PIC18F47J53 Datasheet, PDF (253/586 Pages) Microchip Technology – 28/44-Pin, High-Performance USB Microcontrollers with nanoWatt XLP Technology

PIC18F47J53 FAMILY
17.3 Alarm
The alarm features and characteristics are:
• Configurable from half a second to one year
• Enabled using the ALRMEN bit (ALRMCFG<7>,
Register 17-4)
• Offers one-time and repeat alarm options
17.3.1 CONFIGURING THE ALARM
The alarm feature is enabled using the ALRMEN bit.
This bit is cleared when an alarm is issued. The bit will
not be cleared if the CHIME bit = 1 or if ALRMRPT  0.
The interval selection of the alarm is configured
through the ALRMCFG bits (AMASK<3:0>). (See
Figure 17-5.) These bits determine which and how
many digits of the alarm must match the clock value for
the alarm to occur.
The alarm can also be configured to repeat based on a
preconfigured interval. The number of times this
occurs, after the alarm is enabled, is stored in the
ALRMRPT register.
Note:
While the alarm is enabled (ALRMEN = 1),
changing any of the registers, other than
the RTCCAL, ALRMCFG and ALRMRPT
registers, and the CHIME bit, can result in
a false alarm event leading to a false
alarm interrupt. To avoid this, only change
the timer and alarm values while the alarm
is disabled (ALRMEN = 0). It is recom-
mended that the ALRMCFG and
ALRMRPT registers and CHIME bit be
changed when RTCSYNC = 0.
FIGURE 17-5:
ALARM MASK SETTINGS
Alarm Mask Setting
AMASK<3:0>
0000 – Every half second
0001 – Every second
Day of the
Week Month
0010 – Every 10 seconds
0011 – Every minute
0100 – Every 10 minutes
0101 – Every hour
0110 – Every day
0111 – Every week
d
1000 – Every month
1001 – Every year⁽¹⁾
mm
Day
dd
dd
Hours Minutes Seconds
s
ss
m ss
mm s s
h h mm s s
h h mm s s
h h mm s s
h h mm s s
Note 1: Annually, except when configured for February 29.
 2010 Microchip Technology Inc.
Preliminary
DS39964B-page 253