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6.2.2.4.6
Real-Time Clock Register (RTC)
The real-time clock register is a 32-bit read write register. It contains the current value of
the real-time clock. A write to the RTC resets the seconds timer to zero. This register is
locked after RESET by default. Unlocking is accomplished by writing 0x55CCAA33 to its
associated key register. See Section 8.8.3.2, "Keep-Alive Power Registers Lock
Mechanism."
MSB
0
Field
Reset
Addr
6.2.2.4.7
Real-Time Clock Alarm Register (RTCAL)
The RTCAL is a 32-bit read/write register. When the value of the RTC is equal to the value
programmed in the alarm register, a maskable interrupt is generated.
The alarm interrupt will be generated as soon as there is a match between the ALARM field
and the corresponding bits in the RTC. The resolution of the alarm is 1 second. This register
is locked after RESET by default. Unlocking is accomplished by writing 0x55CCAA33 to
its associated key register. See Section 8.8.3.2, "Keep-Alive Power Registers Lock
Mechanism."
MSB
0
Field
Reset
Addr
Figure 6-37. Real-Time Clock Alarm Register (RTCAL)
6.2.2.4.8
Periodic Interrupt Status and Control Register (PISCR)
The PISCR contains the interrupt request level and the interrupt status bit. It also contains
the controls for the 16-bits to be loaded into a modulus counter. This register can be read or
written at any time.
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
Figure 6-36. Real-Time Clock Register (RTC)
Chapter 6. System Configuration and Protection
Memory Map and Register Definitions
RTC
Unaffected
0x2F C224
ALARM
Unaffected
0x2F C22C
LSB
31
LSB
31
6-45
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