Operation
MOTOROLA
Real-Time Clock (RTC)
23-3
23.1.2 Alarm
There are three alarm registers that mirror the three counter registers. An alarm is set by accessing the
real-time clock alarm registers (ALRM_HM, ALRM_SEC, and DAYALARM) and loading the exact time
that the alarm should generate an interrupt. When the TOD clock value and the alarm value coincide, if the
ALM bit in the real-time clock interrupt enable register (RTCIENR) is set, an interrupt occurs.
NOTE:
If the alarm is not disabled, it will reoccur every 512 days. If a single alarm
is desired, the alarm function must be disabled through the RTC Interrupt
Enable register (RTCIENR).
23.1.3 Sampling Timer
The sampling timer is designed to support application software. The sampling timer generates a periodic
interrupt with the frequency specified by the SAMx bits of the RTCIENR register. This timer can be used
for digitizer sampling, keyboard debouncing, or communication polling. The sampling timer operates only
if the real-time clock is enabled. Table 23-1 lists the interrupt frequencies of the sampling timer for the
possible reference clocks.
Multiple SAMx bits may be set in the RTC Interrupt Enable Register (RTCIENR). The corresponding bits
in the RTC Interrupt Status Register (RTCISR) will be set at the noted frequencies.
23.1.4 Minute Stopwatch
The minute stopwatch performs a countdown with a one minute resolution. It can be used to generate an
interrupt on a minute boundary—for example, to turn off the LCD controller after five minutes of
inactivity, program a value of 0x04 into the Stopwatch Count (CNT) field of the Stopwatch Minutes
(STPWCH) register (see Table 23-12 on page 23-15 for a complete list of settings for the STPWCH
register). At each minute, the value in the stopwatch is decremented. When the stopwatch value reaches -1,
the interrupt occurs. The value of the register does not change until it is reprogrammed. Note that the actual
delay includes the seconds from setting the stopwatch to the next minute tick.
Table 23-1. Sampling Timer Frequencies
Sampling
Frequency
32.768 kHz
Reference Clock
32 kHz
Reference Clock
38.4 kHz
Reference Clock
SAM7
512 Hz
500 Hz
600 Hz
SAM6
256 Hz
250 Hz
300 Hz
SAM5
128 Hz
125 Hz
150 Hz
SAM4
64 Hz
62.5 Hz
75 Hz
SAM3
32 Hz
31.25 Hz
37.5 Hz
SAM2
16 Hz
15.625 Hz
18.75 Hz
SAM1
8 Hz
7.8125 Hz
9.375 Hz
SAM0
4 Hz
3.90625 Hz
4.6875 Hz
Содержание DragonBall MC9328MX1
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Страница 272: ...13 32 MC9328MX1 Reference Manual MOTOROLA DMA Controller ...
Страница 281: ...Programming Model MOTOROLA Watchdog Timer Module 14 9 ...
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Страница 300: ...15 18 MC9328MX1 Reference Manual MOTOROLA Analog Signal Processor ASP ...
Страница 438: ...18 16 MC9328MX1 Reference Manual MOTOROLA Serial Peripheral Interface Modules SPI 1 and SPI 2 ...
Страница 478: ...19 40 MC9328MX1 Reference Manual MOTOROLA LCD Controller ...
Страница 542: ...20 64 MC9328MX1 Reference Manual MOTOROLA Multimedia Card Secure Digital Host Controller Module MMC SD ...
Страница 574: ...21 32 MC9328MX1 Reference Manual MOTOROLA Memory Stick Host Controller MSHC Module ...
Страница 598: ...23 16 MC9328MX1 Reference Manual MOTOROLA Real Time Clock RTC ...
Страница 670: ...24 72 MC9328MX1 Reference Manual MOTOROLA SDRAM Memory Controller ...
Страница 726: ...25 56 MC9328MX1 Reference Manual MOTOROLA SmartCard Interface Module SIM ...
Страница 736: ...26 10 MC9328MX1 Reference Manual MOTOROLA General Purpose Timers ...
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Страница 900: ...30 46 MC9328MX1 Reference Manual MOTOROLA Synchronous Serial Interface SSI ...
Страница 942: ...32 26 MC9328MX1 Reference Manual MOTOROLA GPIO Module and I O Multiplexer IOMUX ...