RX8804CE
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ETM59E-05
3) VDET (Voltage Detection Flag) bit
This flag bit indicates the history of the voltage for temperature compensation circuit.
Its value changes from “0” to “1” indicates that the temperature compensation function has stopped operation due
to a supply voltage drop. Once this flag bit's value is 1, its value is retained until a 0 is written to it.
After poweri
ng up from 0 V, make sure to set this bit's value to “1”. Please confirm table in 8.11. Backup and
Recovery.
Table 21 VDET bit
VDET
Data
Description
Write
0
The VDET bit is cleared to 0 to prepare for the next low voltage detection
1
VDET data remains even it was 0 or 1. To retain the data, please write 1
Read
0
Temperature compensation is normal
1
Temperature compensation has been stopped
4) RESET bit
When highly precise synchronization of both time, timer is necessary, use RESET.
Table 22 RESET bit
RESET
Data
Description
Write
0
Writing 0 is invalid
1
Writing 1 resets 16384 Hz ~2 Hz of 32.768 kHz counter (Refer to Figure 6)
Read
0
The read value of RESET is 0, always
writes 0, it is invalid
1
writes 1, it executes reset of count-down-chain from 32.768kHz
The detailed function of RESET.
For example.
S is start condition. P is stop condition.
[ Write access to RESET-bit.]
S---Slave address(w)---ACK1---0Fh---ACK2---01h---ACK3---P.
RESET executes and it keeps between P from ACK3.
After P, RESET bit clears automatically.
reset area of circuit are the count-down-chain of 2 Hz from 16 kHz, are cleared.
As for next update timing of a Seconds counter from RESET.
That range is 1000 ms-30.5
s from just 1000 ms.
RESET affects time update interruption, alarm, FOUT and timer.
But it doesn't affect 32 kHz output.
Note:
RESET is released by the reception of a START or RE-START condition before receiving a STOP condition.
The Single write access is recommended for precise RESET.
Unnecessary use of RESET will be the cause of delay error of time.
5) USEL (Update Interrupt Select) bit
This bit is used to define if the RTC should output a
“second update” or “minute update” interrupt, allowing to
synchronize external clocks with the time registers of the RTC.
Please refer to 8.6. Time Update Interrupt Function
6) TSEL0, 1 (Timer Select 0, 1) bits
The combination of these two bits is used to set the countdown period (source clock) for the wakeup timer
interrupt function (four settings can be made).
Please refer to 8.3. Wakeup Timer Function