Motorola MC68VZ328 - Manual (Page 220)

11-10 MC68VZ328 User’s Manual
Programming Model
11.2.6 RTC Control Register
The real-time clock control (RTCCTL) register is used to enable the real-time clock and provide reference
frequency information to the prescaler. The settings for the RTCCTL register are described in Table 11-7.
RTCCTL RTC Control Register 0x(ff)FFFB0C
11.2.7 RTC Interrupt Status Register
The real-time clock interrupt status register (RTCISR) indicates the status of the various real-time clock
interrupts. Each bit is set when the corresponding event occurs. You must clear these bits by writing ones,
which also clears the interrupt. This register can post interrupts while the system clock is idle or in sleep
mode. The settings for the RTCISR register are described in Table 11-8 on page 11-11. For more
information about the frequency of the RTC interrupts, refer to Table 11-9 on page 11-12.
BIT
15
14 13 12 11 10 9 8 7 6 5 4 3 2 1
BIT
0
RTCEN REFREQ
TYPE rw rw
RESET
0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0
0x0080
Table 11-7. RTC Control Register Description
Name Description Setting
Reserved
Bits 15–8 Reserved These bits are reserved and should be set to
0.
RTCEN
Bit 7 Real-Time Clock Enable—This bit, when set,
enables the real-time clock. 0 = Disable the real-time clock
1 = Enable the real-time clock (default)
Reserved
Bit 6 Reserved This bit is reserved and should be set to 0.
REFREQ
Bit 5 Reference Frequency—This bit is set to the fre-
quency of the crystal oscillator. 0 = Reference frequency is 32.768 kHz
(default).
1 = Reference frequency is 38.4 kHz.
Reserved
Bits 4–0 Reserved These bits are reserved and should be set to
0.