Datasheet

 2009-2011 Microchip Technology Inc. DS39960D-page 229
PIC18F87K22 FAMILY
18.1.1 RTCC CONTROL REGISTERS
REGISTER 18-1: RTCCFG: RTCC CONFIGURATION REGISTER
(1)
R/W-0 U-0 R/W-0 R-0 R-0 R/W-0 R/W-0 R/W-0
RTCEN
(2)
—RTCWREN
(4)
RTCSYNC HALFSEC
(3)
RTCOE RTCPTR1 RTCPTR0
bit 7 bit 0
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
bit 7 RTCEN: RTCC Enable bit
(
2
)
1 = RTCC module is enabled
0 = RTCC module is disabled
bit 6 Unimplemented: Read as ‘0’
bit 5 RTCWREN: RTCC Value Registers Write Enable bit
(4)
1 = RTCVALH and RTCVALL registers can be written to by the user
0 = RTCVALH and RTCVALL registers are locked out from being written to by the user
bit 4 RTCSYNC: RTCC Value Registers Read Synchronization bit
1 = RTCVALH, RTCVALL and ALRMRPT registers can change while reading if a rollover ripple
results in an invalid data read. If the register is read twice and results in the same data, the data
can be assumed to be valid.
0 = RTCVALH, RTCVALL and ALCFGRPT registers can be read without concern over a rollover
ripple
bit 3 HALFSEC: Half-Second Status bit
(3)
1 = Second half period of a second
0 = First half period of a second
bit 2 RTCOE: RTCC Output Enable bit
1 = RTCC clock output is enabled
0 = RTCC clock output is disabled
bit 1-0 RTCPTR<1:0>: RTCC Value Register Window Pointer bits
Points to the corresponding RTCC Value registers when reading the RTCVALH and RTCVALL
registers. The RTCPTR<1:0> value decrements on every read or write of RTCVALH<15:8> until it
reaches ‘00’.
RTCVALH:
00 = Minutes
01 = Weekday
10 = Month
11 = Reserved
RTCVALL:
00 = Seconds
01 = Hours
10 = Day
11 = Year
Note 1: The RTCCFG register is only affected by a POR.
2: A write to the RTCEN bit is only allowed when RTCWREN = 1.
3: This bit is read-only; it is cleared to ‘0’ on a write to the lower half of the MINSEC register.
4: RTCWREN can only be written with the unlock sequence (see Example 18-1).