PIC18F87K22 Datasheet, PDF (235/548 Pages) Microchip Technology – 64/80-Pin, High-Performance, 1-Mbit Enhanced Flash Microcontrollers with 12-Bit A/D and nanoWatt XLP Technology

PIC18F87K22 FAMILY
18.1.4 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 18-2:
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
18.2 Operation
18.2.1 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 18-2 and Figure 18-3).
Day
0-3
0-9
Seconds
0-5
0-9
Day Of Week
0-6
1/2 Second Bit
(binary format)
0/1
FIGURE 18-3:
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
DS39960B-page 235