is set in the RTCCR.
0 = Flag cleared by a read of the RTC status register with the HORF flag set, followed by a read of
the hours register. Both read operations need not be consecutive.
1 = Flag automatically set at 1-hour intervals
MINF — Minutes flag
MINF is a status bit indicating that the minutes counter 1 has rolled over. Reset clears MINF. A CPU
interrupt will be generated if the MINIE bit is set in the RTCCR.
0 = Flag cleared by a read of the RTC status register with the MINF flag set, followed by a read of
the minutes register. Both read operations need not be consecutive.
1 = Flag automatically set at 1-minute intervals
Table 8-3. PRQ1 and PRQ0 RTC Interrupt Periods
PRQ1 and PRQ0
RTC interrupt period
00
RTC interrupt is disabled.
01
RTC interrupt is 1 Hz.
10
RTC interrupt is 2 Hz.
11
RTC interrupt is 4 Hz.
Address:
$0037
Bit 7
654321
Bit 0
Read:
0
PRQF
HORF
MINF
SECF
AFLG
CHRF
Write:
Reset:
00000000
= Unimplemented
Figure 8-6. RTC Status Register (RTCSR)