I have a PIC18F47J53 with an RTCC. The datasheet shows an RTCCIE bit in the PIE3 register and a corresponding interrupt flag but curiously these bits aren't mentioned anywhere else in the datasheet.
The alarm section does have this very cryptic reference on interrupts.
17.3.2 ALARM INTERRUPT
At every alarm event, an interrupt is generated. Additionally,
an alarm pulse output is provided that operates
at half the frequency of the alarm.
The alarm pulse output is completely synchronous with
the RTCC clock and can be used as a trigger clock to
other peripherals. This output is available on the RTCC
pin. The output pulse is a clock with a 50% duty cycle
and a frequency half that of the alarm event (see
Figure 17-6).
The RTCC pin can also output the seconds clock. The
user can select between the alarm pulse, generated by
the RTCC module, or the seconds clock output.
The RTSECSEL (PADCFG1<2:1>) bits select between
these two outputs:
• Alarm pulse – RTSECSEL<2:1> = 00
• Seconds clock – RTSECSEL<2:1> = 01
Would this be the interrupt for RTCCIE and RTCCIF bits??
And what does the rest of it mean?
Additionally, an alarm pulse output is provided that operates at half the frequency of the alarm.
What does that mean? How can an alarm have a frequency?
The documentation for the RTCC really is pretty dismal.
What I really need is an interrupt when the time changes. But I also what an interrupt when the alarm is triggered.
The alarm section does have this very cryptic reference on interrupts.
17.3.2 ALARM INTERRUPT
At every alarm event, an interrupt is generated. Additionally,
an alarm pulse output is provided that operates
at half the frequency of the alarm.
The alarm pulse output is completely synchronous with
the RTCC clock and can be used as a trigger clock to
other peripherals. This output is available on the RTCC
pin. The output pulse is a clock with a 50% duty cycle
and a frequency half that of the alarm event (see
Figure 17-6).
The RTCC pin can also output the seconds clock. The
user can select between the alarm pulse, generated by
the RTCC module, or the seconds clock output.
The RTSECSEL (PADCFG1<2:1>) bits select between
these two outputs:
• Alarm pulse – RTSECSEL<2:1> = 00
• Seconds clock – RTSECSEL<2:1> = 01
Would this be the interrupt for RTCCIE and RTCCIF bits??
And what does the rest of it mean?
Additionally, an alarm pulse output is provided that operates at half the frequency of the alarm.
What does that mean? How can an alarm have a frequency?
The documentation for the RTCC really is pretty dismal.
What I really need is an interrupt when the time changes. But I also what an interrupt when the alarm is triggered.