Datasheet

2011-2012 Microchip Technology Inc. Preliminary DS61168E-page 191
PIC32MX1XX/2XX
20.0 REAL-TIME CLOCK AND
CALENDAR (RTCC)
The PIC32 RTCC module is intended for applications in
which accurate time must be maintained for extended
periods of time with minimal or no CPU intervention.
Low-power optimization provides extended battery
lifetime while keeping track of time.
Following are some of the key features of this module:
Time: hours, minutes and seconds
24-hour format (military time)
Visibility of one-half second period
Provides calendar: Weekday, date, month and
year
Alarm intervals are configurable for half of a
second, one second, 10 seconds, one minute, 10
minutes, one hour, one day, one week, one month
and one year
Alarm repeat with decrementing counter
Alarm with indefinite repeat: Chime
Year range: 2000 to 2099
Leap year correction
BCD format for smaller firmware overhead
Optimized for long-term battery operation
Fractional second synchronization
User calibration of the clock crystal frequency with
auto-adjust
Calibration range: 0.66 seconds error per month
Calibrates up to 260 ppm of crystal error
Requirements: External 32.768 kHz clock crystal
Alarm pulse or seconds clock output on
RTCC pin
FIGURE 20-1: RTCC BLOCK DIAGRAM
Note 1: This data sheet summarizes the features
of the PIC32MX1XX/2XX family of
devices. It is not intended to be a
comprehensive reference source. To
complement the information in this data
sheet, refer to Section 29. “Real-Time
Clock and Calendar (RTCC)”
(DS61125) in the “PIC32 Family
Reference Manual”, which is available
from the Microchip web site
(www.microchip.com/PIC32).
2: Some registers and associated bits
described in this section may not be
available on all devices. Refer to
Section 4.0 “Memory Organization” in
this data sheet for device-specific register
and bit information.
RTCC Prescalers
RTCC Timer
Comparator
Compare Registers
Repeat Counter
ALRMTIME
HR, MIN, SEC
ALRMDATE
with Masks
RTCC Interrupt Logic
Alarm
Event
32.768 kHz Input
from Secondary
0.5s
Alarm Pulse
Set RTCC Flag
RTCVAL
ALRMVAL
RTCC
RTCOE
Oscillator (S
OSC)
CAL<9:0>
MONTH, DAY, WDAY
RTCTIME
HR, MIN, SEC
RTCDATE
YEAR, MONTH, DAY, WDAY
Seconds Pulse
RTSECSEL
0
1