Datasheet

 2009 Microchip Technology Inc. DS39897C-page 251
PIC24FJ256GB110 FAMILY
20.0 REAL-TIME CLOCK AND
CALENDAR (RTCC)
The Real-Time Clock and Calendar (RTCC) provides
on-chip, hardware-based clock and calendar function-
ality with little or no CPU overhead. It is intended for
applications where accurate time must be maintained
for extended periods with minimal CPU activity and
with limited power resources, such as battery-powered
applications.
Key features include:
• Time data in hours, minutes and seconds, with a
granularity of one-half second
• 24-hour format (Military Time) display option
• Calendar data as date, month and year
• Automatic, hardware-based day of the week and
leap year calculations for dates from 2000
through 2099
• Time and calendar data in BCD format for
_compact firmware
• Highly configurable alarm function
• External output pin with selectable alarm signal or
seconds “tick” signal output
• User calibration feature with auto-adjust
A simplified block diagram of the module is shown in
Figure 20-1. The SOSC and RTCC will both remain
running while the device is held in Reset with MCLR
and will continue running after MCLR is released.
FIGURE 20-1: RTCC BLOCK DIAGRAM
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, refer to the
“PIC24F Family Reference Manual”,
Section 29. “Real-Time Clock and
Calendar (RTCC)” (DS39696).
RTCC Prescalers
RTCC Timer
Comparator
Compare Registers
Repeat Counter
YEAR
MTHDY
WKDYHR
MINSEC
ALMTHDY
ALWDHR
ALMINSEC
with Masks
RTCC Interrupt Logic
RCFGCAL
ALCFGRPT
Alarm
Event
32.768 kHz Input
from SOSC Oscillator
0.5s
RTCC Clock Domain
Alarm Pulse
RTCC Interrupt
CPU Clock Domain
RTCVAL
ALRMVAL
RTCC Pin
RTCOE