RTC_IER field descriptions (continued)
Field Description
0 Seconds interrupt is disabled.
1 Seconds interrupt is enabled.
3
Reserved
This field is reserved.
2
TAIE
Time Alarm Interrupt Enable
0 Time alarm flag does not generate an interrupt.
1 Time alarm flag does generate an interrupt.
1
TOIE
Time Overflow Interrupt Enable
0 Time overflow flag does not generate an interrupt.
1 Time overflow flag does generate an interrupt.
0
TIIE
Time Invalid Interrupt Enable
0 Time invalid flag does not generate an interrupt.
1 Time invalid flag does generate an interrupt.
34.3 Functional description
34.3.1 Power, clocking, and reset
The RTC is an always powered block that remains active in all low power modes.
The time counter within the RTC is clocked by a 32.768 kHz clock sourced from an
external crystal using the oscillator.
The power-on-reset signal initializes all RTC registers to their default state. A software
reset bit can also initialize all RTC registers.
34.3.1.1 Oscillator control
The 32.768 kHz crystal oscillator is disabled at POR and must be enabled by software.
After enabling the cystal oscillator, wait the oscillator startup time before setting
SR[TCE] or using the oscillator clock external to the RTC.
The crystal oscillator includes tunable capacitors that can be configured by software. Do
not change the capacitance unless the oscillator is disabled.
Functional description
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
606 Freescale Semiconductor, Inc.
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