Datasheet

 2009-2011 Microchip Technology Inc. DS39960D-page 237
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.
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).
FIGURE 18-2: TIMER DIGIT FORMAT
FIGURE 18-3: ALARM DIGIT FORMAT
0-60-9 0-9 0-3 0-9
0-9 0-9 0-90-2 0-5 0-5
0/1
Day of WeekYear Day
Hours
(24-hour format)
Minutes Seconds
1/2 Second Bit
0-1 0-9
Month
(binary format)
0-60-3 0-9
0-9 0-9 0-90-2 0-5 0-5
Day of WeekDay
Hours
(24-hour format)
Minutes Seconds
0-1 0-9
Month