Texas Instruments MSP430x4xx Family, User Manual

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Real-Time Clock Operation
14-6 Real Time Clock
14.2.4 Real-Time Clock Interrupts
The Real-Time Clock uses two bits for interrupt control.
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Basic Timer1 interrupt flag, BTIFG, located in IFG2.7
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Real-Time Clock interrupt enable, RTCIE, located in the module
The Real-Time Clock module shares the Basic Timer1 interrupt flag and
vector. When RTCIE = 0, the Basic Timer1 controls interrupt generation with
the BTIPx bits. In this case, the RTCEVx bits select the interval for setting the
RTCFG flag, but the RTCFG flag does not generate an interrupt. The RTCFG
flag must be cleared with software when RTCIE = 0.
When RTCIE = 1, the RTC controls interrupt generation and the Basic Timer1
BTIPx bits are ignored. In this case, the RTCFG and BTIFG flags are set at the
interval selected with the RTCEVx bits, and an interrupt request is generated
if the GIE bit is set. Both the RTCFG and BTIFG flags are reset automatically
when the interrupt is serviced, or can be reset with software.
The interrupt intervals are listed in Table 14−1.
Table 14−1.RTC Interrupt Intervals
RTC Mode RTCTEVx Interrupt Interval
Counter Mode 00 8-bit overflow
01 16-bit overflow
10 24-bit overflow
11 32-bit overflow
Calendar Mode 00 Minute changed
01 Hour changed
10 Every day at midnight (00:00)
11 Every day at noon (12:00)