RX8111CE
Page
−
15
ETM61E-01
13.
Overview of Functions and Description Of Registers
Note. The initialization of registers is necessary about the unused function too.
13.1. Overview Of Functions
1) Clock Function
This function is used to set and read out second, minute, hour, day, month, year ( to the last two digits), and date data.
Any (two-digit) year that is a multiple of 4 is treated as a leap year and calculated automatically as such until the year 2099. Also
“60” sec writing is available for leap second.
At the start of a I
2
C communication, the time and clock counting stops (which causes loss of time), and clock starts automatically
again at the end of the I
2
C communication.
2) Wake-up Timer Interrupt Function
The wake-up timer interrupt function generates an interrupt event periodically at any fixed cycle set between 244.14
s
and 32
years. When an interrupt event is generated, the /INT pin goes to low level (Low) and "1" is set to the TF bit to report that an event
has occurred.
The timer data can be read even timer is running. The timer operates in both timer pause and running, so this function realizes a
cumulative timer, wake-up timer etc.
3) Alarm Interrupt Function
The alarm interrupt function generates interrupt events for alarm settings such as date, day, hour, and minute settings. When an
interrupt event occurs, the AF bit value is set to "1"
and the /INT pin goes to low level to indicate that an event has occurred.
4) Lower Operation Voltage Detection Function (VLF)
Lower voltage of V
OUT
terminal can be detected
During power on initialization or recovery of backup this function judges the clock data reliability.
If lower voltage is detected power on reset function moves this RTC device to initial condition.
5) Lower Battery Backup Voltage Detection Function (VLOW)
Lower voltage of V
BAT
terminal can be detected
6) Crystal Oscillation Stop Detection Function (XST)
RTC inner crystal oscillation stop can be detected.
7) Clock Output Function (FOUT)
Either 32.768
kHz,1024 Hz or 1 Hz clock is available at FOUT terminal.
Wake-up timer interrupt function available if FOUT function is not used.
8) Time Stamp Function
The function can be used, for example, to record the time of system software updates, battery replacements, and system alerts.
Time-stamps are stored even when power is switched over to the alternative battery source, contributing to system robustness.
8 times stamped from year to 1/256 seconds.
The time stamp trigger inputs from EVIN pin, self-monitoring and I
2
C software command.
9) User RAM
Built-in 8bit
64word (512bit) RAM for general purpose memory or Time Stamp memory.
It selectable for user
’s RAM or Time Stamp memory.
