
8.0 Real-Time Clock (RTC)
(Continued)
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8.3.2
The RTC runtime registers can be accessed at any time during normal or standby operation; i.e., when V
SB
and/or V
DD
are
within the recommended operation range. The access is disabled during battery-backed operation. Write operation to these
registers is also disabled if bit 7 of the CRD register is 0 (see Section 8.3.16 on page 157).
Note: Before attempting to perform any start-up procedures, read the explanation of bit 7 (VRT) of the CRD register (see
Section 8.3.16 on page 157).
See Section 8.6 on page 160 for a detailed description of the memory map for the RTC registers.
This section describes the RTC Timing and Control registers that control basic RTC functionality. All registers are V
PP
pow-
ered.
RTC Runtime Register Map
8.3.3
Power Well:V
PP
Location: Index 00h
Type:
R/W
Seconds Register (SEC)
Index
Mnemonic
Name
Type
Power
Well
Reset
Section
00h
SEC
Seconds Register
R/W
V
PP
V
PP
PUR
8.3.3
01h
SECA
Seconds Alarm Register
R/W
V
PP
V
PP
PUR
8.3.4
02h
MIN
Minutes Register
R/W
V
PP
V
PP
PUR
8.3.5
03h
MINA
Minutes Alarm Register
R/W
V
PP
V
PP
PUR
8.3.6
04h
HOR
Hours Register
R/W
V
PP
V
PP
PUR
8.3.7
05h
HORA
Hours Alarm Register
R/W
V
PP
V
PP
PUR
8.3.8
06h
DOW
Day-of-Week Register
R/W
V
PP
V
PP
PUR
8.3.9
07h
DOM
Date-of-Month Register
R/W
V
PP
V
PP
PUR
8.3.10
08h
MON
Month Register
R/W
V
PP
V
PP
PUR
8.3.11
09h
YER
Year Register
R/W
V
PP
V
PP
PUR
8.3.12
0Ah
CRA
RTC Control Register A
Varies per bit
V
PP
Bit specific
8.3.13
0Bh
CRB
RTC Control Register B
R/W
V
PP
Bit specific
8.3.14
0Ch
CRC
RTC Control Register C
R/O
V
PP
Bit specific
8.3.15
0Dh
CRD
RTC Control Register D
R/O
V
PP
V
PP
PUR
8.3.16
Programmable
1
by DOMAO
1. Overlaid on RAM bytes in range 0Eh-7Fh.
DOMA
Date-of-Month Alarm Register
R/W
V
PP
V
PP
PUR
8.3.17
Programmable
1
by MONAOMONA
Month Alarm Register
R/W
V
PP
V
PP
PUR
8.3.18
Programmable
1
by CENO
CEN
Century Register
R/W
V
PP
V
PP
PUR
8.3.19
Bit
7
6
5
4
3
2
1
0
Name
Seconds Data
Reset
0
0
0
0
0
0
0
0
Bit
Description
7-0
Seconds Data.
Values may be 00 to 59 in BCD format or 00 to 3B in Binary format.