Datasheet

Real Time Clock (RTC)
Technical Data MC68HC908LJ12 — Rev. 2.1
210 Real Time Clock (RTC) Freescale Semiconductor
12.2 Introduction
This section describes the real time clock (RTC) module. The RTC
provides real time clock and calendar functions with automatic leap year
adjustments. Other functions include alarm interrupt, periodic interrupts,
and a chronograph timer.
12.3 Features
Features of the RTC module include:
• Counter registers for:
– Second
– Minute
–Hour
–Day
– Day-of-week
–Month
–Year
• Day counter with automatic month and leap year adjustment
• 1/100 seconds chronograph counter
• Seven periodic interrupts
• Alarm interrupt
Addr.Register Name Bit 7654321Bit 0
$0042
RTC Control Register 1
(RTCCR1)
Read:
ALMIE CHRIE DAYIE HRIE MINIE SECIE TB1IE TB2IE
Write:
Reset:00000000
$0043
RTC Control Register 2
(RTCCR2)
Read: 0
0
CHRE RTCE
0
XTL2 XTL1 XTL0
Write: R CHRCLR
Reset:00000000
= Unimplemented R = Reserved
Figure 12-1. RTC I/O Register Summary