MC68HC908LJ24 Datasheet, PDF (227/464 Pages) Motorola, Inc – Microcontrollers

Freescale Semiconductor, Inc.
Real Time Clock (RTC)
RTC Register and Bit Write Protection
TRUE 15 SECONDS
CGMXCLK
UNCOMPENSATED
1-Hz CLOCK
(CGMXCLK ÷ 32768)
COMPENSATED
1-Hz CLOCK
PERIOD A
1-Hz CLOCK = CGMXCLK ÷ A
PERIOD B
1-Hz CLOCK = CGMXCLK ÷ B
Figure 12-4. 1-Hz Clock Compensation
12.8 RTC Register and Bit Write Protection
A write-protect mechanism is implemented to prevent accidental writes
to the RTC clock registers, calendar registers, and other control bits. The
protected RTC registers and bits are listed in Table 12-3.
Table 12-3. Write-Protected RTC Registers and Bits
Register
RTC Control Register 1
RTC Control Register 2
Second Register
Minute Register
Hour Register
Day-Of-Week Register
Day Register
Month Register
Year Register
Bit
CAL
AUTOCAL
OUTF[1:0]
COMEN
RTCE
(All Bits)
(All Bits)
(All Bits)
(All Bits)
(All Bits)
(All Bits)
(All Bits)
MC68HC908LJ24/LK24 — Rev. 2
MOTOROLA
Real Time Clock (RTC)
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Data Sheet
227