PIC18F87K90 Datasheet, PDF (227/566 Pages) Microchip Technology – 64/80-Pin, High-Performance Microcontrollers with LCD Driver and nanoWatt XLP Technology

PIC18F87K90 FAMILY
17.1.4 RTCEN BIT WRITE
RTCWREN (RTCCFG<5>) must be set before a write
to RTCEN can take place. Any write to the RTCEN bit,
while RTCWREN = 0, will be ignored.
Like the RTCEN bit, the RTCVALH and RTCVALL
registers can only be written to when RTCWREN = 1.
A write to these registers, while RTCWREN = 0, will be
ignored.
FIGURE 17-2:
TIMER DIGIT FORMAT
Year
Month
0-9
0-9
0-1
0-9
Hours
(24-hour format)
0-2
0-9
Minutes
0-5
0-9
17.2 Operation
17.2.1 REGISTER INTERFACE
The register interface for the RTCC and alarm values is
implemented using the Binary Coded Decimal (BCD)
format. This simplifies the firmware when using the
module as each of the digits is contained within its own
4-bit value (see Figure 17-2 and Figure 17-3).
Day
0-3
0-9
Seconds
0-5
0-9
Day Of Week
0-6
1/2 Second Bit
(binary format)
0/1
FIGURE 17-3:
ALARM DIGIT FORMAT
Month
Hours
(24-hour format)
0-2
0-9
0-1
0-9
Minutes
0-5
0-9
Day
0-3
0-9
Seconds
0-5
0-9
Day Of Week
0-6
 2010 Microchip Technology Inc.
Preliminary
DS39957B-page 227