Real-Time Clock (Rtca); Overview; Output Pin And External Connection; Output Pin - Epson S1C31D50 Technical Manual

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 calen-
dar (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.
RTCA
Clock generator
f
OSC1
OSC1
1/128
oscillator
RTCTRM[6:0]
RTCTRMBSY
RTCHLD
RTCRST
RTCRUN
RTCBSY
SWRST
SWRUN
SW1IE
SW10IE
SW100IE
ALARMIE
T1DAYIE
T1HURIE
T1MINIE
T1SECIE
T1_2SECIE
T1_4SECIE
T1_8SECIE
T1_32SECIE
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/D51 TECHNICAL MANUAL
(Rev. 2.00)
RTC RTC RTC RTC
128HZ 64HZ 32HZ 16HZ
RTC
count
control 128 64 32
Hz Hz Hz
circuit
1 Hz counter
BCD BCD
100[3:0] 10[3:0]
Stopwatch
count
control
1/100 1/10
circuit
s s
Stopwatch counter
SW1IF
SW10IF
SW100IF
ALARMIF
T1DAYIF
T1HURIF
T1MINIF
T1SECIF
Interrupt
T1_2SECIF
control
T1_4SECIF
circuit
T1_8SECIF
T1_32SECIF
Stopwatch counter interrupt
1 Hz 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) 1-second signal monitor output pin
* Indicates the status when the pin is configured for RTCA.
Seiko Epson Corporation
10 REAL-TIME CLOCK (RTCA)
RTC RTC RTC RTC
8HZ 4HZ 2HZ 1HZ
16 8 4 2 1
Hz Hz Hz Hz Hz
1-second
signal
RTC24H
RTCADJ
RTCAPA
RTCHHA[1:0]
/RTCHLA[3:0]
Comparator
RTCMIHA[2:0]
/RTCMILA[3:0]
RTCSHA[2:0]
/RTCSLA[3:0]
Function
RTC1S
Real-time
clock
counter
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