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8 Real-TiMe ClOCK (RTC)
S1C17153 TeChniCal Manual
Seiko epson Corporation
8-9
(Rev. 1.0)
• Counter values to be set must be within the effective range according to binary/BCD mode.
The counter will be undefined if a value out of the range is written.
• Depending on the value set, an interrupt may occur immediately after starting the RTC.
RTC hour Counter Register (RTC_h)
Register name address
Bit
name
Function
Setting
init. R/W
Remarks
RTC
hour Counter
Register
(RTC_h)
0x56c8
(16 bits)
D15–8
–
reserved
–
–
–
0 when being read.
D7
aMPM
AM/PM
1 PM
0 AM
X
R/W
D6
–
reserved
–
–
–
0 when being read.
D5–0
RTChOuR
[5:0]
Hour counter
0x0 to 0x17 (binary mode)
0x00 to 0x23 (BCD mode)
X
R/W
D[15:8] Reserved
D7
aMPM: aM/PM Bit
Indicates A.M. or P.M. when 12-hour mode is selected. (Default: undefined)
1 (R/W): P.M.
0 (R/W): A.M.
This bit is only effective when RTC24H/RTC_CTL register is set to 1 (12-hour mode).
When 24-hour mode is selected, this bit is fixed to 0. In this case, do not write 1 to AMPM.
note
: The AMPM bit will be fixed at 0 immediately after RTC24H/RTC_CTL register is changed from
12-hour mode to 24-hour mode.
D6
Reserved
D[5:0]
RTChOuR[5:0]: hour Counter Bits
These bits are used to read and write data from/to the hour counter. (Default: undefined)
The effective range of the read/setting values in binary mode (BCDMD = 0) are as follows:
• RTCHOUR[5:0] = 0x0 to 0x17 (0 to 23 o’clock) in 24-hour mode
• RTCHOUR[5:0] = 0x1 to 0xc (1 to 12 o’clock) in 12-hour mode
The effective range of the read/setting values in BCD mode (BCDMD = 1) are as follows:
• RTCHOUR[5:4] = 0x0 to 0x2 (10-hour digit) and RTCHOUR[3:0] = 0x0 to 0x9 (1-hour digit) in 24-
hour mode
• RTCHOUR[5:4] = 0x0 to 0x1 (10-hour digit) and RTCHOUR[3:0] = 0x0 to 0x9 (1-hour digit) in 12-
hour mode
notes
: • For the counter read and write procedures, see Section 8.3.5, “Counter Read,” and Section
8.3.4, “Counter Settings.”
• Do not set the counters while the RTC is running, as proper settings to the counters cannot be
guaranteed.
• Counter values to be set must be within the effective range according to binary/BCD mode.
The counter will be undefined if a value out of the range is written.
• Depending on the value set, an interrupt may occur immediately after starting the RTC.