Minute Stopwatch - Freescale Semiconductor MCF54455 Reference Manual

28.4.4

Minute Stopwatch

The minute stopwatch performs a countdown with a one minute resolution. It can generate an interrupt on
a minute boundary. For example, to turn off a peripheral after five minutes of inactivity, program a value
of 0x04 into RTC_STPWCH[CNT]. At each minute, the value in the stopwatch decrements. When the
stopwatch value reaches -1, interrupt occurs. The value of the register does not change until it is
reprogrammed. The actual delay includes the seconds from setting the stopwatch to the next minute tick.
28.5 Initialization/Application Information
28.5.1 Flow Chart of RTC Operation
Table 28-14 shows the flow chart of a typical RTC operation.
28.5.2 Programming the Alarm or Time-of-Day Registers
Use the following procedure illustrated in
hour, minute, and second) registers.
Freescale Semiconductor
Apply RTC Oscillator Clock
Configure RTC_GOCU and RTC_GOCL
Configure RTC_CR
Configure RTC_DAYS
Configure RTC_SECONDS
Configure RTC_HOURMIN
Configure RTC Alarm Registers
Configure RTC_IER
Check RTC_ISR
Figure 28-14. Flow Chart of RTC Operation
Figure 28-15 when changing the alarm or time-of-day (day,
Real-Time Clock
28-13