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10. Real-Time Clock (RTCA)
10.1. Overview
RTCA is a real-time clock with a perpetual calendar function. The main features of RTCA are outlined
below.
•
Includes a BCD real-time clock counter to implement a time-of-day clock (second, minute, and hour)
and calendar (day, day of the week, month, and year with leap year supported).
•
Provides a hold function for reading correct counter values by suspending the real-time clock counter
operation.
•
24-hour or 12-hour mode is selectable.
•
Capable of controlling the starting and stopping of the time-of-day clock.
•
Provides a 30-second correction function to adjust time using a time signal.
•
Includes a 1 Hz counter to count 128 to 1 Hz.
•
Includes a BCD stopwatch counter with 1/100-second counting supported.
•
Provides a theoretical regulation function to correct clock error due to frequency tolerance with no
external parts required.
Figure 10.1.1 shows the configuration of RTCA.
Clock generator
RTCA
OSC1
1/128
oscillat
RTCTRM[6:0]
or
CPU core
10.2. Output Pin and External Connection
10.2.1. Output Pin
Table 10.2.1.1 shows the RTCA pin.
Pin name
I/O*
RTC1S
O
If the port is shared with the RTCA output function and other functions, the RTCA function must be
assigned to the port. For more information, refer to the "I/O Ports" chapter.
S1C31D50 TECHNICAL MANUAL
(Rev. 1.00)
RTC
RTC
128HZ
64HZ
RTC
RTCTRMBSY
count
RTCHLD
control
128
64
RTCRST
Hz
Hz
t
circui
RTCRUN
RTCBSY
BCD
Stopwatch
100[3:0]
10[3:0]
count
SWRST
control
1/100
SWRUN
circuit
s
Stopwatch counter
SW1IE
SW1IF
SW10IE
SW10IF
SW100IE
SW100IF
ALARMIE
ALARMIF
T1DAYIE
T1DAYIF
T1HURIE
T1HURIF
T1MINIE
T1MINIF
T1SECIE
T1SECIF
Interrupt
T1_2SECIE
T1_2SECIF
control
T1_4SECIE
T1_4SECIF
circuit
T1_8SECIE
T1_8SECIF
T1_32SECIE
T1_32SECIF
Stopwatch counter interrupt
1Hz counter interrupt
Alarm interrupt
Real-time clock counter interrupt
Figure 10.1.1 RTCA Configuration
Table 10.2.1.1 RTCA Pin
Initial status*
O (L)
Seiko Epson Corporation
RTC
RTC
RTC
RTC
RTC
RTC
32HZ
16HZ
8HZ
4HZ
2HZ
1HZ
32
16
8
4
2
1
Hz
Hz
Hz
Hz
Hz
Hz
1-second
1 Hz counter
signal
BCD
RTC24H
RTC24H
1/10
RTCAPA
s
RTCHHA[1:0]
/RTCHLA[3:0]
Comparator
RTCMIHA[2:0]
/RTCMILA[3:0
]
RTCSHA[2:0]
/RTCSLA[3:0]
Function
1-second signal monitor output pin
* Indicates the status when the pin is configured for RTCA.
RTC1S
Day of
RTCWK[2:0]
week
RTCYH[3:0]
Year
/RTCYL[3:0]
RTCMOH
Month
/RTCMOL[3:
0]
RTCDH[1:0]
Day
/RTCDL[3:0]
A.M./
RTCAP
P.M.
RTCHH[1:0]
Hour
/RTCHL[3:0]
RTCMIH[2:0]
Minute
/RTCMIL[3:0
]
RTCSH[2:0]
Second
/RTCSL[3:0]
10-1
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