PIC24FV32KA304 Datasheet, PDF (189/322 Pages) Microchip Technology – 20/28/44/48-Pin, General Purpose, 16-Bit Flash Microcontrollers with XLP Technology

PIC24FV32KA304 FAMILY
19.0 REAL-TIME CLOCK AND
CALENDAR (RTCC)
Note:
This data sheet summarizes the features of
this group of PIC24F devices. It is not
intended to be a comprehensive reference
source. For more information on the
Real-Time Clock and Calendar, refer to the
“PIC24F Family Reference Manual”,
Section 29. “Real-Time Clock and
Calendar (RTCC)” (DS39696).
The RTCC provides the user with a Real-Time Clock
and Calendar (RTCC) function that can be calibrated.
Key features of the RTCC module are:
• Operates in Deep Sleep mode
• Selectable clock source
• Provides hours, minutes and seconds using
24-hour format
• Visibility of one half second period
• Provides calendar – weekday, date, month and
year
• Alarm-configurable for half a second, one second,
10 seconds, one minute, 10 minutes, one hour,
one day, one week, one month or one year
• Alarm repeat with decrementing counter
• Alarm with indefinite repeat chime
• Year 2000 to 2099 leap year correction
FIGURE 19-1:
RTCC BLOCK DIAGRAM
• BCD format for smaller software overhead
• Optimized for long term battery operation
• User calibration of the 32.768 kHz clock
crystal/32K INTRC frequency with periodic
auto-adjust
• Optimized for long term battery operation
• Fractional second synchronization
• Calibration to within ±2.64 seconds error per
month
• Calibrates up to 260 ppm of crystal error
• Ability to periodically wake up external devices
without CPU intervention (external power control)
• Power control output for external circuit control
• Calibration takes effect every 15 seconds
• Runs from any one of the following:
- External real-time clock of 32.768 kHz
- Internal 31.25 kHz LPRC clock
- 50 Hz or 60 Hz External input
19.1 RTCC Source Clock
The user can select between the SOSC crystal
oscillator, LPRC internal oscillator or an external
50 Hz/60 Hz power line input as the clock reference for
the RTCC module. This gives the user an option to
trade off system cost, accuracy and power
consumption, based on the overall system needs.
Input from
SOSC/LPRC
Oscillator or
external source
Alarm
Event
RTCC Clock Domain
RTCC Prescalers
0.5 Sec
RTCC Timer
Comparator
CPU Clock Domain
RCFGCAL
ALCFGRPT
RTCVAL
YEAR
MTHDY
WKDYHR
MINSEC
Alarm Registers with Masks
ALRMVAL
ALMTHDY
ALWDHR
ALMINSEC
Repeat Counter
RTCC Interrupt Logic
RTSECSEL<1:0>
RTCC
Interrupt
Alarm Pulse
1s
01
00
Clock Source
RTCOE
10
RTCC
Pin
 2011 Microchip Technology Inc.
DS39995A-page 189